1 
 

1.1. Introduction 

Natural products (NPs) have been used to combat human diseases for thousands of years; and 

therefore play a vital role in drug discovery and development (Thomford et al., 2018). Most of the 

NPs with therapeutic efficacy are secondary metabolites. The underlying reason for NPs as 

sources of such a large proportion of existing drugs might be the similar interaction of NPs with 

biosynthetic enzymes and therapeutic targets (Nair and Jez, 2020). NPs provide greater structural 

diversity than standard combinatorial chemistry and thus they offer major opportunity for finding 

novel therapeutic leads that are active against a wide range of assay targets. Moreover, they 

contain higher numbers of chiral centers and greater stearic complexity than either synthetic drugs 

or combinatorial libraries. Generally, biologically active NPs with drug like properties are small 

molecules that are capable of being absorbed and metabolized by the body. In addition, the 

development costs of NPs as medicines are likely to be much lower than that of biotechnological 

products or compounds produced from combinatorial chemistry (Wright, 2019). 

             Plants are the basis of traditional medicine (TM) systems that have been used for 

thousands of years. The plant based TM system continue to play important role in healthcare and 

according to the report of World Health Organization (WHO), about 80% of the world’s 

population rely mainly on TM for their primary health care. TM and ethnobotanical information 

have also played an important role in scientific research, particularly when the literature and field 

work data have been properly evaluated (Chaachouay et al., 2019). A large number of plant 

derived NPs continue to be discovered on the basis of traditional or empirical local medical 

practices. Globally, about 80% of plant derived drugs have the same or related use as the plants 

from which they were derived and rest only 20% of plant derived drugs were discovered 

independently of medicinal folklore information. According to a report only 10% of the world’s 

biodiversity has been tested for biological activity, still many more useful NPs are remains to be 

identified.  

            Plants are endowed with a variety of bioactive chemicals that may have a synergistic 

effect on plant biological activities. Thus, in order to identify safer drugs and synthesize 

pharmaceutically significant lead chemicals, it is essential to screen active substances and 

understand their chemical composition (Mariswamy et al., 2011). With the emergence of several 

purification techniques and the isolation of pure compounds or phytochemicals, drug discovery 

might be facilitated. These compounds have been discovered to play a potential role in many 

pathway regulations and could be used as ligands for in silico drug design. Severel 

chromatography techniques, like column chromatography, thin layer chromatography, high 

performance liquid chromatography, flash chromatography and Sephadex chromatography have 

been used to separate bioactive substances for identification, quantification and characterization 

(Sasidharan et al., 2011). Despite variations in the polarity of phytochemicals continue to pose a 

challenge for isolating pure compounds, several plant derived therapeutics NPs have been 

developed (Sheeja and Kuttan, 2007; Mukherjee et al., 2007). 



2 
 

          Recent trend of research based on bioactive plants to develop drugs for anticancer, antiviral, 

antiprotozoal, antidiabetic and cardiovascular diseases. The strategy for plant based NP drug 

discovery generally involves testing of plant extracts in appropriate in vitro assays 

(cytotoxicity/cytostatic or enzyme/target based), followed by bioassay-guided fractionation of the 

active extracts and isolation and purification of active constituents. Those constituents showing 

significant in vivo activity in appropriate animal models are considered as lead molecules which 

may be selected as candidates for preclinical development (Cragg et al., 2005). 

           Several disease conditions are associated with increased production of free radicals 

through oxidation reduction mechanisms leading to oxidative stress to cause cellular damages 

(Ratnam et al., 2006). To neutralize or balance the creation of free radicals, each individual is 

gifted with a sophisticated defense system that includes enzymes such as catalases, superoxide 

dismutase, glutathione peroxidase and glutathione reductase; or substances such as glutathione, 

vitamins E, C and others. Antioxidants are compounds that can counteract the negative effects of 

free radicals. Lowered levels of antioxidant on the other hand, result in the production of 

excessive free radicals, which can lead to a variety of diseases, including cancer, stroke, 

myocardial infarction, diabetes, septic and hemorrhagic shock, Alzheimer's and Parkinson's 

diseases (Tsao et al., 2004; Pavelescu, 2015). Synthetic antioxidants such as butylated hydroxyl 

anisole, butylated hydroxyl toluene and others play a significant role in delaying or avoiding 

oxidative stress-related disorders, but they have a number of negative health effects (Sultana et 

al., 2007). 

            Additionally, in current years, the incidence of deaths from infectious diseases has 

increased dramatically, as the reports on drug-resistant human pathogenic bacteria from 

throughout the world (Mahesh and Satish, 2008; Demiraslan and Uysal, 2016). Infectious disease 

management with plant-based antimicrobials has been proven to be successful in the past because 

unlike synthetic antimicrobials they generally lack the negative side effects. Furthermore, 

phytomedicines have a variety of effects in the body. Hydrastis canadensis, for example, not only 

has antimicrobial properties but also increases blood supply to the spleen, accelerating the 

discharge of mediators (Murray, 1995). 

Diabetes mellitus (DM) is a global health problem affecting quite a number of people from 

all walks of life. In our country the current disease burden estimate is 25 million. According to 

ICMR report (2002), it is projected that by 2025 there would be 57 million diabetics in India, 

mainly those having Type-II diabetes. There appears to be a host of potential genetic, 

environmental and immunological risk factors that may be involved in the etiology and 

pathogenesis of these aberrations. Moreover, Type-II DM has been observed as a new epidemic 

among pediatric population and as in the adult population, Type-II DM in children and youth 

occurs as a result of insulin resistance coupled with relative β-cell failure. DM is still not 

completely curable by the present anti-diabetic agents. Insulin therapy is the only satisfactory 

approach in DM, even though it has several drawbacks like insulin resistance (Chen et al., 2022), 

anorexia, brain atrophy and fatty liver in chronic treatment (Tsimihodimos et al., 2018). DM is 



3 
 

threatening because of the development of many severe secondary complications, including 

atherosclerosis, microangiopathy, renal dysfunction and failure, cardiac abnormalities, diabetic 

retinopathy and ocular disease (Shah et al., 2021). TM is a fruitful source of future drugs to 

counteract insulin resistance, consistent with a resurgence of interest in drug discovery from NPs. 

For example, metformin is a biguanide derivative of guanide, originated from the plant Goat’s 

Rue (Galega officinalis) as a structure-modified natural product to vastly improve its efficacy. A 

major advantage of TM is that they have been used to treat human diseases for many years and so 

there is considerable knowledge concerning in vivo efficacy and safety, two of the confounding 

problems facing other new chemical entities (Tan et al., 2008). 

India is one of the twelve mega-biodiversity countries of the World having rich vegetation 

with a wide variety of plants with medicinal value with northeastern region being the biodiversity 

hotspot (Patrick, 2002; Saha et al., 2011). The floristic wealth of north eastern region is nearly 

43% of the country’s total flora and good number of known and unknown medicinal plants are 

found in the forest of the Darjeeling district of West Bengal and the state of Sikkim, India 

(Mukherjee et al., 2007). The tribal people of this region possess a great knowledge on the uses of 

medicinal plants for the treatment of various kinds of diseases, which includes wounds, diarrhea, 

dysentery, diabetes, jaundice and skin infection etc (Hussain et al., 2008). Phytochemicals, such 

as phenolics, flavonoids and steroids have received a lot of attention in current years because of 

their antioxidative, antimutagenic, antidiabetic, antiallergenic, anti-inflammatory, antimicrobial, 

anticoagulant, antiproliferative, antitumor, antibacterial, antiviral and antiadhesive properties, as 

well as their potential to prevent neurodegenerative diseases, cardiovascular disorders and various 

forms of cancer (Kang et al., 2006; Yoo et al., 2018). 

Darjeeling Himalaya is situated between 87°53ʹ East longitude and 28°10ʹ North 

longitude in India. The region though very small in area, is rich in floral diversity and density, 

many endemic elements and a number of species which have become rare, threatened or 

endangered (Chhetri et al., 2005). The richness in medicinal plants is related to the richness in 

vegetation composition. The tribes of this Himalayan region (Nepalese, Lepchas and Bhutias) 

also have rich ethnomedicinal traditions for which a few literature are available (Bantawa and 

Rai, 2009). These literatures are the source for selecting the plants having various medicinal 

properties. Although, ethno-pharmacological studies have documented several of these plants 

with anti-diabetic activity, they have never been explored for developing antidiabetic agents. 

Plant pre-fractionated libraries can be an effective strategy to identify the active 

principle due to following reasons: (i) the samples produced by the pre-fractionation approach are 

simpler mixtures and the final resolution of active components requires fewer purification steps. 

(ii) Interferences are reduced due to the fact that extremely polar and extremely non-polar 

components are separated from the bulk of the library samples and (iii) the relative concentration 

of minor components is increased over that in the crude, thereby enhancing the opportunity to 

uncover novel biologically active metabolites. Hence, the present investigation aimed at selection 

of plants with anti-diabetic potential on the basis of ethno-pharmacological studies and analyzing 



4 
 

the plant/plant parts for phytochemicals, antimicrobial and antioxidant activities; and pre-

fractionation of natural compounds from plant sample with potent antimicrobial and antioxidant 

activities, and further screening of  the fractions for anti-diabetic potential by in vitro assay, and 

finally, in vivo activity of the active component in rat model system.  

 

 

 

 

 

1.2. Objectives 

1. Collection and identification of some ethnomedicinally important plants of Darjeeling 

Himalayan region. 

2. Qualitative and quantitative phytochemical screening of the plant samples. 

3. Determination of the antioxidant activities of plant samples. 

      4.   Isolation and characterization of active compound(s) from plant samples having potent   

antimicrobial and antioxidant activities. 

      5.   Performing in-vitro antidiabetic activities of active compound(s) from the selected plant    

samples.  

      6.   To study the in-vivo antidiabetic activities of active compound(s) in the rat model system. 

 

 

 

 

 

 

 

 

 

 



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1.3. Review of literature  

Plants have served as the primary source of energy (O2, food, fabric and medications) for all kinds 

of life. Most crucially, plants are being studied as therapeutic agents since the dawn of 

civilization, some 60,000 years ago (Prasathkumar et al., 2021). The great civilizations of the 

ancient Chinese, Indians and North Africans have provided documentary evidence of the same. 

The earliest account of the use of plants as medicine in India can be found in the Rig Veda, which 

dates from 3500 B.C. to 1800 B.C. Plants have always played an important part in primary health 

care, dating back to ancient times. Theophrastus, commonly regarded as the "Father of Botany," 

was a constant source of information that aided in plant identification. However, man did not 

become aware of the active elements of plants until the nineteenth century. The French scientists 

Caventou and Pelletier discovered quinine from Cinchona bark; morphine and codeine extraction 

from poppy; digoxin derived from Digitalis leaves; reserpine from Rauwolfia species; vinblastine 

and vincristine from Catharanthus roseus and so on. In addition, pharmacological research 

brought to the production of the first synthetic medication, ‘aspirin’, which was based on the 

natural chemical ‘salicylic acid’ (Sneader, 2000). For a long time, the value of natural 

phytochemicals declined as synthetic drug development took hold. Although, in recent decades, 

the search for natural medications has accelerated, as synthetic drugs have been linked to a slew 

of side effects. Taxol, etoposide and artemisinin were among the natural medications identified 

(Phillipson, 1999), piqueing interest in the usage of natural remedies as secure substitutes. 

Furthermore, the inclusion of many chemical compounds may have a synergistic or cumulative 

pharmacological impact, eliminating negative side effects associated with the usage of single 

xenobiotics (Tyler, 1999). NPs from plants have been the basis of traditional medicine system and 

it has been estimated by World Health Organization (WHO) that in both advanced and developing 

nations, 80–85% of the population depends on traditional medicine for their fundamental 

healthcare requirement and the major part of traditional therapy involves the use of plant extracts 

or their active principles (Elujoba et al., 2005; Ignacimuthu et al., 2006; Alves and Rosa, 2007).  

            Nature has provided us with all of the necessary components to maintain life on this Earth 

since the beginning of time. It has also proven to be an effective source of severel therapeutic 

herbs, from which a significant number of modern medications have been identified and 

successfully used to cure a variety of disorders. Chemical substances that provide health-

promoting action on the human body have been known to confer therapeutic benefits. Despite the 

fact that ethnobotanical plants have been employed in conventional medicine since antiquity, they 

have been largely overlooked in modern times. However, numerous studies have been published 

on the effectiveness of certain ethnic plants as antiviral, antirheumatic, anticancer, antidiabetic, 

antiinflammation and antibacterial medicines. In this context, a brief assessment of the following 

topics linked to the current investigation has been assembled and presented: phytochemical 

screening of ethnobotanical plants, their role as antioxidative, antimicrobial and antidiabetic 

agents (Kumar et al., 2021). 



6 
 

1.3.1. Phytochemical screening of plants 

Plants contain bioactive, naturally produced substances known as phytochemicals that have been 

shown to produce particular physiological effects on humans (Saxena et al., 2013). They help to 

protect plants from biotic and abiotic stressors, as well as contribute to their colour, scent and 

flavour. Individuals and societies have long been aware that phytochemicals play a vital role in 

their health. Several phytochemicals are recognized or identified; there is still some obscurity in 

their classification. Moreover, they have been categorized into primary and secondary 

metabolites. The primary metabolites include amino acids, proteins, sugars, nucleic acids, purines 

and pyrimidines, chlorophyll and others. The secondary metabolites include phenolics, alkaloids, 

terpenes, flavonoids, lignans, plant steroids, saponins and glucosides (Agidew, 2022). Phenolics 

are the most frequent and structurally variable plant phytoconstituents among the different 

secondary metabolites. The occurence of diverse bioactive substances in medicinal plants, as well 

as their importance to the welfare of individuals and communities, has piqued the interest of 

researchers all over the globe to investigate the plants' biological activities. Alkaloids, tannins, 

flavonoids and phenolic chemicals are the most essential bioactive elements of plants (Kang, 

2014). A study was conducted by Edeoga et al., (2005) to evaluate, analyze and estimate the 

percentage of crude phytochemical present in ten different medicinal plants, namely Tridxa 

procumbens, Cleome rutidosperma, Euphrobia heterophylla, Emilia coccinea, Physcalis 

bransilensis, Richardia bransilensis, Scorparia dulcis, Sida acuta, Stachytarpheta cayennensis, 

Spigelia anthelmia and widely utilized as natural remedy in South Eastern Nigeria. They found 

alkaloid and flavonoid in all of the samples, however tannin was only not found in Sida acuta. 

With the exception of Tridxa procumbens, all of the samples contained cardiac glycoside. 

Saponin was not found in Euphrobia heterophylla or Sida acuta, but it was found in all other 

samples. Only Emilia coccinea, Physcalis bransilensis, Richardia bransilensis and Spigelia 

anthelmia contained steriod. Phlobatannin was only found in the following plants: Euphrobia 

heterophylla, Physcalis bransilensis, Scorparia dulcis, Spigelia anthelmia and Stachytarpheta 

cayennensis. Terpenoid was not found in Cleome rutidosperma, Scorparia dulcis, Spigelia 

anthelmia, Stachytarpheta cayennensis or Tridxa procumbens, but was found in the other species. 

The quantitative estimation of these phytochemicals showed that Sida acuta had the greatest 

percentage crude output of alkaloids (1.04%) and flavonoid (0.98%). Cleome rutido sperma had 

the lowest alkaloid output (0.32%) but the highest tannin content (15.25%). Saponin (3.92%) was 

discovered to be highest in Physcalis bransilensis, while phenols were found to be negligible in 

the plants (0.20-0.04%). 

                 A breif analysis of phytoconstituents of four Caesalpinaceae species was conducted by 

Awoyin et al., (2007).  In both water and ethanolic extracts of Cnidoscolus aconitifolius, eight 

major bioactive components were present in the dry leaf. Both extracts tested positive for three 

potent substances i.e. phenols, saponins and cardiac glycosides. Phlobatannin was found in the 

water extract, however alkaloids were found in the ethanolic extract. Both extracts were devoid of 

flavonoids, anthraquinones and mixed anthraquinones.  



7 
 

            Phytochemical analysis on the ethyl acetate fraction of an ethanolic extract of 

Pseudocedrella kotschyii leaf was assessed by Musa et al., (2008). They investigated flavonoids, 

glycosides and tannins as important chemical components. The extract included no alkaloids, 

saponins, cardiac glycosides or steroids. Qualitative analysis for phytochemicals in the leaf and 

root of four clinically essential plants e.g. Acalypha indica, Cassia auriculata, Eclipta alba and 

Phyllanthus niruri showed the presence of alkaloids, catechols, flavonoids, phenolic compounds, 

saponins and steroids in the root and leaf portions of Acalypha indica, but no anthroquinone, 

tannins or triterpenoids. Cassia auriculata root and leaf portions contained anthroquinone, 

alkaloids, flavonoids, phenolic compounds, saponins, steroids and tannins. The leaf and root of 

Eclipta alba contained phenolic chemicals, saponins, steroids, tannins and triterpenoids. 

Phyllanthus niruri root and leaf portions contained phenolic chemicals, anthroquinone, 

flavonoids, saponins, steroids, tannins and triterpenoids (Chitravadivu et al., 2009). 

The phytochemical analysis of leaf and stem of Cardiospermum helicacabum revealed a 

wide range of secondary metabolites (Viji and Murugesan, 2010). In all five solvent extracts of 

leaf and stem examined phenol, tannins and saponins were discovered in the highest 

concentrations, followed by steroids, sugars, flavonoids and terpenoids (Benzene and acetone). 

Leaf extracts in acetone and chloroform demonstrated greater inhibitory activity against 

Salmonella typhi and Streptococcus subtilis, respectively. Acetone extracts of the stem exhibited 

the strongest inhibitory effect on Salmonella typhi, whereas benzene extracts of the stem had an 

average inhibitory effect on Escherichia coli. In a separate investigation, the phytochemical 

contents of four plants Clerodendrum viscosum, Moringa oleifera, Cinnamomum tamala and 

Scoparia dulcis commonly utilized for various medical uses were compared. The active 

components revealed in these plants included alkaloids, tannin, saponin, terpenoid, flavonoid and 

cardic glycoside. Clerodendrum viscosum, Cinnamomum tamala and Moringa oleifera all had 

steroid, while laking in Scoparia dulcis. The experiment for quantifying phenols and ascorbic 

acids revealed that Cinnamomum tamala possessed the maximum concentration of phenol and 

ascorbic acids, whereas Clerodendrum viscosum possessed these substances in lowest 

concentration (Das and Chakraborty, 2011). 

                  The phytoconstituents of leaf extracts of Gymnema sylvestre, Phyllanthus amarus and 

Phyllanthus reticulatus were assessed. In our country, these herbs are utilised ethnomedically as 

anti-diabetic medicines. The experiment was conducted using three distinct extracts: ethanol, 

methanol and water. In the water extract of Phyllanthus amarus, they found terpenoids, 

flavonoids, phenol, quinines and catechin, as well as steroids, tannins, phenol and quinones in the 

ethanolic extract and just tannins, phenol and quinones in the methanol extract. The water extracts 

of Gymnema sylvestre contained terpenoids, alkaloids, flavonoids, saponins, tannins and 

quinones, whereas the methanolic extracts contained terpenoids, alkaloids, saponins, tannins and 

quinones. Only alkaloids, tannins and quinones were found in the ethanolic extracts. Phyllanthus 

reticulatus water extracts contained flavonoids, phenol and quinones. Steroids, tannins, phenol 



8 
 

and quinones were found in ethanolic extracts, while steroids, tannins, phenol and quinones were 

found in methanolic extracts (Gopinath et al., 2012). 

           Medicinal plants of diverse families, including Ficus religiosa, Citrus limonia, Phoenix 

dactylifera, Swertia chirata and Raphanus sativus, were investigated to identify and correlate 

their existence with plant bioactivities. All the six plants had tannins and flavonoids. Additionally 

apart from Phoenix dactylifera, terpenoids were found in all of the plant samples. Saponins and 

steroids elsewhere were lacking from all plants apart from Swertia chirata, while phlobatannins 

were not detected from all plants apart from Raphanus sativus. Carbohydrates, glycosides and 

coumarins were also found in all of the plants studied, apart from Phoenix dactylifera and 

Raphanus sativus. Except for Ficus religiosa, Phoenix dactylifera and Raphanus sativus, all of 

the plants studied contained alkaloids. Proteins were only discovered in Ficus religiosa and 

Swertia chirata, but emodins, anthraquinones, anthocyanins and leucoanthocyanins were lacking 

in all six plants studied. They determined that Swertia chirata has the best medicinal potentiality 

because it contains the maximum types of phytochemicals, whereas Phoenix dactylifera has the 

lowest medicinal efficacy since it lacks the potential phytochemicals (Yadav et al., 2014). Total 

phenolic and antioxidant tests on Adenanthera pavonina L. (family Mimosaceae) was conducted 

by Ghosh and Chowdhury (2015). Tribal people utilized the leaf and bark of this sample to treat a 

variety of maladies and disorders. For pharmacognostic examination of different portions of this 

plant, many criteria such as micromorphology, anatomy, phytochemical screening and physical 

constant were taken into account. Carbohydrates, proteins, alkaloids, glycosides, saponins, 

flavonoids, steroids, tannins and other compounds were detected in methanolic preparations of 

leaf and bark. Fenugreek (Trigonella foenum-graecum Linn.), an annual medicinal plant of family 

Fabaceae, is extensive used as TM. Extensive preclinical and clinical research has shown 

antibacterial, antifungal, anti-inflammatory, antiobesity and antioxidant pharmacological effects 

of fenugreek. The phytoconstituent analysis revealed the availability of alkaloids, steroids, 

polyphenols, flavonoids, saponins, carbohydrates, lipids, hydrocarbons and amino acids in the 

plant (Venkata et al., 2017). 

1.3.2. Antioxidant activity of plants 

The primary mechanism behind a variety of human neurological illnesses, hyperglycemia, 

inflammation, viral infections, autoimmune disorders and digestive system problems appears to 

be cellular imparement or oxidative damage caused by free radicals or reactive oxygen species 

(ROS) (Bardawell et al., 2018). Free radicals are produced as a result of regular pharmacological, 

environmental and other xenobiotic metabolism, as well as endogenous substances, particularly 

stress hormones (epinephrine and norepinephrine) (Das and Roychoudhury, 2014). According to 

accumulating research, ROS can be scavenged through chemoprevention using natural/synthetic 

antioxidant compounds. Antioxidants are compounds that counteract the effects of free radicals 

and they have long been utilized as primary health-protecting agents (Pham-Huy et al., 2008). 

Synthetic antioxidants have been linked to a variety of negative effects, thus the quest for natural 

antioxidants, particularly from botanicals, has accelerated in recent years (Ahmad et al., 2008). In 



9 
 

a study by Shyur et al., (2005), the antioxidative potential of twenty-six medicinal plant extracts 

were evaluated that are often used as traditional medicine in Taiwan. Between some of these 

plants Ludwigia octavalvis, Vitis thunbergii, Rubus parvifolius, Lindernia anagallis and 

Zanthoxylum nitidum were shown to have high DPPH activity, while Ludwigia octavalvis, Vitis 

thunbergii, Prunella vulgaris, Saurauia oldhamii and Rubus parvifolius had higher superoxide 

scavenging activity. Ludwigia octavalvis and Bombax malabaricum provided crutial defence 

against strand breakdown caused by UV irradiation H2O2 on ΨX174 super coiled DNA. In 

another research work, the total equivalent antioxidant capacity and phenolic content of twenty 

six popular spices ingredients from 12 different plants were assessed. Various spices with 

significant quantities of phenolic contents were found to correlation with having more antioxidant 

potential. Phenolic acids, phenolic diterpenes, flavonoids, volatile oils (e.g. aromatic compounds) 

and rosmarinic acid were among the phenolic elements found in the spice extracts, all of which 

were present in variable amounts. The total quivalent antioxidant capacity values and total 

phenolic content were found to have a strong positive linear relationship, indicating that phenolic 

substances in the evaluated spices may have dramatically increased their antioxidant activity 

(Shan et al., 2005). The antioxidant and free radical scavenging activitiy of crude methanolic 

extracts of 12 commonly used Indian medicinal herbs were investigated by Aqil et al., (2006). 

The extracts showed significant antioxidant and free radical scavenging action in varied degrees. 

The presence of phenolics, alkaloids, glycosides and tannins in the crude extracts was discovered 

by phytochemical analysis, which could explain the reported antioxidant effect. Total phenolic 

content and antioxidant capacity of 70 medicinal plant tinctures was investigated by Katalinic et 

al., (2006). The in vitro antioxidant assay was evaluated using standard assays such as Ferric 

reducing antioxidant power (FRAP), DPPH radical scavenging activity and ABTS activity. Out of 

various medicinal plants, Melissae folium was found to have the highest concentration of 

phenolics as well as the highest antioxidant activity, implying that the antioxidant potentiality is 

linked to the quantity of phenolics in the plant sample. 

           The antioxidant potentiality of methanolic crude extracts of certain regularly used 

medicinal herbs was investigated by Khalaf et al., (2008) and Rai et al., (2019). All methanolic 

fractions possessed substantial antioxidant capability which was found to be correlated with the 

presence of alkaloids, glucosides, tannins and flavonoids. In vitro antioxidant activity, total 

polyphenolic, flavonoid and flavonol content of petroleum ether, chloroform and methanolic 

extracts of Limonia acidissima Linn., leaf were investigated by Maleki et al., (2008). According 

to the findings, the methanolic extract had a high concentration of total polyphenolics, total 

flavonoids and total flavonols, which could explain its increased antioxidative potentiality. The 

antioxidant activity of methanolic extracts of Gmelina arborea Roxb. (Verbaneceae) was 

investigated by Patil et al., (2009). The extracts were shown to have strong antioxidant activity, 

which appeared to be connected to the phenolic content. The methanolic extract of plants 

commonly utilized as folk treatments by the tribes of the Attapady region was assessed for the 

antioxidant and radical scavenging activity (Sini et al., 2011). When compared to other plants 



10 
 

examined, Cassia occidentalis, Clitoria ternatea, Trianthema decandra, Capparis zeylanica, 

Anisomeles malabarica and Plumbago zeylanica all showed antioxidant potential, with 

Trianthema decandra having the greatest antioxidant potentiality. The results thus suggested 

medicinal potential of these plants.  

             The total phenolic and flavonoid content, as well as the antioxidative capacity of dried 

and powered leaf of Tinospora cordifolia were determined using different in vitro assays such as 

total reducing power, total antioxidant activity, lipid peroxidation inhibitory activity, DPPH 

radical scavenging activity and superoxide radical scavenging activity (Premanath and 

Lakshmidevi, 2010). Among all the solvent tested, the ethanol extract had the highest phenolic 

and flavonoid concentration, as well as antioxidant activity. The study concluded a relatively 

better extraction of active antioxidants in ethanol. 

                 The antioxidant property of Mucuna pruriens Linn., was investigated by (Satheesh et 

al., 2010). The antioxidant activity of the whole plant of Mucana pruriens in different solvents 

was tested by using in vitro DPPH (2, 2-diphenyl 1-picrylhydrazyl) radical scavenging activity, 

superoxide anion scavenging activity and iron chelating scavenging activity. The antioxidant and 

free radical scavenging activity of ethyl acetate and methanol extracts were found to be greater 

than those of the petroleum extract, which could be due to the presence of phenolic components in 

the former two extracts. 

              A similar study to assess the antioxidant capability and total phenolic content of 13 key 

medicinal plants was conducted by Narayanaswamy and Balakrishnan, (2011). The herbal 

extracts were prepared using solvents such as water and ethanol at a concentration of 5%. In all 

solvent systems, Ocimum basillicum leaf, Alpina calcarata leaf, Jatropa multifida flower, Hyptis 

suaveolens leaf, Solanum indicum leaf and Clitorria ternate leaf and flower showed increased 

DPPH radical scavenging activity. Ocimum basillicum and Clitorria ternate had the highest total 

phenolic contents. It was comcluded that the hydrogen donating ability of phenolics may be 

responsible for free radical scavenging function of medicinal plants. 

            One of the commercially available and most popular medicinal plants in the Himalayan 

region is Withania somnifera L., which is believed to have aphrodisiac property and can cure a 

variety of ailments. The antioxidant activity of Withania somnifera was investigated by Sharma et 

al., (2013). They had taken the plant from two different habitats in Kullu, North-West Himalaya, 

namely forest and roadside, and found that the plants' antioxidant activity differed significantly 

among the habitats. 

             Traditional medicine has employed Crataegus monogyna (hawthorn) leaf, flower and 

berry to treat chronic heart failure, high blood pressure, arrhythmia and numerous digestive 

illnesses, as well as geriatric and antiarteriosclerosis therapy. The water and ethanol extracts of 

leaf, flower and fruit of hawthorn was analyzed for H2O2 radical scavenging and total antioxidant 

activity (Keser et al., 2012). Both extracts were found to have significant antioxidant activity in 

the study. 



11 
 

            The phytochemical composition and antioxidant potentiality of methanolic extract of dried 

leaf of four medicinally significant herbs was assessed by Soni and Sosa, (2013). The herbs were 

Ocimum sanctum, Mentha spicata, Trigonella foenumgraecum, Spinacia oleracea and one 

medicinally essential tree Gmelina arborea used in the regular diet. Tannins, phlobatannin, 

saponins, flavonoids, steroids and alkaloids were found through phytochemical investigation. The 

leaf extract of Mentha spicata displayed the greatest antioxidant and reducing activity among the 

examined plants, which could be attributable to its phenolic content. 

               Cichorium glandulosum has long been utilized in China to treat degenerative and 

chronic disorders. The research work by Yao et al., (2013) reported the antioxidant activity, α-

glucosidase and α-amylase inhibitory activity and chemical composition of flavonoids from 

Cichorium glandulosum seeds using HPLC-ESI/MS. The plant showed substantial antioxidative 

activity against DPPH, ABTS, hydroxyl radicals and superoxide anion in vitro, as well as 

inhibitory effect against α-amylase and α-glucosidase. In vivo treatment of rats with flavonoids 

(100, 200, 400 mg/kg) resulted in a promising reduction in malondialdehyde levels, whereas 

superoxide dismutase and glutathione levels were regained to nearly basic levels and catalase and 

glutathione peroxidase levels highly rised in comparison to the group of rats consumed CCl4. Due 

to their antioxidant, anti-glucosidase and anti-amylase activity, C. glandulosum seeds may be 

given proper consideration as a food supplement or popular folk remedy. 

               Despite the fact that a large number of plants have been examined for antioxidant 

content, there are still considerable gaps in knowledge about various medicinal plants. The 

antioxidant property and phenolic substances of tropical plants from the Euphorbiaceae, 

Rubiaceae, Anacardiaceae, Scrophulariaceae and Poaceae families was examined by (Coulibaly et 

al., 2014). The research on various crude extracts of seven plant species found that substantial 

concentrations of phenolics present with the highest amounts in Feretia apodanthera and highest 

antioxidant activity found in Ozoroa insignis. An in vitro investigation of the antioxidant, 

antibacterial and anti-diabetic effects of polyphenols from Passiflora ligularis Juss. fruit pulp was 

evaluated by Saravanan and Parimelazhagan, (2014). To test biological potency, the plant was 

extracted in various solvents, such as petroleum ether, chloroform, acetone and methanol. In 

comparison to other extracts, the acetone extract had the highest concentration of phenolics, 

tannin and flavonoid. The acetone extract also had the highest in vitro antioxidative activity, such 

as metal chelating activity, FRAP and free radical scavenging activity, such as DPPH•, ABTS•+, 

O2•, •OH and NO• scavenging activity. Similarly, the acetone extract exhibited the greatest dose-

dependent antibacterial, α-amylase and α-glucosidase inhibitory activity. Gallic acid, caffeic acid, 

rutin, ellagic acid and kaempferol were found in varied amounts in the polyphenolic components 

after HPLC analysis. Eventually, a greater level of phenolic contents in the extract was correlated 

with more powerful antioxidant, antibacterial, α-amylase and α-glucosidase activity. Similarly, 

investigations conducted by Medini et al., (2014) on several Limonium delicatulum extracts 

demonstrated that the plant has powerful antioxidant and antibacterial property. The ethanol 

extracts exhibited the greatest overall antioxidant activity when compared to the other solvents, 



12 
 

acetone extracts had the highest capacity to scavenge free radicals and methanol extracts had the 

maximum suppression of β-carotene bleaching activity. 

               The antioxidant activity and total flavonoids content of aerial portions of Ficus 

pyriformis Hook. and Arn. (Moraceae) growing in Egypt was assessed by Ibraheim et al., (2015). 

Various fractions of Ficus pyriformis were tested for their ability to scavenge free radicals after 

being fractionated on vacuum liquid chromatography (VLC) with organic solvents of various 

polarities such as n-hexane, dichloromethane, ethyl acetate and methanol. Methanol and ethyl 

acetate fractions had the maximum potency between the extracts, followed by dichloromethane 

and n-hexane fractions. Steroids, triterpenoids, flavonoids, tannins, carbohydrates and/or 

glycosides were discovered through phytochemical study. The antioxidant potentiality of the 

methanolic extract and entire extract of Ficus pyriformis aerial parts contained polyphenolic 

substances including flavonoids and tannins, which have been shown antioxidant property. 

Similar experiments were carried out on the aerial sections of Teucrium barbeyanum Aschers. and 

antioxidant activity as well as chemical constituents were reported. It was shown that fractions 

containing a greater percentage of polyphenols had significant antioxidant activity, implying that 

Teucrium barbeyanum's antioxidant activity is linked to the presence of these substances 

(Mohamed et al., 2015). 

              The antioxidant potentiality of chloroform and ethanol fractions of four Indian medicinal 

plants like Grewia asiatica, Caesalpinia bonducella, Syzygium samarangense and Asteracantha 

longifolia was evaluated. The antioxidant capacity of these plant extracts varied dramatically 

(Madhura et al., 2015). The four plant seeds of Asteracantha longifolia were found to have high 

antioxidant property. Siqun et al., (2015) evaluated the antioxidant potentiality, anticancer impact 

and antiaging activity of proanthocyanidins extracted from Kunlun chrysanthemum flower 

(PKCF) found in Xinjiang. The principal component of Kunlun chrysanthemum in the Chinese 

market is dry tea, which entirely lacks refinery processing and is believed to have a variety of 

medical advantages. Both in vitro and in vivo analysis have demonstrated the exceptional 

antioxidant property, which is higher than that of vitamin C. In mice in vivo and in Drosophila, 

the extract was found to decrease malondialdehyde production while increasing superoxide 

dismutase activity. It has strong antitumor action, as it could suppress the proliferation of H22, 

Eca-109 and HeLa cancer cells at minimum doses, with IC50 values of 70.96 ± 0.05409 μg/ml, 

260.4 ± 0.06887 μg/ml and 113.3 ± 0.08062 μg/ml, respectively. Because of its significant 

antioxidant capability, PCKF was proposed as a novel antioxidant to be used in food and 

pharmaceuticals. The antioxidant capability of several extracts of Phoenix dactylifera L., which 

has been used to cure a number of diseases in many conventional systems of drug in Southwest 

Asia and North Africa, were described by (Eddine et al., 2015). The FRAP, superoxide radical 

scavenging (O2) and DPPH radical scavenging capacity assays were used to determine the 

antioxidant activity of ethanol, methanol, hexane and chloroform fractions. The experiments 

found a pronounced positive relation between DPPH radical scavenging capacity of the extracts 

and phenolic content, as well as a substantial correlation between FRAP values and total 



13 
 

proanthocyanidins content. Ethanol had stronger phenolics and antioxidative property than the 

other extracts, which was thought to be due to the existence of phenolics in the extracts. The hill-

mango, Commiphora caudata Engl. (Syn. Protium caudatum Wight and Arn.), belonging to the 

Burseraceae family and blooms in the arid or moderate-evergreen habitats of South India. The 

plant has been seen to perform a variety of biological activity (Sivakumar et al., 2009; Annu et 

al., 2010). Reddy et al., (2015) assessed in vitro experiments to study the chemical constituents, 

antibacterial and antioxidant property of C. caudata essential oils obtained from leaf and fruit to 

further investigate the therapeutic activity of the plant. The findings revealed the existence of 

fifteen chemicals in leaf oil and thirty substances in fruit oil and both the oil fraction showed 

significant antibacterial and antioxidant potentiality to differing levels. 

The chemical compositions and antioxidant evaluation of the essential oils (EOs) 

obtained by hydrodistillation from the leaf and stem of Indigofera spicata Forssk (Fabaceae) 

grown in Nigeria have been studied by Adeleye et al., (2021). Methanolic extract of Xylocarpus 

moluccensis was found to be significantly effective in scavenging DPPH and ferric reducing 

antioxidant activity was tested by Budiarso et al., (2021). The phytochemical test of Origanum 

vulgare ethanol extract was showed some phytochemicals, such as a flavonoid, alkaloid, 

triterpenoid, steroid, essential oil, tannin, ethyl acetate and hexane. Additionally in vitro assay 

showed that Origanum vulgare extract has strong antioxidant activity with an IC50 value of 

133.47 μg/ml (Rosmalena et al., 2021).  Flavonoid content and antioxidant potential of leaf 

extracts of Passiflora setacea was reported by Santos-Tierno et al., (2022). Phytochemical 

analysis and antioxidant activity of Cotinus coggygria (Smoke tree) was evaluated. The amount 

of flavonoid in ethanol extract of C. coggygria, growing in Armenia, was 0.94%. In volatile oil of 

the plant leaf 22 compounds were identified and among them the Germacrene D, Linalool, 

formate, ά–Terpineol sesquiterpenes and diterpene alcohol were predominant. The essential oil of 

Cotinus leaf also showed antioxidant activity (Shaboyan et al., 2021). 

1.3.3. Antimicrobial activity of plants 

Plants produce antimicrobial substances as part of their defensive strategy against pests and 

diseases, as is widely documented. Several researchers have published various research articles on 

extracting plant based antimicrobial chemicals and test against microorganisms in vitro with the 

goal of using them as a source of pharmaceuticals (Vaou et al., 2021). 

         The disc diffusion method utilized to test the antibacterial activity of crude and methanol 

extracts of Terminalia bellerica dry fruit against nine human bacterial pathogens was evaluated 

by Elizabeth, (2005). Both of the crude and methanolic extracts were reduced the proliferation of 

the examined pathogens to varied degrees. Except for Escherichia coli and Pseudomonas 

aeruginosa, methanolic extract was more productive than crude extract against most of the 

microorganisms studied. Among the bacteria studied, Staphylococcus aureus was shown to be the 

most sensitive to both extracts, implying that Terminalia bellerica is a significant inhibitor of this 

pathogen. The minimal inhibitory concentrations (MICs) of crude extracts varied from 300 to 

>2400 g/ml, whereas MICs of methanolic extracts varied from 250 to >2000 g/ml, with the least 



14 
 

MIC value against Staphylococcus aureus, indicating that arid fruit of Terminalia bellerica has 

significant broad spectrum antibacterial action. Antibacterial activity of aqueous, ethanolic, 

methanolic and phenolic fractions derived from three Palestinian traditional medicinal plants, as 

well as their industrial oils, against ten pathogenic microbes was evaluated. In Palestine, sage, 

hyssop and madder have long been utilized as traditional remedy to cure a variety of disorders. 

The antimicrobial potentiality of plants was assessed and evaluated against E. coli, Proteus 

mirabilis, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Actinobacter 

haemolyticus, Enterococcus sp. and Candida albicans extracted from UTI (urinary tract 

infections) patients, as well as Salmonella typhi and Staphylococcus aureus isolated from the 

stool of food poisoning patient. The sage and hyssop derived from the aqueous extracts were 

found to be productive against the majority of the bacteria have been tested. The phenolic extracts 

of sage and hyssop were found to be sensitive against Staphylococcus aureus and Enterococcus 

sp, respectively. Additionally the ethanolic extract of madder was more sensitive against 

Escherichia coli, but had no potency on the Gram positive bacteria. Escherichia coli, Proteus 

mirabilis and Salmonella typhi were not restricted by industrial oils of sage, hyssop or madder. 

Staphylococcus aureus was found to be the most vulnerable bacterium to maximum extracts of 

the three plants studied out of the ten studied bacteria. The findings support the traditional 

therapeutic usage of hyssop, sage and madder for the treatment of microbial diseases such as 

UTIs and foodborne disease caused by bacteria (El Astal et al., 2005). 

             Bidens pilosa L., Bixa orellana L., Cecropia peltata L., Cinchona officinalis L., 

Gliricidia sepium H.B. and K, Jacaranda mimosifolia D. Don, Justicia secunda Vahl., Piper 

pulchrum C. DC, Piper paniculata L., and Spilanthes americana L. plants were assessed for 

antibacterial activity against five bacteria: Staphylococcus aureus, Streptococcus β hemolyticus, 

Bacillus cereus, Pseudomonas aeruginosa and Escherichia coli. and one yeast (Candida albicans) 

(Rojas et al., 2006). The findings revealed that all of the plants tested were potent against three or 

more harmful bacteria, but impotent against Streptococcus hemolyticus or Pseudomonas 

aeruginosa. The study also revealed that Bixa orellana L., together with Justicia secunda Vahl. 

and Piper pulchrum C. DC, could be potential sources of novel antimicrobial compounds, 

promoting the utilization of traditional medicinal plants as antimicrobial substances. Agyare et al., 

(2006) evaluated that both methanolic and petroleum ether extracts of the leaf and bark of 

Nauclea latifolia, Bridelia atroviridis and Zanthoxylum gilletii possessed antimicrobial activity 

when screened against six microbs, including Escherichia coli, Pseudomonas aeruginosa, 

Staphylococcus aureus, Bacillus subtilis, Candida albicans and Aspergillus niger, but that 

methanolic extracts were more potent than petroleum ether. 

          Psidium guayava and Mangifera indica were reorted by Akinpelu and Onakoya, (2006) to 

determine their antibacterial property. In the South Western portion of Nigeria, these two plants 

are commonly utilized for herbal medicines to cure odontalgia, gastrointestinal issues, dynsentery, 

diarrhoea, painful gums and sore throats. Both plant extracts were found to be capable of reducing 



15 
 

the proliferation of all fifteen various bacteria employed to variable degrees, although Psidium 

guajava was found to be more significant. 

            The antimicrobial property of 18 ethnobotanical plant extracts against nine bacterial 

strains (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus 

faecalis, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Ervinia sp.) was 

investigated by Duraipandiyan et al., (2006). Methanolic extracts of Acalypha fruticosa, 

Peltophorum pterocarpum, Toddalia asiatica, Cassia auriculata, Punica granatum and Syzygium 

lineare were shown to be most effective than the hexane extracts among the plants studied. 

Methanolic extracts of Peltophorum pterocarpum and Punica granatum have the significant 

antifungal efficacy against Candida albicans (Parveen et al., 2010). 

            The extracts of Bryophyllum pinnatum and Kalanchoe crenata possessed midium 

antimicrobial property against gram-negative bacteria (Escherichia coli, Pseudomonas 

aeruginosa, Klebsiella pneumoniae, Shigella flexneri, Salmonella paratyphi, Citrobactor sp.) and 

gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis) was 

found by Odunayo et al., (2007). In a related experiment conducted by Ushimaru et al., (2007) to 

determine the in vitro antibacterial potentiality of different plant extracts i.e. Allium sativum, 

Zingiber officinale, Caryophyllus aromaticus, Cymbopogon citratus, Mikania glomerata and 

Psidium guajava against Gram-positive and Gram-negative bacterial pathogen obtained from 

human infections. The study revealed that all of the extracts showed different levels of 

antimicrobial activitiy. Out of those plants, Caryophyllus aromaticus showed the significant 

effect. 

         The antibacterial and antifungal property of several of the native plants in Mysore, including 

Acacia nilotica, Sida cordifolia, Tinospora cordifolia, Ziziphus mauritiana and Withania 

somnifera was tested by Mahesh and Satish, (2008). The study found that all sections of the plants 

were effective to varied degrees against bacterial and fungal pathogens. Likewise, Islam et al., 

(2008) conducted a through investigation and reported the antibacterial property of various native 

flora of Bangladesh that tribal public in Chittagong had been using to cure infectious diseases. 

Only five plants, out of the total 16 plants i.e. Mentha arvensis, Enhydra fluctuans, Blumea 

lacera, Chenopodium album and Glinus oppositifolius, exhibited antibacterial action at various 

levels against Shigella dysenteriae, Salmonella typhi, Salmonella paratyphi, Bacillus cerus, 

Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Vibrio 

cholera and Bacillus megaterium.  Furthermore, gram positive bacteria were more vulnerable to 

the crude extracts than gram negative bacteria and Blumea lacera might show more activity 

compared to the other plants. 

               The antibacterial activitiy of severel commonly used therapeutic flora such as Ocimum 

sanctum, Origanum majorana, Cinnamomum zeylanicum, and Xanthoxylum armatum against 

various bacterial pathoges such as Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, 

Staphylococcus aureus, Pseudomonas sp., Proteus sp., Salmonella typhi, Escherichia coli, 

Shigella dysentriae and Klebsiella pneuminiae were assessed. The results revealed that the 



16 
 

effectiveness of these plants against bacterial pathogens varied significantly. Out of them 

Origanum majorana showed the most potent activity. Gram-positive bacteria have been found to 

be more vulnerable than gram-negative bacteria (Joshi et al., 2009). The antibacterial and 

antioxidant capability of Inula aucherana, Fumaria officinalis, Crocus sativus, Vicum album, 

Tribulus terestris, Polygonatum multiflorum, Alkanna tinctoria and Taraxacum officinale against 

severel microorganisms was tested by Sengul et al., (2009). Almost all of the plants exhibited 

varying degrees of antioxidant and antibacterial property. The potentiality of methanolic extracts 

was found to be higher than that of aqueous extracts. Because total phenolic concentration did not 

correspond with antioxidant ability, it was inferred that phenolic chemicals were not the primary 

cause of the extracts' antioxidant ability. Indeed, various additional phytochemicals, including as 

ascorbic acid, tocopherol and pigments, may be thought to contribute to total antioxidant activity 

in a synergistic way. 

            In additional research, the methanolic extract of Oldenlandia umbellata showed 

antibacterial ability against pathogens obtained from respiratory tract infections. The research 

revealed that both gram positive and gram negative bacteria may be efficiently restricted by the 

root and leaf of this plant. Seven distinct anthraquinones were found in the methanolic extract of 

the plant, with the 1-2- dihydroxy anthraquinone known as Alizarin being the most abundant. 

Plant based Alizarin and synthetic Alizarin were shown to be similarly potential to restrict the 

bacterial proliferation (Arun et al., 2010). 

               The antifungal property of different medicinal plants, including Andrographis 

paniculata, Valeriana jatamansi, Asparagus racemosus, Tinospora cordifolia, Coleus barbatus, 

Berberis aristata, Achyranthes aspera and Plantago depressa against harmful fungus was tested 

by Mathur et al., (2011). The research revealed that all of the plants showed varying levels of 

antifungal activity, with hydro-alcholic extracts being more powerful than hexane extracts. 

Hydro-alcoholic extracts of Andrographis paniculata and Achyranthes aspera were found to 

restrict efficiently the proliferation of Aspergillus niger and Candida albicans. 

         The antimicrobial potentiality of severel medicinal plants i.e. Asphodelus tenuifolius, 

Asparagus racemosus, Balanites aegyptiaca, Cestrum diurnum, Cordia dichotoma, Eclipta alba, 

Murraya koenigii, Murraya koenigii, Peladium murex, Richinus communis and Trigonella foenum 

graecum against bacterial pathogens obtained from oral cancer like Staphylococcus aureus, 

Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumonia, 

Proteus mirabilis, Proteus vulgaris and the pathogenic fungus like Candida albicans and 

Aspergillus fumigates was investigated by Panghal et al., (2011). The findings revealed that eight 

out of the ten medicinal plants studied had efficient antimicrobial ability against the majority of 

the bacteria, with Pseudomonas aeruginosa being the most vulnerable bacterium, suggesting that 

therapeutic plants could be used as a significant antimicrobial substance to restrict secondary 

infections in cancer patients. The antimicrobial property of chloroform: methanol (1:1) extracts of 

numerous Helichrysum species against three Gram-positive bacteria (Bacillus cereus, 

Staphylococcus aureus and Staphylococcus epidermidis), two Gram-negative bacteria (Klebsiella 



17 
 

pneumoniae and Pseudomonas aeruginosa) and one fungus (Cryptococcus neoformans) was 

evaluated by Lourens et al., (2011). At the similar concentration, seven out of those studied plants 

had minimum inhibitory concentrations of less than 0.1 mg/ml against Bacillus cereus and/or 

Staphylococcus aureus, and less than 25% growth for the Graham and MCF-7 cell lines. 

              The antibacterial and antifungal property of crude extracts of Withania somnifera fruit 

coat (calyx) in various solvents (hexane, petroleum ether, toluene, benzene, isopropyl alcohol, 

chloroform, ethyl acetate, acetone, ethanol, glacial acetic acid and water) against both plant and 

human pathogens like Proteus merabilis, Klebsiella pnemoniae, Agrobacterium tumefaciens 

(plant pathogen) and one fungus Aspergillus niger was investigated by Singariya et al., (2012). 

The findings revealed that 9 out of 11 extracts were effeicient against bacterial and fungal 

proliferation, demonstrating Withania somnifera's vast range nature. The antibacterial activity of 

ethyl acetate, glacial acetic acid, isopropyl alcohol and chloroform extracts were the highest, 

while glacial acetic acid exhibited remarkable potency with a quite low MIC and MBC/MFC 

values that were equal to the standard medicines utilized (gentamycin and ketoconazole). The 

antibacterial activity of the genus Murraya koenigii (Mitha neem) leaf, one of the most often 

utilized aromatic substances in Indian cuisine was tested by Harish et al., (2012). The herbs have 

been utilized as folk medicines for centuries and are said to have antibacterial, anti-inflammatory, 

anti-feedant and other properties (Dahanukar et al., 2000). The study found that water, ethanol, 

chloroform and petroleum ether extracts possessed antimicrobial property against gram positive 

(Staphylococcus aureus) and gram negative (Pseudomonas aeuriginosa, Escherichia coli, 

Klebsiella pneumonia and Salmonella typhi) bacteria at different levels. These four extracts 

showed MIC ranging from 12.5 to 50.0 mg/ml, whereas the minimum bactericidal concentration 

(MBC) was from 50.0 to 100.0 mg/ml. The ethanolic extract, on the other hand, possessed the 

highest bactericidal impact compared to all of the extracts. Murraya koenigii considered as an 

antibiotic source due to the presence of carbazole alkaloids which was thought to be antibacterial 

substance. Antifungal potentiality of ethanolic, methanolic and distilled water extracts of Blumea 

lacera against Aspergillus niger, Aspergillus oryzae, Aspergillus praraciticus-456, Aspergillus 

flavus and Aspergillus parasiticus at different concentrations was investigated by Kagne et al., 

(2012). The activity of ethanolic extract was higher when compared with the other extracts, which 

could be due to the chemical subtances such as oils present in the sample.  

         The antibacterial efficacy of Rivea ornata methanolic extract against bacterial strains i.e. 

Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli were 

investigated by Sharma and Patel, (2013). The antibacterial efficacy of Amaranthus spinosus, 

Orchis muscula and Solanum nigrum against Staphylococcus aureus, Streptococcus mutans, 

Bacillus subtilis, Bacillus amylolique faciens, Aspergillus fumigates and Escherichia coli was 

evaluated. Methanol, acetone and hexane extracts of Amaranthus spinosus, Solanum nigrum and 

Orchis muscula showed antibacterial efficiency at different degrees. Although, methanolic 

extracts showed the best antibacterial activity when compared with the other extracts, whereas 

chloroform extract proved ineffective against the bacterial pathogens. Phytochemical research 



18 
 

indicated the methanolic extracts possessed tannins and flavonoids but those are not present in 

chloroform extracts, which could have influenced to the superior antibacterial action of 

methanolic extracts, hence supporting the plants' traditional use (Thalwal et al., 2013). The 

antioxidant, antibacterial and phytochemical property of various raw extracts of Datura metel 

accessible in the Sultanate of Oman, in various solvent i.e. hexane, ethyl acetate, chloroform, 

butanol and methanol was examined by Alabri et al., (2014). All of the raw extracts of both arid 

and fresh leaf were shown to have different levels of antibacterial and antioxidant actions in the 

research. The methanolic extracts, on the other hand, were slightly more effective in reducing the 

proliferation of one gram positive (Staphylococcus aureus) and three gram negative bacteria 

(Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa). Phytochemical 

screening demonstrated the existence of alkaloid, flavonoid, saponin and tannin components in all 

raw extracts of both arid and fresh leaf, but no steroids and triterpenoid. Antioxidant and 

antibacterial actions may have been produced by the existance of phytochemicals such as tannins 

and flavonoids. 

            The antibacterial activity of the medicinal plant Rhinacanthus nasutus Linn., was 

conducted by Nanthakumar et al., (2014). The study found that the aqueous and ethanolic extracts 

of Rhinacanthus nasutus showed antimicrobial potency against Bacillus subtilis, Streptococcus 

faecalis, Salmonella paratyphi, Aspergillus flavus, Candida albicans, Trichoderma viride, 

Bacillus subtilis and Pencillium sp. at different levels those are human pathogenic microbes. The 

aqueous extract, on the other hand, exhibited significant action against Bacillus subtilis, 

Salmonella paratyphi, Candida albicans and Aspergillus flavus than the ethanolic extracts, 

creating it a viable optional antimicrobial substence to inhibit the pathogens that developing 

infection. The antioxidant and antibacterial effects of several Sonneratia alba extracts in an 

another investigation was demonstrated by Haq et al., (2014). The ethanolic and aqueous extract 

of this plant bark exhibited the potent antioxidative and antibacterial effects when compared with 

all of the other extracts. Maximum phenolic concentration in the sample, may have related to the 

potent biological properties. The phytochemical and antibacterial properties of several therapeutic 

floras against five bacterial pathogens that cause oral infections were tested by Gauniyal and 

Teotia, (2014). Nearly all of the plants investigated showed antibacterial action against 

Streptococcus mutans, Enterococcus faecalis, Lactobacillus acidophilus, Candida albicans and 

Candida tropicalis. Although, Acacia nilotica, Citrus limon, Emblica officinalis, Juglans regia, 

Psidium guajava L., and Withania somnifera were shown to be successfully suppress the 

microbial proliferation, while Lannea coromandelica (Houtt) Merr and Rosa centifolia were 

found to faintly restrict the microbial proliferation. Phytochemical screening showed alkaloids, 

glycosides, terpenoids, steroids, flavonoids, tannins, reducing sugars and saponins were found in 

nearly all of the tested plants, selecting these plants as viable source for the production of 

antimicrobial drugs against oral pathogens. Similarly, Tirupatirao et al., (2014) assessed the 

antibacterial actions of different extracts i.e. water, methanol and petroleum ether of two 

therapeutic plants in our country, Ocimum sanctum and Azadirachta indica, against Bacillus 



19 
 

subtilis, Staphylococcus aureus, Escherichia coli, Micrococcus luteus and Pseudomonas 

aeruginosa. Each and every extracts were capable to restrict the proliferation of the pathogens at 

different levels. On the other hand, the methanolic extract of Azadirachta indica and the water 

extract of Ocimum sanctum exhibited significant antibacterial efficacy compared to the petroleum 

ether extract. 

              The antibacterial potentiality of ethanolic fractions of sixteen folk medicinal plants in 

Nepal was tested against 13 pathological and 2 reference bacterial strains by Marasini et al., 

(2015). The findings revealed that the plants showed antimicrobial activity at different levels. 

Among the selected plants, Cynodon dactylon considered as the most effective plant that reduce 

the proliferation of indeed the methicillin-resistant Staphylococcus aureus, imipenem-resistant 

Pseudomonas aeruginosa, multidrug-resistant Salmonella typhi and Salmonella typhimurium. 

Additionally, the ethanolic extracts of Cinnamomum camphora, Curculigo orchioides and 

Curcuma longa exhibited the greatest MIC values against Strepcoccus pyogenes, whereas the 

chloroform fraction of Cynodon dactylon showed the significant antibacterial effect against 

Staphylococcus aureus. Cynodon dactylon, Cinnamomum camphora, Curculigo orchioides and 

Cucurma longa extracts with MIC values less than 100 μg/ml could be thought as a substantial 

source of antibacterial drug against diseases caused by multi-drug resistence bacteria. The 

antibacterial efficacy of Morus indica leaf extract against Staphylococcus aureus, Aspergillus 

niger and Penicillium was evaluated by Chaitali et al., (2015). The antibacterial and antifungal 

efficiency of the ethanolic and methanolic extracts was superior, which could be attributable to 

the existance of different additional metabolites in the leaf of Mangifera indica. Londhe et al., 

(2015) found that leaf of Ocimum tenuiflorum, Ocimum gratissimum and Ocimum 

kilimandscharicum possessed antimicrobial action against Bacillus cereus, Bacillus subtilis, 

Escherichia coli, Pseudomonas aeruginosa and Aspergillus niger. Antimicrobial effect was found 

in all of the three Ocimum species at different levels. Although, Ocimum kilimandscharicum 

exhibited significant antibacterial action against Bacillus cereus, Escherichia coli and 

Pseudomonas aeruginosa, whereas Ocimum gratissimum leaf extract was efficient against 

Aspergillus niger. Reducing sugars, monosaccharides, hexose sugar, amino acids, tannins and 

phenolic compounds, citric, malic and tartaric acids were found in primary phytochemical 

screening. 

           Phytochemical analysis, antioxidant and anti-microbial activity of Suaeda vermiculata 

were evaluated. The n-hexane extract contained twenty four compounds with bornyl acetate, γ-

elemene and phytol constituting 73.74 % of the extract. At a concentration of 10 mg/ml, the n-

hexane extract inhibited DPPH-radicals with a 27% efficiency, which was less effective than the 

volatile oil's DPPH reactivity. Except for Candida albicans, which showed inhibition zone 

diameter values of 19 mm with MIC values at 5.2 mg/ml for the volatile oil while inhibition zone 

diameter values of 26 mm and MIC values at 4.7 mg/ml were observed for the n-hexane extract, 

thus the antimicrobial activity of n-hexane extract was relatively weaker than the volatile oil (Al-

Omar et al., 2021). Antioxidant and antimicrobial activity of methanolic leaf extract of Aegle 



20 
 

tamilnadensis revealed the presence of phenols and flavonoids as major phytochemicals and it 

possessed significant antioxidant and antimicrobial activity against Staphylococcus aureus and E. 

coli (Chellakumar et al., 2017). Antibacterial activity of leaf and seed extract of Carica papaya 

against Pseudomonus aeruginosa and E. coli assessed by Dagne et al., (2021). They found seed 

with ethanol extract showed highest antibacterial activity against Pseudomonus aeruginosa 

whereas lowest inhibition was recorded from leaf ethanol crude extract against E. coli. In vitro 

antibacterial activity of Psidium guajava leaf extract against Klebsiella pneumonia was evaluated 

by Hackman et al., (2020). The investigation revealed that the ethanolic extract of guava leaf had 

MIC and MBC of 6.25 mg/ml, both of which indicated strong antibacterial activity against the 

carbapenem-resistant K. pneumoniae. Because the guava leaf extract contains flavonoids and 

other antimicrobial phytochemicals, it may be responsible for the antibacterial activity of the 

extract from the leaf. The results of these initial laboratory investigations point to the potential for 

developing effective antibiotics to treat carbapenem-resistant systemic illnesses. Jude et al., 

(2020) found various phytochemicals like alkaloids, flavonoids, tannins, terpenoids, cardiac 

glycosides and reducing sugar from methanol extract of Garcinia Kola. The extract also exhibit 

effective antimicrobial activity against four pathogenic bacteria e.g. Staphylococcus aureus, 

Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and two fungus like Candida 

albicans and Aspergillus niger. Anti-bacterial activity of isolated compounds i.e. pyrethrin II, 

jasmolin I and cinerolone from Chrysanthemum cinerariaefolium against methicillin-resistant 

Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus aureus and Shigella sonnei 

was studied by Kosgei et al., (2021). Phytochemical screening of methanol extract of Curcuma 

longa showed the presence of alkaloids, phenols, saponins, steroids, tannins, glycosides and 

flavonoids. This study was also carried out to assess the antimicrobial potential of the methanolic 

extract of Curcuma longa rhizome against seven clinical isolates including Staphylococcus 

aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans, 

Aspergillus flavus and Fusarium species (Maduakor et al., 2022). The stem bark of Khaya 

grandifoliola and its ethanol extract possessed tannins, alkaloids, saponins, reducing sugars, 

flavonoids, terpenoids and phenols, according to a preliminary phytochemical screening. Using 

the agar well diffusion method, the antibacterial activity of its ethanolic extract was assessed 

against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Klebsiella 

pneumoniae. DPPH radical scavenging activity and total antioxidant capacity of its ethanolic 

extract also assessed (Quartey et al., 2020). Phytochemical composition of Buchholzia coriacea 

and Psychotria microphylla leaf extracts revealed to possess minerals, alkaloids, protein, 

terpenoids, phenols, flavonoids, glycosides, steroids, tannins and vitamins. These plant extracts 

also used to study antibacterial activity against bacterial isolates from the water bodies like 

Aeromonas hydrophila, Escherichia coli and Vibrio cholera (Ude et al., 2021). Phytochemical 

composition of Syzygium polyanthum methanolic leaf extract consists of alkaloids, saponin, 

terpenoids and steroid. Additionally antibacterial activity was tested against four bacterial 



21 
 

pathogens like Staphyloccous aureus, Streptococcus pyogenes, methicillin-resistant 

Staphylococcus aureus and Klebsella pneumonia was demonstrated by Wahab et al., (2021).  

            The effectiveness of leaf extracts from several South African plant species (Bucida 

buceras, Breonadia salicina, Harpephyllum caffrum, Olinia ventosa, Vangueria infausta and 

Xylotheca kraussiana) against a variety of phytopathogenic fungi was examined (Aspergillus 

niger, Aspergillus parasiticus, Colletotricum gloeosporioides, Penicillium janthinellum, P. 

expansum, Trichoderma harzianum and Fusarium oxysporum). These plant infections, which 

include blue rot on stamens and postharvest disease in citrus, generated significant financial 

losses in the fruit business. 600 plant species were chosen and tested against two animal fungal 

diseases, among other things (Candida albicans and Cryptococcus neoformans) (Mahlo et al., 

2016). 

1.3.4. Hypoglycemic activity of plants 

Diabetes mellitus is a severe and fatal disorder characterized by increased blood glucose level 

caused by reduction of insulin production, insulin resistance and modified carbohydrate, lipid and 

protein metabolism which can contribute to additional difficulties such as chronic kidney failure, 

retinal damage, cardio-vascular and neuro-degenerative disorders (Tomic et al., 2022). Apart 

from breakthroughs in diabetes management and awareness, the occurrence of disease and 

disease-related complications appears to be increasing at a serious rate. Various medicines are 

used to treat diabetes and oxidative stress has been linked to a variety of side effects, prompting a 

worldwide hunt for plants with therapeutic activity (Inas et al., 2011). In this point of view, 

hypoglycemic efficiency of Murraya koenigii leaf water extract in normal and alloxan-induced 

diabetic rabbits was evaluated by Kesari et al., (2005). The findings revealed that a single oral 

treatment of different dose contents (200, 300, and 400 mg/kg body weight (BW)) of the water 

extract was effective in decreasing blood sugar levels in both normal and diabetic rabbits. 

Murraya koenigii leaf have long been used as a spice for food essence and are considered as 

secure component to eat, thus they could be given as a supplement to other diabetic therapy such 

as dietary therapy and pharmacological therapy. 

            The research by Rao and Nammi's, (2006) backs up the traditional use of Terminalia 

chebula (Combretaceae) to cure diabetes. They used short and long term research procedures to 

assess the anti-diabetic and renal function-protecting effects of the chloroform extract of 

Terminalia chebula in STZ-induced diabetic rats. Administering the extracts orally to STZ-

induced diabetic rats at dosages of 100, 200 and 300 mg/kg in a trial of brevity and (300 mg/kg) 

in a lenthy research (daily for 8 weeks) was demonstrated to considerably lower blood glucose 

levels and showed considerable renoprotective effect. The lowering of blood glucose by 

Terminalia chebula can be attributed to either enhanced insulin production from Islets β-cells or 

an additional pancreatic pathway; although, the pathway of renoprotection remains unknown. The 

impact of Dorstenia picta methanolic extract on blood glucose levels and a few biochemical 

parameters in normal and STZ-induced diabetic rats was studied by Florence et al., (2007). The 

findings revealed that a combination of Dorstenia picta methanolic extract and insulin might 



22 
 

arrest the loss of body weight, polyphagia and polydipsia. The extract, when given at doses of 75 

mg/kg and 150 mg/kg, was found to decrease blood glucose levels in diabetic rats effectively by 

53.88% and 81.96% (p˂0.01). Additionally, serum cholesterol, triglycerides, plasma SGOT and 

SGPT levels were effectively reduce in both normal and diabetic rats, whereas creatinine and total 

protein level remain unchanged. According to the authors, administration with Dorstenia picta 

extract may enhance glucose homeostasis in STZ-induced diabetes by perhaps insulin related 

action and ameliorating kidney and liver functions. The hypoglycemic impact of Anacardium 

occidentale Linn., in STZ-induced diabetic rats in a comparable study was evaluated by Sokeng et 

al., (2007). The experiment found that when methanolic extract administered orally at doses of 

35, 175 and 250 mg/kg, after 3 h it lowered blood glucose levels in diabetic rats efficiently with 

highest decrease of 37 and 35% at doses 175 and 250 mg/kg, respectively. Repeat delivery of 

methanolic extracts and their fractions, as well as n-hexane, dichloromethane and ethyl acetate 

fractions, dramatically lowered blood glucose levels by 21-48%, as well as urine glucose levels. 

Hexane and ethyl acetate portions of the extracts had the strongest effects, which could be 

attributed to the plant's non-polar and polar hypoglycemic chemicals. 

            The in vitro anti-diabetic and antioxidant actions of Cirsium japonicum roots, was 

investigated by Jie et al., (2008). In Korea, the herb has been utilized as an antihemorrhagic, 

antihypertensive and antihepatitis substence. The methanolic and aquoeus extracts of Cirsium 

japonicum roots showed antioxidant activity at different levels. The methanolic extract being 

more powerful when compared with aqueous extract. Although, methanolic extract possessed no 

α-glucosidase inhibitory action, the aqueous extract possessed medium inhibitory effect on α-

glucosidase, despite the methanolic extract having higher phenolic and flavonoid substance. The 

antidiabetic efficacy of both the leaf and callus collected from Aegle marmelos leaf explants was 

assessed by Arumugama et al., (2008). In STZ-induced diabetic rabbits, both the leaf and the 

callus were found to dramatically lower blood sugar levels. The methanolic extracts of the leaf 

and callus showed the highest anti-diabetic activity when compared with other extracts. 

              The anti-diabetic properties of the methanol extract of Artanema sesamoides Benth., in 

STZ-induced diabetic rats were investigated. The extract at doses of 200 and 400 mg/kg BW 

efficiently lowered fasting blood glucose levels while raising liver glycogen levels (25.84 ± 1.52 

mg/ml) when compared to diabetes control (12.31 ± 0.63 mg/ml) (P˂0.001). Moreover, there was 

a maximum decline in the serum SGOT, SGPT and alkaline phosphatase activity than that of 

diabetic rats. On the other hand, the extract exhibited cytoprotective action as validated by a 

considerable reduction in cholesterol and triglycerides contents, as well as a progress in the 

HDL/LDL ratio (Sengul et al., 2009).  In a similar study, Prasad et al., (2009) tested the anti-

diabetic effect of water leaf extracts of three medicinal plants i.e. Murraya koenigii, Psidium 

guajava and Catharanthus roseus, in diabetic albino rats induced by STZ. Single oral 

adminidtration of these extracts at dose of 500 mg/kg BW daily for 15 days were found to lower 

blood sugar levels (p˂0.001) efficiently and raise body weight in regard to diabetes control after 

15 days. Additionally, histological architecture that was changed during diabetic symptoms was 



23 
 

regained in a way that was equivalent to the conventional drug glibenclamide, which is used to 

treat diabetes. Methanolic extract of Vinca rosea (Catharanthus roseus) showed anti-diabetic 

effect in alloxan-induced diabetic rats (Ahmed et al., 2010). Nearly all plant components of Vinca 

rosea have been utilized to treat numerous ailments in the past and have been scientifically 

confirmed (Cowley and Bennet, 1928; Pillay et al., 1959; Nammi et al., 2003). Furthermore, in 

diabetic rats, the methanolic whole plant extract of Vinca rosea at a dose of 500 mg/kg BW 

showed considerable antihyperglycemic effect as well as improvements in body weight, lipid 

profile and pancreatic β-cell regeneration. Some β-cells might have survived after alloxan's 

action, allowing Vinca rosea extract to act on them and causing to generate insulin, resulting in 

the plant's antidiabetic function. Furthermore, histological tests revealed that Vinca rosea extracts 

repair the pancreas, proving its antihyperglycemic activity. Antidiabetic efficacy of Ravenala 

madagascariensis leaf revealed the n-Hexane, ethyl acetate, ethanol and water leaf extracts of this 

plant at a concentration of 50 g/l showed antidiabetic property in both at in vitro and in vivo 

system at different levels. The ethanolic and water extracts strongly inhibited the impact on 

glucose diffusion in vitro and both extracts showed considerable in vivo antidiabetic property; 

moreover, the ethanolic extract exhibited superior blood glucose reducing property than the water 

extract. As a result, the findings proved the utilization of this plant as traditional medicine to cure 

diabetes (Priyadarsini et al., 2010). 

            The water extract of Garcinia kola seeds, when given orally at a concentration of 200 

mg/kg BW to normal rats, it was able to considerably reduce (p˂0.05) blood glucode levels, as 

well as efficiently boost (p˂0.05) superoxide dismutase action. The catalase activity, on the other 

hand, was not significantly affected (p>0.05). As a result, the study demonstrated that Garcinia 

kola, which has long been used in Nigeria to optimise neurological alertness and sleeplessness, 

may also have hypoglycemic and antioxidative potentials (Omage et al., 2011). The antioxidant 

action and in vitro alpha-amylase property of Amaranthus spinosus in alloxan-induced diabetic 

rats was evaluated. Amaranthus spinosus has commonly been utilized to treat a variety of 

illnesses (Vaidyaratanam, 1996; William D'ymock, 1976; Kirtikar and Basu, 1987). The findings 

revealed that the methanolic extract of Amaranthus spinosus could considerably suppress the α-

amylase activity, lower the increased blood sugar levels, reduce malondialdehyde and recover 

glutathione and catalase levels, which might be related to the active compound(s) found in the 

plant extract. An experiment of the anti-diabetic potential of Scoparia dulcis in STZ-induced 

diabetes rat was conducted. The water extract of Scoparia dulcis at a concentration of 250 mg/kg 

BW/twice in daily basis resulted in a significant reduction in fasting blood sugar level, urine 

sugar, thiobarbituric acid reactive substances, reduced glutathione and glycogen level with a 

simultaneous gain in body weight (Das and Chakraborty, 2011). 

In addition to in vivo antidiabetic study, an in vitro experiment based on inhibitory effect 

on enzymatic activity can be useful in understanding the mechanism of plant extracts in the 

treatment of diabetes (Kifle et al., 2022). As a result, reduction of α-amylase and α-glucosidase 

has received a lot of attention since it may offer an approach to regulate blood sugar levels in type 



24 
 

2 diabetes people (Ali et al., 2006). In this regard, the anti-hyperglycemic effect of Caesalpinia 

digyna root methanolic extract was investigated for in vitro α-amylase and α-glucosidase 

inhibitory activity. The extract reduced both α-amylase and α-glucosidase activity in varying 

degrees (Narkhade et al., 2011). The flavanols found in the extract are thought to be responsible 

for the plant's α-amylase inhibitory property, whereas the α-glucosidase inhibitory action is 

related to the intestinal α-glucosidase inhibitory activity. As increased blood sugar level following 

meal is one of the most prominent characteristics of diabetes mellitus, pharmacological efforts 

aimed at reducing postprandial hyperglycemia by suppressing the action of α-amylase have been a 

primary focus in diabetes management. The leaf of Thespesia populnea was evaluated for in vitro 

α-amylase inhibitory action (Sangeetha and Vedasree, 2012). The findings revealed that all of the 

extracts utilized, including petroleum ether, chloroform, ethyl acetate and methanol, had different 

levels of α-amylase inhibitory action. Ethyl acetate and methanol fraction, on the other hand, 

showed significant inhibitory action while compared with other extracts. Additional research 

revealed that the inhibitors have proteinous structure. Overall, the research supports the folkoric 

usage of Thespesia populnea to lower oxidative stress and ameliorate postprandial 

hyperglycemia, hence assisting in the prevention of diabetic complications. 

            In a study the reducing impact of Telfaira occidentalis on α-amylase and α-glucosidase 

was analyzed and it was found that both unprocessed and blanched Telfaira occidentalis leaf 

extracts showed enzymatic inhibition at varying degrees, with unprocessed leaf extracts showing 

greater inhibition. The antioxidant potential of Telfaira occidentalis leaf, together with enzyme 

inhibitory action, could be a plausible explanation for its application in the treatment of type 2 

diabetes (Oboh et al., (2012). The different leaf extracts of Carica papaya L., such as ethyl 

acetate, alcohol and water extract raised the percentage inhibitory effect on α-amylase in varying 

degrees while also slowing the digestion of starch over time. The method by which Carica 

papaya exhibited its inhibitory function could be linked to its effect on carbohydrate binding 

domain of α-amylase leading to the break down of the internal α-1, 4 glucosidase links in starch, 

thus inhibiting postprandial hyperglycemia (Jiju et al., 2013). 

                Cassia fistula Linn., has been commonly used to treat hematemesis, pruritus, intestinal 

problems, leucoderma, diabetes and as an antipyretic, analgesic and laxative (Bhakta et al., 2001). 

Shrikant and Manjunath, (2013) have backed up the traditional assertion that Cassia fistula can 

help with diabetic treatment. They investigated the in vitro α-amylase inhibitory actions of the 

entire alcoholic bark fraction of Cassia fistula, as well as its ethyl acetate and butanol extracts. 

The ethyl acetate fraction showed the most substantial inhibitory effect. The existance of 

flavonoids in the ethyl acetate extract could be the cause of α-amylase inhibitory activity.  

              In vitro α-amylase and α-glucosidase inhibitory property of Terminalia bellirica bark 

were investigated by Mary and Gayathri, (2014). Its extracts in petroleum ether, chloroform and 

ethanol showed different degrees of α-amylase and glucosidase inhibition. However, the ethanolic 

fraction displayed significant inhibitory action, which could be related to the existence of 

additional metabolites in the sample. The in vitro α-amylase activity of petroleum ether, 



25 
 

chloroform, ethyl acetate and methanol fractions of Tinospora cordifolia leaf was also reported by 

Shareef et al., (2014). The ethyl acetate and methanol extracts possessed the most significant 

inhibitory efficacy. Both in vivo and in vitro antihyperglycemic potential of Actinidia kolomikta 

extracts was evaluated by Yuan et al., (2014). Alcohol and aqueous extracts of both the root and 

leaf of this plant showed α-glucosidase inhibitory effect at varying levels. Moreover, water leaf 

extract inhibited α-glucosidase more effectively when compared with the other extracts. 

Additionally, the water extract was found to lower blood glucose levels without producing 

hypoglycemia, as well as control severel diabetes-related blood parameters like protein 

metabolism, lipid profile and liver functions, indicating that Actinidia kolomikta could be a viable 

and long-term resource for diabetes treatment. The methanolic bark extract of Pseudovaria 

macrophylla at doses of 200 and 400 mg/kg BW were able of reducing blood sugar levels in STZ-

nicotinamide induced diabetic rats, as well as efficiently raising antioxidant enzymes, decreased 

glutathione, progressing serum insulin, C-peptide levels and reducing lipid peroxidation levels 

(Aditya et al., 2014). Moreover, Pseudovaria macrophylla significantly decreased serum pro-

inflammatory cytokines while efficiently restoring the shape of the islet and β-cells. Furthermore, 

increased expression of insulin protein, GLUT-1, GLUT-2 and GLUT-4 in pancreatic cells could 

be one of the pathways behind the plant extract's antihyperglycemic effect. 

              Folk remedies for diabetes treatment have been widely utilized around the world until 

date. Although advancements in diabetes management, rural and urban African communities still 

depend entirely on folk medicines. Severel Sudanese plants have been documented to have 

antidiabetic property. In this regard, the antidiabetic potential of Mitragyna inremis, Nauclea 

latifolia, Randia nilotica, Tinospora bakis and Striga hermonthica has been investigated. The 

experiment revealed that water extracts of Tinospora bakis, Nauclea latifolia and Randia nilotica 

at concentrations of 400 mg/kg BW could efficiently decrease blood sugar levels in diabetic rats 

at acute condition. Additionally, the plants water extracts exhibited a various potentiality to 

efficiently reduce total cholesterol, total triglycerides, LDL-Cholesterol, plasma SGOT, SGPT, 

urea and blood urea nitrogen, whereas enhance HDL-Cholesterol. Though, Striga hermonthica 

contained no antihyperglycemic effect on diabetic rats. As a result, the study backs up the 

utilization of these plants in Sudanese folk remedy (Maha et al., 2015). The ethanolic leaf extract 

of Phyllanthus amarus was found to decrease blood glucose levels in alloxan-induced diabetic 

mice effectly (Shetti and Kaliwel, 2015). In another research, Gupta et al., (2015) evaluated the 

antidiabetic activity of Urginea indica ethanolic bulb extract and they found that 1.5 g/kg BW 

dose when given orally, it efficiently decreased blood glucose, total cholesterol and triglyceride 

levels, while increase in HDL-cholesterol level in STZ-induced diabetic rats. 

            Antioxidant and α-glucosidase inhibitor screening of Merremia peltata was conducted by 

Af-idah et al., (2021) revealed significant DPPH and total antioxidant activity in its stem 

methanolic extract. Additionally leaf and stem extract of Merremia peltata showed potential as α-

glucosidase inhibitors for diabetic therapy. Dabie et al., (2022) evaluated the α-amylase inhibitory 

property of Anthocleista nobilis leaf extract. The 70% ethanolic extract had significant α-amylase 



26 
 

inhibitory property due to the presence of phytochemicals such as flavonoids, saponins, alkaloids, 

tannins and terpenoids.  Phytochemical investigation revealed the presence of three compounds 

namely, α-spinasterol, palmitic acid and pheophorbide A-methyl esters were isolated from wild 

Amaranthus cruentus and these were tested for in vitro antidiabetic activity.  Amaranthus extracts 

and isolated compounds showed strong α-glucosidase activity inhibition and mild α-amylase 

activity inhibition indicating that the compounds slow glucose absorption (Nkobole et al., 2021). 

Phytochemical investigation of the methanol stem-bark extract of Ficus capensis revealed the 

presence of alkaloids, cardiac glycosides, flavonoids, saponins, tannins, steroids, phenols and 

triterpenes. Its effects on alloxan induced hyperglycaemia in wistar rats reported that its fractions 

at tested doses (100, 200 and 400 mg/kg BW) significantly decreased blood glucose level after 2, 

4, 8, 16 and 24 h post administration when compared with diabetic control (Bashir et al., 2020). 

Different solvents like boiling water, 50% ethanol and 100% dan ethanol were used to extract 

Cosmos caudatus (kenikir) leaf and it was repoted that 50% ethanol extract had highest phenolic, 

flavonoid content and significantly higher antioxidant and antidiabetic property than other solvent 

fractions (Firdaus et al., 2021). Phytochemical screening of the Salvia officinalis leaf extracts 

revealed presence of flavanone, sterols, saponins, tannins, alkaloids and triterpenes. Aqueous leaf 

extract of Salvia officinalis showed significant hypoglycemic effect on alloxan-induced diabetic 

Swiss albino mice model while comparing with other extract like methanol, hexane and ethyl 

acetate (Mbiti et al., 2020). Anti-diabetic activity of Hylocereus polyrhizus (red dragon fruit peel) 

ethanolic extract against diabetic rats reported that 74.88 mg/200 g BW dose had statistically 

similar antidiabetic effect when compared with standard drug glibenclamide (0.09 mg/200 mg 

BW dose) (Panjaitan et al., 2021). In the Fokoue and Santchou subdivisions of the Menoua 

Division, West Cameroon and a total of 49 medicinal plant species representing 26 distinct 

botanical families were counted. For the treatment of diabetes, hypertension and cardiovascular 

diseases, plant species like Allium sativum, Aloe vera, Asystasia sp., Cymbopogon citratus, 

Gouania sp., Persea americana, Sonchus oleraceus and Vernonia amygdalina were thought to be 

quite helpful (Zhang et al., 2022). 

1.3.5. Effect of antidiabetic compounds isolated from plants 

‘Berberine’ is an oral hypoglycemic compound isolated from Coptis chinensis, Berberis 

amurense, Phellodendron amurense and various other plants having anti-dyslipidemic and anti-

obesity property. Several animal models have been used for extensive research on its metabolic 

activity in controlling blood glucose and lipids. Berberine is an AMP-activated protein kinase 

(AMPK) activator. Its insulin-independent hypoglycemia impact is linked to mitochondrial 

function inhibition, glycolysis promotion and AMPK pathway activation. Additionally, berberine 

might function as an inhibitor of α-glucosidase. This compound increases insulin sensitivity in 

newly diagnosed type 2 diabetic individuals, which lowers blood insulin levels. However, it may 

enhance insulin secretion in patients with impaired β-cell function by regenerating damaged islets 

(Yin et al., 2012).  



27 
 

       ‘Ellagic acid’ extracted from Emblica officinalis having many therapeutic benefits. Treatment 

with ellagic acid for 16 weeks after diabetes onset dramatically reduced renal impairment and 

oxidative stress. It greatly reduced the activation of NF-κB in the kidneys and also dramatically 

reduced renal disease and reduced the expressions of fibronectin and transforming growth factor-

beta in renal tissues. Interleukin-1 beta, IL-6 and tumour necrosis factor-alpha, three pro-

inflammatory cytokines were all considerably lowered in serum by ellagic acid. In diabetic rats, 

this compound had a protective impact on the kidneys in part due to its ability to lower blood 

sugar levels. This effect was accompanied by a reduction in inflammatory responses through 

inhibiting the NF-κB pathway (Ahad et al., 2014).  

           ‘Erianin’ is a naturally occurring substance isolated from Dendrobium chrysotoxum Lindl., 

which prevented choroid-retinal endothelial RF/6A cells from migrating and forming tubes as a 

consequence of high glucose. In RF/6A and microglia BV-2 cells, erianin decreased high glucose-

induced vascular endothelial growth factor (VEGF) production, hypoxia-inducible factor 1-alpha 

(HIF-1-alpha) translocation into nucleus and ERK1/2 activation. It also prevented VEGF-induced 

activation of VEGF receptor 2 (VEGFR2) and its downstream cRaf-MEK1/2-ERK1/2 and PI3K-

AKT signaling pathways in RF/6A cells, as well as VEGF-induced angiogenesis in both vitro and 

in vivo. In addition, this compound decreased the enlarged retinal arteries, VEGF expression and 

microglia activation in mice with oxygen-induced retinopathy and STZ-induced hyperglycemia 

(Yu et al., 2016).  

          ‘Resveratrol’ is a phytoestrogen compound having many beneficial influences on diabetic 

organisms. When administered to hyperglycemic mice, resveratrol lowered blood sugar levels. 

This effect appeared to be primarily the result of enhanced intracellular glucose transport. This 

compound had also been shown to protect Islets beta cells in diabetis. The potential of resveratrol 

to lower insulin secretion was revealed in tests on pancreatic islets; this effect was confirmed in 

animals with hyperinsulinemia, where it lowered blood insulin levels. Additionally, this 

compound had recently been found to block cytokine function and minimize the oxidative 

damage to pancreatic tissue. Resveratrol may also enhanced insulin activity, according to studies 

on animals with insulin resistance. It enhanced insulin action through a variety of mechanisms, 

including decreased adiposity, altered gene expression and altered enzyme activity. These 

findings suggested that this compound may help to manage and prevent diabetes (Szkudelski and 

Szkudelska, 2011). 

         ‘Piceatannol’ is a natural resveratrol-like analog that extracted from the seeds of the passion 

fruit (Passiflora edulis). The activation of sirtuin and AMP-activated protein kinase by resveratrol 

has led to speculation that it may be a substance that prevents metabolic disorders. Researchers 

examined the impact of piceatannol on mice that fed a high-fat diet. Their findings demonstrated 

that piceatannol had no impact on the body weight gain or visceral fat gain brought on by high-fat 

diets in mice; however it lowered fasting blood sugar levels. Model mice showed lower blood 

sugar levels after receiving a single dose of this compound. Thus it may be useful in the 

prevention of diabetes, according to the evidence (Uchida-Maruki et al., 2015).