Evaluation of anti-bacterial potential and characterization of phytoconstituents of leaf extracts of Anisomeles indica (L.) Kuntze, a pharmacologically important herb from Terai-Duars region of West Bengal

Abstract

Medicinal plants have been a great source of herbal drugs, and with the advent of biotechnology, enormous novel herbal compounds have now been identified that may have a vast application in the pharmaceutical industry. Anisomeles indica (L.) Kuntze is an important medicinal plant found growing in the wild in the Terai Duars region of North Bengal, belonging to the family Lamiaceae. Although some of the studies have suggested the potential application of this plant extract for the treatment of bacterial diseases, none of the studies have studied the chemical composition of leaf extracts in great detail. In lieu of this, the present work has been framed to evaluate the phytochemical composition of leaf extracts of A. indica in two different solvents, i.e. ethyl acetate and ethanol, and the qualitative screening for the presence of various phytochemicals namely terpenoids, carbohydrates, steroids, flavonoids, alkaloids, phenols, tannins, cardiac glycosides, saponins, and lignins. Additionally, the antioxidant potential of ethanolic leaf extract was studied by analyzing DPPH activity and ABTS assay. The freehand sections of fresh A. indica leaves were carried out, and localization of the bioactive phytoconstituents inside the leaf was highlighted. One of the major approaches followed in this work was the evaluation of the antibacterial activity of leaf extracts, and it was found that ethanolic leaf extracts were highly effective against all tested bacterial strains (Bacillus subtilis ATCC 11774, Salmonella typhimurium ATCC 25241, Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 11229). Further, GC-MS profiling of the ethanolic extract confirmed the presence of a total of 15 compounds, of which 13 were found to be biologically active.