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Author: search.filters.author.Saha, Jayati

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    In vitro antibacterial activity as related to antioxidant property of some ethnomedicinal plants
    (University of North Bengal, 2015-03) Saha, Jayati; Sarkar, Prabir Kumar
    The present study attempted to evaluate in vitro antibacterial and antioxidant activities of extracts from some ethnomedicinal herbs and to correlate among the parameters. The antibacterial activity was assayed using agar-disc diffusion method against seven bacterial species. Their total flavonoids content (TFC) and ferric reducing power (RP) were also evaluated. Herb extracts with high TFC exhibited a good antibacterial activity against the bacteria at low concentrations. The Gram-positive bacteria were more sensitive to the tested extracts than the Gram-negative ones. While Staphylococcus aureus was maximally inhibited, Escherichia coli was most resistant. Against each bacterium, antibacterial activity was positively correlated (r = 0.60-0.87) with TFC of the tested extracts. Positive correlations were also obtained between antibacterial and antioxidant activities (r = 0.60-0.96) as well as between TFC and antioxidant activity (r = 0.91) of the extracts. Thus, antibacterial and antioxidant activities of the tested extracts were closely associated with their flavonoid constituents.
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    ItemOpen Access
    Antioxidant and antimicrobial activities of a common liverwort from Darjeeling Himalaya
    (University of North Bengal, 2009-03) De, Rajib; Saha, Jayati; Sarkar, Prabir K
    The study was concerned with an examination of antioxidant and antimicrobial activities of methanolic extract of Marchantia convoluta (Merch.) L.. collected from Darjeeling Himalaya. The antioxidant activities were evaluated by means of five in vitro methods, viz. free radical-scavenging activity, Fe3+ -reducing power, metal-chelating ability, trolox equivalent antioxidant capacity (TEAC) and activity in hydroxyl radical-scavenging system. The total phenol content was 1.1 mg gallic acid equivalents g-1 dried thallus. After 30 min of reaction, the 100 mg lyophilized extract possessed 6.7 % free radical-scavenging activity. The same amount of extract exhibited 13.4 % 168.2 % metal-chelating and hydroxyl radical scavenging activities, respectively. The reducing activity was found to be 28.5 mg ascorbic acid equivalents g-1 dried thallus. Total antioxidant activity was 0.18 μg TEAC g-1 dried thallus. The antimicrobial activity was evaluated by testing the methanolic extract of the samples against five microorganisms including two Gram positive bacteria (Staphylococcus aureus and Bacillus cereus), two Gram negative bacteria (Escherichia coli and Klebsiella pneumoniae) and one yeast (Candida albicans by disc-diffusion assay. M. convoluta thallus extract was more or less inhibitory against all of the test bacteria, however did not possess any antifungal property. S. aureus was found to be most sensitive target organism.