Elucidation of the antioxidant and antimicrobial activity of extracts of leaves of Neptunia prostrata Linn

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The herb Neptunia prostrata Linn. which belongs to Mimosaceae family has been used in folkloric medicine in the North-eastern states of India, Assam and Tripura by indigenous herbal healers since time immemorial but there is a scarcity of any background study documenting its use as an antimicrobial herb. This unmet need led to the present study being conceptualised with the objective to evaluate any antioxidant property and antimicrobial activity of the leaf extracts of this herb in the selected strains of bacteria. For the same, plants were collected and authenticated. Following identification of these herbs, methanolic, ethanolic, pet ether and chloroform extracts were prepared using soxhletion. Acute toxicity study as per OECD guidelines 420 was assessed in wistar albino rats and in swiss albino mice (n=5) of both sexes at doses of 2000 mg/kg body weight and did not reveal any morbidity or mortality in the animals within the stipulated period. Phytochemical screening was performed on all four extracts of Neptunia prostrata. Phytochemical constituents depicted the presence of glycoside, and flavonoids in only ethanolic, methanolic and chloroform extracts. Alkaloids were present in the chloroform extract. The antimicrobial activity was performed by disc agar diffusion method with respect to amoxicillin at standard doses against ATCC strains of Gram positive Staphylococcus aureus, Bacillus subtilis and Gram negative Salmonella typhi. The herbs showed antioxidant activity comparable to standard antioxidants in-vitro such as Ascorbic acid (Vitamn C) with comparable IC 50 values. The results of the antibacterial assay on the basis of the zone of inhibition (mm) and MIC values of the extracts of (NPHE) under study suggest these two indigenous herb have conspicuous and potent putative role in the therapeutics of a vast plethora bacterial infections that need to be corroborated for the expansion of future prospective in-vivo studies with larger sample size