Evaluation of antimicrobial and antioxidant activities of Swertia petiolata

Abstract

Swertia petiolata is considered as an important medicinal herb and has been used to treat different ailments by various ethnic groups in Kashmir. The present study was designed to evaluate the antioxidant and antimicrobial activity of methanolic extract of S. petiolata. The antioxidant activity was evaluated by three different assays namely diphenylpicrylhydrazyl (DPPH), nitroblue tetrazolium (NBT) and ferric reducing power (FRAP). The IC 50 values of the methanolic extract were found to be 240 ± 4.14, 258 ± 5.71 and 100 ± 3.53 for DPPH, NBT and FRAP, respectively. The antimicrobial activities were determined by agar diffusion and microdilution methods against Gram-positive (Bacillus subtilis ATCC 6051, Sarcina lutea ATCC 10054, Staphylococcus aureus ATCC 25932), Gram-negative (Escherichia coli ATCC 25922, Enterobacter cloacae ATCC 13883, Pseudomonas aeruginosa ATCC 27853) and yeast (Candida albicans ATCC 10231). The methanolic extract was found to be more active against Gram-positive bacteria as compared to Gram-negative bacteria and the yeast. The Minimum inhibitory concentration (MIC) values ranged from 67.5-125, 125-250 and 350μg/ml for Gram-positive, Gram-negative and C. albicans respectively. Taken together, we propose that the plant is a rich source of antioxidants and antimicrobials.