Abstract

The present study was conducted to evaluate the antioxidant and antibacterial activities of methanol, acetone, chloroform and petroleum ether extracts of leaf, bark, pulp and seed of Seabuckthorn (Hippophae salicifolia D.Don) species found in Sikkim Himalayas. Antioxidant activity was measured using total phenolic content, reducing power and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The extraction yield and total phenolic contents were significantly higher in seed extracts with methanol being the most efficient solvent. Methanolic extract of seeds showed the highest reducing power and DPPH-radical scavenging activity among all the extracts.  Antibacterial activity was tested against six pathogenic strains viz. Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, Enterobacter aerogenes and Pseudomonas aeruginosa by agar diffusion and broth macrodilution methods. The extracts were found to exert low to strong antibacterial activity compared to a standard antibacterial agent. The results showed that seed and pulp extracts were better radical scavengers than leaf and bark extracts. Both antioxidant and antibacterial activities were found to be higher in methanolic extract. Strong correlation (P< 0.05) was observed between total phenolic content versus antioxidant and antibacterial activity from the extracts under study.

Keywords: Hippophae salicifolia, antioxidant activity, antibacterial activity, phenolic content, methanolic extract.