Evaluating Antioxidant and Antimicrobial Activities of Phenolic Essences Extracted from Evening Primrose (Oenothera biennis) Flowers

Evening primrose (Oenothera biennis) is a biennial flowering plant increasingly cultivated for medicinal use of γ-linolenic acid rich oil of its seeds. In this study, total phenolic and flavonoids content, antioxidant and antimicrobial activity of aceton, ethanolic and metanolic extracts of evening primrose flowers were evaluated. Aceton extract had the highest extraction yield, total phenol and flavonoids content. Extracts were also tested for their antioxidant activity using scavenging activity of 2,2- diphenyl-1-picrylhydrazyl and reducing power of Fe+3 in comparision with BHT. BHT was the highest in DPPH radical scavenging and reducing power followed by aceton, ethanolic and methanolic extracts. The extracts also showed good antibacterial activity against all of tested microorganism and the tested gram-negative bacteria was more resistant to inhibitory effect of extracts. Among different bacteria tested, Salmonella. typhimurium was found to be the most resistant to aceton and ethanolic extracts. The MBC values, with respect to aceton and ethanolic extracts for Salmonella. typhimurium were 10 and 20 (μg/ml), respectively.