Phytochemical screening and antimicrobial activities of Periploca aphylla Decne, Persian walnut (Juglans regia L.) and oleander (Nerium indicum Mill.) Leaf extracts

Natural phenolic acids and their derivatives in plant extracts in addition to wide use in food industry, have also medicinal properties. In the present study, the antioxidant and antimicrobial activities of ethanol and water extracts of Periploca aphylla, Persian walnut and oleander leaves were evaluated using assays of 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, hydrogen peroxide scavenging activity and ferric-reducing capacity. In addition, total phenolic compounds, total flavonoids and anthocyanins content of the extracts were determined. The plants extracts showed different levels of antioxidant properties in various assays. The ethanol extracts, which have the highest amount of total phenolics and flavonoids, showed the highest antioxidant and antimicrobial activities in all assays, compared with water extracts. The extracts of P. aphylla were found to have the highest antioxidant potential, followed by Persian walnut and oleander extracts. The highest antimicrobial activity was found for both ethanol and aqueous extracts of P. aphylla, which showed the greatest effect on Gram-positive bacteria. The results suggest that the leaves of these plants specifically P. aphylla can be considered as a new source of natural antioxidant.