Cellular damage arising from free radicals is one of the fundamental mechanisms underlying a number of human neurodegenerative disorders like diabetes, inß ammation, Alzheimers disease, autoimmune pathologies, and digestive system disorders. Thus, antioxidants play an important role in the treatment of such diseases. Natural sources of antioxidants, free of carcinogenicity unlike synthetic ones, are being tapped for antioxidant formulations. The present study aims at a comparative evaluation of hexane, alcoholic, and aqueous extracts of fresh lemon peel for antioxidant activity. All extracts were subjected to phenolic content estimation by the Folin-Ciocalteau method and ß avonoid content estimation by the aluminium chloride colorimetric method. Results revealed that the alcoholic extract had the maximaml content of both phenolics and ß avanoids. Antioxidant activity was evaluated by using the beta-carotene bleaching method, the nitric oxide radical scavenging and the hydrogen peroxide scavenging assays. The alcoholic extract was found to have good free radical inhibitory property as well as nitric oxide radical scavenging activity. The hexane extract, however, showed only good hydrogen peroxide scavenging activity. Thus, the higher antioxidant activity of the alcoholic and hexane extracts of Citrus limon peel could have wide therapeutic utility against various diseases.
Key words: Antioxidant activity, Citrus limon, ß avonoids, phenolics.