Antioxidant activity of seed extracts of Annona squamosa and Carica papaya.

摘要

Various extracts of seeds from custard apple or papaya were characterized in terms of antioxidative activity, free radical scavenging ability, total phenols content and total flavonoids content. Seeds were subject to microwave-assisted extraction using hexane, acetone, chloroform/methanol (2:1), 50% ethanol or water as extraction solvent, and the resultant extracts were analysed for antioxidative properties and polyphenols content, a potential correlation between these parameters was also investigated. Results show that the highest antioxidative activity (3179.66 g gallic acid equiv./g dry extract) and phenols content was measured for the chloroform/methanol extract of papaya seeds. Max. radical scavenging activity (3201.63 g ascorbic acid equiv./100 g of dry extract) was exerted by the aqueous custard apple seeds extract, whereas the acetone extract of papaya seeds had the highest flavonoids content among all the extracts produced. Polar extracts were better free radical scavengers compared with less polar ones. Hexane extracts showed least DPPH radical scavenging activity. Acetone proved efficient in extracting flavonoids, whereas phenols were best extracted using the mixture of chloroform and methanol. Phenols seemed to contribute significantly towards the antioxidative activity of the papaya seed extracts, but less so towards that of the custard apple seeds extracts.