Activity of polyphenolic plant extracts as scavengers of free radicals and inhibitors of xanthine oxidase

ABSTRACT

The free radical scavenging activity of ethanolic and aqueous extracts from six plants has been evaluated, in vitro, using 1, 1-diphenyl-2-picrylhydrazyl [DPPH] radical scavenging method and compared with ascorbic acid, quercetin. kaempferol and apigenin. Extracts of Pistacia integerrima leaves and galls exhibited highest DPPH radical scavenging activity among all the plants extracts examined. Carissa carandas from Apocynaceae and Vitex negundo of Verbenaceae family also demonstrated DPPH radical scavenging activity. Inhibitory effects towards the in-vitro reaction of hypoxanthine and xanthine oxidase [XO] was also carried out in the presence of plant extract, aglycones quercetin, kaempferol and apigenin along with allopurinol The extracts from Pistacia integerrima galls exhibited highest XO inhibitory activity than leaves of Pistacia integerrima and other plant extracts, was comparable with aglycones but less than allopurniol, a pharmacologically different structure. The increased DPPH radical scavenging and XO inhibitors activity by Pistacia integerrima galls may be partly exerted by flavonoids produced during stress of an insect aphids [Pemphogus species] attack on the leaves. The results indicate that Pistacia integerrima may be a good candidate for future studies in vivo models of gout and hyperuricemia