Antioxidant activity of\+i\Potentilla fruticosa.\-i

The molecular structures of the radical scavenging compounds present in extracts of Potentilla fruticosa blossoms were elucidated and the antioxidant activities of various extracts were determined. The activities of the different fractions were monitored by off-line and on-line RP-HPLC DPPH(super .) and ABTS(super .+) scavenging methods. Twelve compounds were isolated and identified, namely ellagic acid, catechin, quercetin-3-*b-glucopyranoside, quercetin-3-*b-galactopyranoside, quercetin-3-*b-rutinoside, quercetin-3-*b-glucuronopyranoside, quercetin-3-*a-arabinofuranoside, kaempferol-3-*b-rutinoside, kaempferol-3-O-*b-(6''-O-(E)-p-coumaroyl)glucopyranoside, rhamnetin-3-*b-glucopyranoside and rhamnetin-3-*b-galactopyranoside. The radical scavenging activity of each isolated compound was measured using DPPH(super .) and ABTS(super .+) assays and compared with the activity of rosmarinic acid. Catechin and ellagic acid were found to be the most active radical scavengers. The antioxidant properties of plant fractions were assessed in model systems by measuring superoxide anion and hydrogen peroxide scavenging, *b-carotene bleaching, hexanal production in edible oil, peroxide formation, and the increase in UV absorbance in the course of oxidation.