Antioxidant activities of pomegranate fruit extract and its anthocyanidins: delphinidin, cyanidin, and pelargonidin

Antioxidant activities of freeze-dried preparations of a 70% acetone extract of pomegranate (Punica granatum L.) and its three major anthocyanidins (delphinidin, cyanidin, and pelargonidin) were evaluated. Free radical scavenging activities were examined using an ESR technique with spin trapping; DMPO for hydroxyl (.OH) and superoxide (O-2(.-)) radicals; and [(MGD)(2)Fe2+] for nitric oxide (NO). Inhibitory effects on lipid peroxidation were estimated by the levels of malonaldehyde and 4-hydroxyalkenals in rat brain homogenates. Pomegranate extract exhibited scavenging activity against .OH and O-2(.-). Anthocyanidins inhibited a Fenton reagent .OH generating system possibly by chelating with ferrous ion. Anthocyanidins scavenged O-2(.-) in a dose-dependent manner. The ID50 values of delphinidin, cyanidin, and pelargonidin were 2.4, 22, and 456 muM, respectively. In contrast, anthocyanidins did not effectively scavenge NO. Anthocyanidins inhibited H2O2-induced lipid peroxidation in the rat brain homogenates. The ID50 values of delphinidin, cyanidin, and pelargonidin for them were 0.7, 3.5, and 85 muM, respectively. These findings suggest that the above anthocyanidins contribute to the antioxidant activity of pomegranate fruits.