Antioxidant activity of extracts from Alpinia katsumadai seed.

Alpinia katsumadai (Zingiberaceae) has been widely used in traditional Chinese medicine to treat a variety of conditions such as emesis and gastric disorders. However, very little is known about the cellular actions by which this plant mediates its therapeutic effects. Various aspects of antioxidant activity were evaluated in a total extract derived from Alpinia katsumadai seed in this study. Relatively high levels of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity were detected in the total extract (IC(50) 1.6 microgram/mL). Other known compounds such as (-)-epigallocatechine-3-gallate (EGCG) and resveratrol showed IC(50) values of <0.8 and 4.8 microgram/mL, respectively. The total extract also enhanced the viability of Chinese hamster lung fibroblast (V79-4) cells and inhibited H(2)O(2)-induced apoptosis. The total extract of Alpinia katsumadai also dose-dependently enhanced the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in V79-4 cells, and these effects were comparable to other antioxidant compounds such as EGCG and resveratrol. Taken together, our findings show that Alpinia katsumadai contains significant antioxidant activity.