Flavonoids from Alpinia vietnamica, and their cytotoxic, antioxidative, and α-glucosidase inhibitory activities

Phytochemical research of the 80% EtOH whole plant extract of Alpinia vietnamica H.. Tran, Luu & Skornick resulted in the isolation and structural elucidation of seven compounds 1-7, including two flavones quercetin-3-O-alpha-l-rhamnosyl (1 -> 2)-alpha-l-rhamnoside (1) and diosmetin (2), three flavanones pinocembrin (3), alpinetin (4) and 5-O-methylnaringenin (5), and two chalcones cardamonin (6) and helichrysetin (7). The isolated compounds have shown biological effects at different levels. Two chalcones 6-7 showed cytotoxicity toward four cancer cell lines KB, MCF7, A549, and HepG2, especially compound 7 strongly inhibited the growth of A549 cancerous cells with the IC50 of 6.81 mu m. Flavone 1 strongly exhibited antioxidative activity to scavenge DPPH radicals with the IC50 of 51.68 mu m. Flavone 2 and flavanone 4 moderately inhibited enzyme alpha-glucosidase with the IC50 values of 296.34-324.64 mu m.