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.Ð. Tran, Luu & Skornick resulted in the isolation and structural elucidation of seven compounds 1–7, including two flavones quercetin‐3‐O‐α‐l‐rhamnosyl (1→2)‐α‐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 µm. Flavone 1 strongly exhibited antioxidative activity to scavenge DPPH radicals with the IC50 of 51.68 µm. Flavone 2 and flavanone 4 moderately inhibited enzyme α‐glucosidase with the IC50 values of 296.34–324.64 µm.