Antimutagenic and α-glucosidase inhibitory effects of constituents from Kaempferia parviflora

The dichloromethane extract and ethyl acetate soluble fraction of Kaempferia parviflora showed antimutagenicity and α-glucosidase inhibitory activity. 7-Methoxyflavones were the major constituents of both extracts and demonstrated antimutagenic activity. In particular, 5,7-dimethoxyflavone (IC50 = 0.40 nmol/plate), 5,3′-dihydroxy-3,7,4′-trimethoxyflavone (0.40 nmol/plate), 3,5,7-trimethoxyflavone (0.42 nmol/plate) and 5-hydroxy-7-methoxyflavone (0.47 nmol/plate) showed potent antimutagenic activity. The results of structure–activity relationship studies suggest that methylation of the 5-hydroxy group enhanced activity. On the other hand, increasing the number of methoxy groups on the B ring caused a reduction in activity. In the case of an α-glucosidase inhibitory effect, 5,7,3′,4′-tetramethoxyflavone exhibited the highest activity (IC50 = 20.4 μM), followed by 5,7,4′-trimethoxyflavone (54.3 μM) and 3,5,7,3′,4′-pentamethoxyflavone (64.3 μM). The results suggest that the α-glucosidase inhibitory activity was enhanced by the methoxy groups at the 5-, 3′- and 4′-position and was reduced by the methoxy group at the 3-position.