Potent SIRT1 enzyme-stimulating and anti-glycation activities of polymethoxyflavonoids from Kaempferia parviflora.

The SIRT1 enzyme-stimulating and anti-glycation activities of Kaempferia parviflora extract and its main polymethoxyflavonoids were evaluated in vitro. K. parviflora extract elevated SIRT1 catalytic activity by eight- and 17-fold at 20 μg/mL and 100 μg/mL, respectively, compared with vehicle only. Two major polymethoxyflavonoids, 3,5,7,3',4'-pentamethoxyflavone (4) and 5,7,4'-trimethoxyflavone (5), were isolated from this extract and are four- and fivefold more potent than resveratrol, hitherto the strongest known natural SIRT1 activator. In addition, the anti-glycation activity of K. parviflora extract was observed to be seven times more effective than aminoguanidine, a clinical anti-diabetes drug. 3,5,7,3',4'-Pentamethoxyflavone (4) and 5,7,4'-trimethoxyflavone (5) showed the strongest anti-glycation activity among the tested polymethoxyflavonoids. Further comparison of the activity of these structurally related polymethoxyflavonoids revealed a possible structure-activity relationship, in particular, for the contribution of methoxy moieties.