Acylated kaempferol glycosides from flower buds of Panax ginseng and their α-glucosidase inhibitory activity / 中草药

ABSTRACT

Objective: To study the chemical constituents of flavonoids and its α-glucosidase inhibitory activity from the flower buds of Panax ginseng. Methods The compounds were isolated and purified by MCI gel, silica gel and semi-preparative HPLC chromatography, and the structures were elucidated based on the NMR and MS data. The α-glucosidase inhibitory activities of the isolated compounds in vitro were determined by 96-well microtiter plate. Results: From ethyl acetate fraction of alcohol extract of P. ginseng flower buds, five flavonoids were isolated and identified as kaempferol-3-O-(2″,3″-di-E-p-coumaroyl)-α-L-rhamnoside (1), kaempferol-3-O-(3″,4″-di-E-p-coumaroyl)-α-L-rhamnoside (2), kaempferol-3-O-(3″-Z-p-coumaroyl,4″-E-p-coumaroyl)-α-L-rhamnoside (3), kaempferol-3-O-(2″,4″-di-E-p-coumaroyl)-α-L-rhamnoside (4), and kaempferol-3-O-(2″,4″-di-Z-p-coumaroyl)-α-L-rhamnoside (5). The inhibitory activity of α-glucosidase in vitro showed that compound 3 had stronger inhibitory effect on α-glucosidase. Conclusion: Compounds 1-5 are isolated from this genus for the first time, and the phenylpropionyl acylated flavonol glycosides in P. ginseng flower buds have some inhibitory effect on α-glucosidase in vitro.