Objective:To study on the absorption characteristics of polydatin and resveratrol from Polygoni Cuspidati Rhizoma et Radix extract in the stomach and small intestine of rats. Method:In situ single pass intestinal perfusion model in rats was adopted

taking contents of polydatin and resveratrol as indexes

HPLC was employed to determine contents of polydatin and resveratrol before and after being perfused Polygoni Cuspidati Rhizoma et Radix extract for investigating their absorption characteristics in the stomach and small intestine of rats. Result:The absorption rate of Polygoni Cuspidati Rhizoma et Radix extract was proportional to drug concentration in the stomach.Absorption rate of polydatin in Polygoni Cuspidati Rhizoma et Radix extract with low dose showed significant difference(P<0.05) when compared with the middle and high dose groups

but there was no significant difference between the middle dose group and the high dose group.The absorption rates of resveratrol at different dose groups indicated significant deviation by SPSS 17.0(F=609.724

P<0.05).When the dose of Polygoni Cuspidati Rhizoma et Radix extract was 600 mg·L-1

the absorption rate constants (Ka) of polydatin and resveratrol were 0.925

0.575 h-1

respectively.The Ka and absorption rates of polydatin and resveratrol in different dose groups were not significantly different. Conclusion:Polydatin in Polygoni Cuspidati Rhizoma et Radix extract has a concentration saturation phenomenon in the stomach

its mechanism may be an active absorption or facilitated diffusion;while the absorption rate of resveratrol in the stomach increased with the increase of extract concentration

this suggests that the resveratrol might be absorbed in the stomach via passive transport mechanism.Different concentrations of Polygoni Cuspidati Rhizoma et Radix extract had no effect on the intestinal absorption of polydatin and resveratrol

and absorption is not saturated

this suggests that polydatin and resveratrol may be absorbed in intestine via passive diffusion mechanism.