OBJECTIVETo determine the O/W partition coefficient of panax pseudo-ginseng saponin (PNS) and investigate the absortion kinetics of it in whole small intestine and different intestinal segments of rats.

METHODThe shake-flask method was employed to determine the O/W partition co-efficient of geniposide, and an in situ intestinal perfusion model was employed to investigate the absorptive kinetics of geniposide.

RESULTThe partition coefficient (P) of R1, Rg1 and Rb, of PNS were 1.0814, 6.3104 and 0.2743, respectively, and their logP were 0.0340, 0.8001, -0.5618, the absorptive rate constants (Ka) of R1, Rg1 and Rb1 of PNS at the concentration of 0.2, 0.5, 1.0 g x L(-1) were (0.135 +/- 0.006), (0.110 +/- 0.002), (0.095 +/- 0.016), (0.144 +/- 0.015), (0.110 +/- 0.006), (0.099 +/- 0.011), (0.238 +/- 0.013), (0.140 +/- 0.008), (0.137 +/- 0.012)h(-1), respectively. The Kb of R1, Rg1 and Rb1 of PNS were (0.030 +/- 0.006), (0.033 +/- 0.004), (0.033 +/- 0.007), (0.032 +/- 0.006), (0.044 +/- 0.012), (0.044 +/- 0.011), (0.042 +/- 0.007), (0.065 +/- 0.007), (0.044 +/- 0.014)h(-1) at duodenum, jejunum, ileum, respectively. The absorption rate of Rb1 was higher than R1 and Rg1.

CONCLUSIONAccording to the P and the logP, it can be conjectured that the absorption of R1 and Rg1 are better than Rb1. The absorption rate is decreased with the increase of the PNS concentration. Their absorption is the passive diffusion mechanism and other transport may also take part in the transport process. PNS is absorbed at all small-intestinal segments of rats, there are no significant differences between the three sections.