Objective:To determine the apparent oil-water partition coefficient of oxysophocarpine in n-octanol-water and n-octanol-phosphate buffer system

and to provide reference for the absorption study in vivo. Method: The apparent oil-water partition coefficient for oxysophocarpine was performed by using shaking flask method with HPLC-DAD as separation and detection pathway. Result: The apparent oil-water partition coefficient of oxysophocarpine was log Papp=-0.44 in n-octanol-water system at 37 ℃. In pH 1.2-10.0 phosphate buffer solutions

log Papp was in the range of -0.97--0.25.When pH<4.5

there was no significant effect on it by pH. When pH>4.5

log Papp of oxysophocarpine showed the gradual increasing tendency with the increasing of pH. Conclusion: The methods described in the paper can be used to determine the oil-water partition coefficient of oxysophocarpine accurately

and help to predict the intracoporal process.