积雪草苷平衡溶解度和油水分配系数的测定

目的测定积雪草苷在不同pH介质中的平衡溶解度和正辛醇-水/缓冲液体系中的表观油水分配系数（Papp）。方法采用RP-HPLC法测定积雪草苷浓度,研究其在水和不同pH介质中的平衡溶解度;采用摇瓶法测定积雪草苷在正辛醇-水/缓冲液体系中的Papp。结果 25℃下积雪草苷在水中的平衡溶解度为305.02μg.ml-1,在pH 5.0缓冲液中平衡溶解度更低;积雪草苷在正辛醇-水中Papp为0.908（logPapp=-0.042）,在pH 5.0缓冲液中Papp最高。结论积雪草苷为亲水性药物,但其在水中的溶解度较小。在pH 5.0～8.0范围内,积雪草苷的平衡溶解度随pH的增加而增加,相反油水分配系数随pH的增加而减少。

Determination of Equilibrium Solubility and Apparent Oil/Water Partition Coefficient of Asiaticoside

Objective To determine the equilibrium solubility of asiaticoside and its apparent partition coef- ficient in n-octanol-water/buffer solution systems. Methods An HPLC method was used to determine the concentra- tion of asiaticoside in water and phosphate buffer solutions while the partition coefficient for the n-octanol-water/ buffer solution systems of asiaticoside was determined by shaking flask method. Results The equilibrium solubility of asiaticoside in water was 305.02 μg · ml- 1 at 25 ℃ and exhibited a lower solubility of 307. 347 μg ·ml- 1 at pH 5.0. The partition coefficient of asiaticoside was 0. 908 in the n-octanol-water system and the maximum partition co- efficient was in the n-octanol-buffer solution system at pH ty and hydrophilic property. The equilibrium solubility of Conclusion Asiaticoside is a drug with little solubili- asiaticoside increases with pH within the range of 5.0 -8.0, but the apparent partition coefficient is the opposite. 5.0.