积雪草苷平衡溶解度和油水分配系数的测定

摘要

Objective To determine the equilibrium solubility of asiaticoside and its apparent partition coefficient in n-octanol-water/buffer solution systems.Methods An HPLC method was used to determine the concentration 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 coefficient was in the n-octanol-buffer solution system at pH 5.0.Conclusion Asiaticoside is a drug with little solubility and hydrophilic property.The equilibrium solubility of asiaticoside increases with pH within the range of 5.0-8.0,but the apparent partition coefficient is the opposite.%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305.02 μg·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.