荆芥内酯平衡溶解度和油水分配系数的测定

Determination of equilibrium solubility and apparent oil/water partition coefficient of schizonepetin

目的:测定荆芥内酯的平衡溶解度和在正辛醇-水/缓冲液体系中的表观油水分配系数。方法:采用HPLC法测定荆芥内酯在水和各种有机溶剂中的平衡溶解度;采用摇瓶法测定荆芥内酯在正辛醇-水/缓冲液体系中的表观油水分配系数。结果:25℃时荆芥内酯在水中的平衡溶解度为910 mg.L-1,常用有机溶剂甲醇对荆芥内酯的溶解性较好,为93 855 mg.L-1;25℃时荆芥内酯的正辛醇-水的表观分配系数为49.35(lnKow=1.69)。结论:荆芥内酯在石油醚中几乎不溶,在水中的平衡溶解度较低,在甲醇中的平衡溶解度较高,在酸性至中性磷酸盐缓冲溶液中的表观分配系数变化不大,碱性条件下的表观分配系数明显下降。

Objective： To determine the equilibrium solubility of schizonepetin and its partition coefficients in the n-octanol-water/buffer solution systems.Method： The HPLC method was established and used to detect the concentration of schizonepetin in water and different organic solvents;the partition coefficients in the n-octanol-water/buffer solution systems of schizonepetin were determined by shaking flask method.Result： The equilibrium solubility of schizonepetin was 910 mg·L-1 in water at 25 ℃.A higher equilibrium solubility of schizonepetin was reached at 93 855 mg·L-1 in methanol.Partition coefficients in the n-octanol-water/buffer solution systems of schizonepetin was 49.35（lnKow=1.69）at 25 ℃.Conclusion： Schizonepetin was almost insoluble in petroleum ether.It has a low solubility in water balance.Equilibrium solubility in methanol is higher than what in other solvents.It have little change in apparent distribution coefficient in neutral phosphate buffer solution and has significant decrease in apparent distribution coefficient under the alkaline conditions.