丁香苦苷解离常数及油水分配系数的测定

目的:测定丁香苦苷解离常数和油水分配系数。方法:采用紫外分光光度法,测得丁香苦苷解离常数,应用HPLC测定丁香苦苷的表观正辛醇/水分配系数。结果:丁香苦苷解离常数pKa为9.628 4±0.14。油水分配系数Papp为1.206 9(logPapp=0.0817),当pH 4.5,5.5,6.5,7.5,8.5时,油水分配系数Papp分别为1.388 1,1.352 9,1.335 8,1.370 4,1.133 3,表明丁香苦苷的表观正辛醇/缓冲溶液分配系数受缓冲溶液pH的影响不大。结论:在生理pH下,丁香苦苷大部分以未解离的分子状态存在,但丁香苦苷水溶性好,脂溶性较差,可能会对丁香苦苷的吸收分布及设计药物剂型产生影响。

Determination of Dissociation Constants and Apparent Oil/Water Partition Coefficient of Syringopicroside

Objective: To determine the dissociation constants of syringopicroside and its partition coefficients for the n-octanol-water/buffer solution systems. Method: To determine the dissociation constants of syringopicroside were determined by UV-visible spectrophotometer, at the same time, the partition coefficients in the n-octanol-water /buffer solution systems of syringopicroside were determined by shaking flask method. Result: The pka value is 9. 628 4±0. 14, and the n-octanol/water partition coefficient P_app is 1. 206 9 (logP_app=0. 081 7). When the pH is 4. 5, 5. 5, 6. 5, 7. 5, 8. 5, the n-octanol/water partition coefficient P_app is 1. 388 1, 1. 352 9, 1. 335 8, 1. 370 4, 1. 133 3 respectively, indicating that there is little effect on the n-octanol/water partition coefficient of syringopicroside in different pH values buffer solution. Conclusion: In the physiological environment, drugs most existed as most molecular state. The syringopicroside has good hydrophilicity, but poor liposolubility, it maybe affect the absorption, distribution of syringopicroside and the design of dosage forms.