脂质体电动色谱方法在定量保留活性关中的应用

【作者】 咸德玲；

【导师】 黄可龙；

【作者基本信息】 中南大学 ， 应用化学， 2008， 硕士

【摘要】 脂质体电动色谱是一种理想的评价药物与生物膜相互作用的模型。本文结合了脂质体电动色谱的简便、快速、自动化和微量等特点,从药物的脂水分配系数出发考察酸性药物阿魏酸和生物膜的相互作用。利用脂质体与生物膜结构的相似性,将脂质体加入毛细管电泳缓冲溶液中作为假固定相,在数分钟内测定了阿魏酸的脂水分配系数K_1w,建立了脂质体电动色谱评价阿魏酸与生物膜相互作用的方法。研究了脂质体中胆固醇的含量、缓冲溶液pH值和缓冲体系对K_1w的影响。结果表明,在实验条件范围内（胆固醇含量0%～30%,pH值4.00～12.00）,胆固醇的加入和缓冲溶液pH升高使K_1w降低,pH=7.0时,在三种缓冲体系中（硼酸盐、磷酸盐和Tris溶液）,离子强度越大,K_1w越高。在288 K～323 K范围内测定了中性芳香族溶质在脂质体电动色谱中的分配系数,通过三项式拟合Van’t Hoff图获得了一系列的热力学参数,研究了溶质在脂质体电动色谱中的热力学分配行为。结果表明,分配系数随体系温度的升高和苯环所带CH₂基团数目的增加而增大。从288 K到323 K,△H＞0,-T△S＜0,△G＜0,溶质在脂质体电动色谱中的分配过程为熵驱动过程。从288 K到298 K,脂质体电动色谱分配系统的△C_P为负值,其表现行为与经典疏水作用一致。从303 K到323K,脂质体电动色谱分配系统的△C_P为正值,其表现行为与经典疏水作用不完全吻合。△H和△S呈线性关系,该分配系统存在焓熵补偿。建立了脂质体电动色谱作为高通量筛选皮肤渗透性的体外分析方法。将脂质体电动色谱中保留因子的对数值（logk）作为自变量建立了定量保留活性关系式。采用SPSS分析软件对于16种结构不同的化合物进行分析,结果表明logk与皮肤渗透性常数线性相关性良好（r²=0.886）。采用交互验证评价了该模型的预测能力。在定量保留活性关系中的一个变量和传统定量构效关系中的三个变量可解释的能力（r²=0.704）相似。文中建立的定量保留活性关系模型对于新化合物早期的筛选可提供一种有效快捷的方法。建立了LEKC作为一种体外分析方法预测生物毒性的QRAR模型。从美国环境保护公司ECOTOX数据库中提取了15种芳香族化合物生物毒性参数(LC₅₀（鱼类,水蚤,糖虾）,EC₅₀（绿藻,水蚤）和ChV（鱼类和绿藻）)作为变量。拟和线性方程的r²值范围0.80～0.87,这说明LEKC的保留因子和毒性参数相关性良好。留一法交叉验证结果表明模型的预测能力良好,预测值与实验值较好吻合。脂质体电动色谱可用作芳香族化合物毒性的高通量筛选,为定量评估和预测同类其它化合物的生物毒性提供了参考依据。更多还原

【Abstract】 A facile method for evaluating acidic drug-biomembrane interaction was established by liposome electrokinetic chromatography（LEKC）. LEKC is a capillary electrophoresis technique where liposome is incorporated into a buffer solution and act as a pseudo-stationary phase using the structure similarity of liposome and biomembrane. Liposome-water partition coefficient(K_1w)of ferulic acid was determined in several minutes.The effect of cholesterol content,buffer pH and buffer composition on K_1wwas investigated respectively.An increase in cholesterol content（0%～30%）and pH values（4.00～12.00）resulted in a lower K_1w.In different buffer systems,the greater ionic strength was, the larger K_1wwas.The difference in K_1wrevealed ferulic acid-biomembrane interaction.LEKC is a good model evaluating the interaction of drug and biomembrane.Partition coefficients of neutral aromatic solutes in LEKC between 288 K～323 K were measured.A series of thermodynamic parameters were obtained by third-order polynomial fitting Van’t Hoff plots.The thermodynamic partitioning behavior for those solutes was investigated.The results showed that the partition coefficient became greater with the increasing of temperature and the number of CH₂ functional group in benzene.During the whole experiment temperature（288 K～323 K）,△H and T△S were positive while△G was negative,which indicated that the LEKC^- system of solutes partitioning into liposome was entropy-driven.From 288 K to 298 K,△C_P was negative and the LEKC partitioning system exhibited typical hydrophobic effect.From 303 K to 323 K,△C_P was positive and the LEKC partitioning system betrayed typical hydrophobic effect.A linear relationship between△H and△S indicated the occurrence of enthalpy-entropy compensation in LEKC system.LEKC provides a simple and facile approach for drug membrane interactions using liposome as a pseudostationary phase.This study evaluated the potential of LEKC for high-throughput skin permeability profiling as an in vitro technique.Quantitative retention-activity relationship（QRAR）model for the estimation of skin permeability was proposed.For the 16 structurally diverse chemicals,log k correlated well with permeability values（r²=0.886）.The predictive ability of the model was evaluated by cross-validation.The result was compared to traditional quantitative structure-activity relationship,QSAR,models using some molecular descriptors and physicochemical parameters.Interestingly,a single LEKC retention parameter was capable of describing the skin permeability,while three variables in QSAR were needed to achieve a similar correlation（r²=0.704）.The QRAR models developed in this paper may be a useful method to screening new chemicals and in the early stage of development and selection of chemicals.An investigation of the use of the retention in LEKC as an in vitro approach to predict the ecotoxicity is proposed.The ecotoxicity parameters(LC₅₀in fish,daphnia and mysid shrimp,EC₅₀in green algae and daphnia,and values of chronic ecotoxicity in fish and green algae)for 15 aromatic compounds were extracted from ECOTOX database from U.S.Environmental Protection Agency.QRAR models for the estimation of ecotoxicity were established.The r² of the fitted linear equations ranged from 0.80 to 0.87,which suggested good corralation between the retention in LEKC and the ecotoxicity parameters.The predictive ability of the models was evaluated by cross-validation.The results obtained indicated the usefulness of the LEKC systems investigated for the rapid ecotoxicity assessment of aromatic compounds.更多还原