天然低共熔溶剂提取水飞蓟宾工艺优化及基于COSMO-SAC机理探讨

Optimization of Silybin Extraction Using Natural Deep Eutectic Solvents and Mechanism Discussion Based on COSMO-SAC

水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后的水飞蓟种壳粉为原料,用初步筛选所得较优NADES,即:氯化胆碱+1,4-丁二醇进行提取,HPLC法测定水飞蓟宾含量,在单因素实验基础上,采用响应面法对该NADES提取水飞蓟宾工艺进行优化。结果表明:料液比1:20 g/mL,提取温度77.0℃、时间5.6 h,模型预测水飞蓟宾得率可达4.29%,与实验值4.30%基本一致。基于片段活度系数类导体屏蔽模型(Conductor-like Screening Model for Segment Activity Coefficient,COSMO-SAC),分别对水飞蓟宾和溶剂分子(NADES与传统溶剂乙醇)进行结构与能量优化,通过量子化学计算,得到水飞蓟宾在两种溶剂中的无限稀释活度系数的对数分别为-6.922和-6.043,分子间相互作用能分别为-51.62和-25.47 kJ/mol,以探讨不同溶剂提取水飞蓟宾效果差异机理。

As a bioactive component extracted from the seed of milk thistle,silymarin has many pharmacological functions,such as liver-protective and cholagogic effect.It is categorized as a class of flavonoids,among which silybin is one of the main components.Efficient extraction of silybin with a type of new and green solvent natural deep eutectic solvent(NADES),as well as mechanism discussion were explored in this study.With the degreased milk thistle seed shell powder as raw material and using HPLC for silybin analysis,NADES composed of choline chloride/1,4-butanediol was screened out as optimal solvent for silybin extraction.On the basis of single factor experiments,Box-Behnken Design from response surface methodology was used for process optimization.The generated model predicated that the highest silybin yield of4.29% would be achieved with solid-liquid ratio of 1:20 g/mL,at 77℃ for 5.6 h.The result from verification experiment was about 4.30%,which fitted well with the prediction.Then,based on conductor-like screening model for segment activity coefficient(COSMO-SAC),structure and energy optimization of silybin and solvent were attempted.The logarithms of infinite dilution activity coefficients in the two solvents,chloride/1,4-butanediol and the traditional organic solvent ethanol,were-6.922 and -6.043,and the intermolecular interaction energies were -51.62 and -25.47 kJ/mol,respectively,which would provide insight into the mechanism explaining performance difference of the solvents during extraction.