西藏红景天主要成分在萃取体系中的分配行为

红景天甙和酪醇是西藏红景天的主要成分,在溶剂萃取体系中的分配行为尚不清楚。采用不同的溶剂萃取体系研究了西藏红景天浸提液中红景天甙和酪醇的分离效果,考察了预处理、pH值、萃取剂等条件对分配行为的影响。结果表明,浸提液经除鞣质预处理后可以降低萃取过程乳化现象;液-液两相萃取中,在pH值<9.0时,磷酸三丁酯(TBP)作为萃取剂时红景天甙和酪醇在有机相中质量分数分别可达60%和98%以上,下相可获得较纯的红景天甙溶液;采用TBP-聚乙二醇(PEG2000)-硫酸铵三相萃取体系,当pH值>10.0时,红景天甙主要分配于中间相和下相中,中间相约占70%,而酪醇主要分配在上相,约占65%以上,下相中质量分数低于5%。

Partition behaviors of main ingredients in Rhodiola Tibetica in solvent extraction systems

Salidroside and p-tyrosol are the main active ingredients. Their partition behaviors are not clear in different solvent extraction systems. Separation of salidroside and p-tyrosol from Rhodiola Tibetica extract was investigated in different solvent extraction systems. Effect of extraction conditions such as pretreatment, pH and extractants on partition behaviors was also studied. Results showed that pretreatment of tannins removal from the extract can avoid emulsification during solvent extraction. For liquid-liquid solvent extraction, mass fraction of salidroside and p-tyrosol in tributyl phosphate (TBP) phase can reach 60% and 98%, respectively when pH is below 9.0. Purified salidroside solution can be obtained in the lower aqueous phase. For the three-liquid-phase system composed of TBP, PEG2000 and ammonium sulphate, salidroside is mainly partitioned into the middle phase and the top phase, 70% of salidroside in the middle phase. p-tyrosol is mainly partitioned into the top phase, above 65%, but its mass fraction in the bottom phase is below 5% .