酶水解百分之五十罗汉果皂苷Ⅴ方法学研究

Methodology of enzymic hydrolysis of fifty percent mogroside Ⅴ

罗汉果是我国常用的一种中药,用于治疗干咳、口腔溃疡及便秘等,罗汉果皂苷是罗汉果果实中的主要药效物质,为一类葫芦烷三萜皂苷类化合物。由于个别罗汉果低糖皂苷在罗汉果中含量较低,因而难以对这些皂苷有效地进一步进行代谢或药理等研究。该研究采用RP-HPLC监测50%罗汉果皂苷V的水解过程,并对其水解条件进行正交实验优化其组合,建立了酶水解50%罗汉果皂苷V以获取罗汉果次级皂苷的方法。结果表明:酶水解50%罗汉果皂苷V获得罗汉果皂苷ⅢE、Ⅲ、ⅣE和赛门苷I等次级皂苷的最佳水解条件是p H值为5.6的乙酸-乙酸钠缓冲体系,反应温度为55℃,β-葡聚糖酶活性浓度为40万U·L-1,罗汉果皂苷V的反应浓度为0.2 g·L-1,水解时间为10 h。经多次验证,该水解条件重现性好,可用于从50%罗汉果皂苷V中水解制备罗汉果皂苷ⅢE、Ⅲ、ⅣE和赛门苷I等罗汉果皂苷。该研究结果为进一步水解其他罗汉果次级皂苷提供了依据。

Luo Han Guo,the dried fruits of Siraitia grosvenorii,is a kind of traditional Chinese medicine and used for the treatment of dry cough,sore throat,and constipation etc. Previous chemical investigations revealed that the major valid compounds of S. grosvenorii were mogrosides,belonging to cucurbitane-type triterpenes. Due to the fact that some mogrosides are low content in S. grosvenorii,it is hard to achieve enough amount of these compounds to further study their metabolism and pharmacology etc. So a methodology was established in this paper to obtain enough mogrosides of low content（ such as mogroside ⅢE,Ⅲ,ⅣE,and siamenoside I） by enzymic hydrolysis of 50% mogroside Ⅴ. The hydrolysis was monitored by RP-HPLC and orthogonal experiments was applied to optimize the reaction conditions. The experiment result indicated the optimal reaction conditions were： in p H 5. 6 acetic acid-sodium acetate buffer solution,reaction temperature was 55 ℃,β-dextranase concentration was 400 k U·L-1,reaction concentration of mogroside Ⅴ was 0. 2 g·L-1,reaction time was 10 h. It had been verified that the method was repeatable,which could be applied to hydrolyze 50% mogroside Ⅴ to obtain mogroside ⅢE,Ⅲ,ⅣE,and siamenoside Ⅰ. This result also could be a guide for hydrolyzing others secondary-mogrosides.