酶法制备葛根素的丙酯衍生物

Enzymatic Preparation of Puerarin Ester Derivatives

摘要:

本文研究了不同种类的水解酶催化非水相葛根素丙酰化反应的催化效率，并研究以Novozym 435脂肪酶催化葛根素丙酰化反应为模型，几个关键反应因素对该模型的影响规律。研究发现固定化脂肪酶Novozym 435、Lipozyme IMTL、Lipozyme IMRM均能高效催化葛根素丙酰化反应，且转化率高达98%以上，但另外几种游离脂肪酶催化葛根素丙酰化反应活性及效率就特别低。相同条件下，猪胰脂肪酶催化葛根素丙酰化反应的转化率为67%左右；胰脂肪酶和CRL脂肪酶表现很低的催化活性，肽酶和蛋白酶没有表现催化活性。以四氢呋喃为反应溶剂，2 mg/mL Novozym 435脂肪酶，底物：酰基供体之比为1:30，水分含量为0的反应条件下，反应6 h，底物转化率达到99.5%。反应产物经分离纯化后进行了结构鉴定，高效液相色谱、质谱、傅里叶红外光谱结果表明，非水相酶催化葛根素酰化反应主要生成单酯，所得产物酯为葛根素丙单酯，区域选择性达98%。

Abstract:

In this paper, the catalytic efficiency of different kinds of enzymes on the acylation reaction of puerarin was studied in non-aqueous phase. Among 8 kinds of enzymes, immobilized lipases Novozym 435, Lipozyme IMTL and Lipozyme IMRM could efficiently catalyze the acylation reaction of puerarin and conversion rate was as high as 98%, but the activity and efficiency of other free lipases catalyzed the acylation of puerarin were very low. Under the same conditions, the conversion rate of puerarin catalyzed by porcine lipase was about 67%, pancreatic lipase and CRL lipase showed low catalytic activity, and peptidase and protease did not exhibit catalytic activity. And Novozym 435 showed the highest catalytic activity. Using Novozym 435 as catalyst, the optimum reaction medium, dosage of lipase catalysts, mole ratio of substrates, initial water content and reaction time were determined as THF, 1:30, 2 mg/mL, 0 and 6 h, respectively. Under the above reaction conditions, conversion of puerarin reached 99.5%. The products were purified and structurally identified using HPLC, mass spectrometry (MS) and fourier transform infrared spectroscopy (FT-IR) which showed that the lipase catalyzed the acylation of puerarin, the resulting product was puerarin propionate monoester, where the regioselectivity reached 98%.