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以表没食子儿茶素没食子酸酯(EGCG)为原料,用硫酸二甲酯对其进行部分甲基化。甲基化产物经乙酸乙酯萃取,再经硅胶柱、凝胶柱和反相硅胶柱分离得到EGCG的甲基化衍生物,再经ESI-MS,MS/MS和1HNMR鉴定。利用高效液相色谱技术测定分离到的甲基化EGCG和EGCG在人工模拟体胃液与肠液中的变化。结果表明,该体系合成甲基化EGCG的最佳条件是:硫酸二甲基酯与EGCG的摩尔比1∶1,在60℃水浴条件下回流反应5h。通过分离,最后得到纯度为93.86%的单甲基化产物242 mg,得率约为9%,经鉴定其结构为EGCG4″Me。在人工模拟胃液中,EGCG4″Me脱去甲基,生成EGCG,起到缓释作用;而在人工模拟肠液中,EGCG4″Me由于甲基化,稳定性提高。
Epigallocatechin gallate (EGCG) was used as a starting material and partially methylated with dimethyl sulfate. The methylated product was extracted with ethyl acetate and the methylated derivatives of EGCG were isolated by silica gel column, gel column and reverse phase silica gel column, and identified by ESI-MS, MS / MS and 1HNMR. The changes of the isolated methylated EGCG and EGCG in gastric and intestinal juice of artificial simulants were determined by HPLC. The results showed that the optimal conditions for the synthesis of methylated EGCG were as follows: the molar ratio of dimethyl sulfate to EGCG was 1: 1, and refluxed at 60 ℃ for 5 h. Through the separation, the final result was a monomethylated product with 93.86% purity, 242 mg with a yield of about 9%, which was identified as EGCG4 “Me. In artificial gastric juice, EGCG4” Me demethylated to form EGCG , Play a role in sustained release; and artificial simulated intestinal fluid, EGCG4 "Me due to methylation, increased stability.