采用制备色谱技术,通过甲基化技术得到的甲基化儿茶素粗品中,分离纯化出3个甲基化表没食子儿茶素没食子酸酯(EGCG)的单体,结合LC/MS和NMR等分别确定为4',4″-di-Me-EGCG、4',3″,4″-tri-Me-EGCG以及4',3″,4″,5″-tetra-Me-EGCG;进一步比较了这3个EGCG甲基衍生物单体与98%EGCG在清除DPPH自由基活性和总抗氧化活性等方面的差异。结果表明:EGCG甲基化后清除DPPH自由基活性和总抗氧化活性都有明显的降低,总体上分别只有98%EGCG的68.17%和6.84%。
Three methylated EGCG derivatives were purified by preparative chromatography,and their structures were identified by LC/MS and NMR as the following: 4′,4″-di-Me-EGCG、4′,3″,4″-tri-Me-EGCG and 4′,3″,4″,5″-tetra-Me-EGCG.DPPH scavenging assay and the evaluation of total antioxidant activity experiment showed that the methylated EGCG derivatives had much lower antioxidant capability than 98% EGCG,only to 68.17% and 6.84% of 98% EGCG in average,respectively.
