Isolation of N-Ethyl-2-pyrrolidinone-Substituted Flavanols from White Tea Using Centrifugal Countercurrent Chromatography Off-Line ESI-MS Profiling and Semi-Preparative Liquid Chromatography

文献类型： 外文期刊

第一作者： Dai, Weidong

作者： Dai, Weidong;Xie, Dongchao;Peng, Jiakun;Lin, Zhi;Ramos-Jerz, Maria;Winterhalter, Peter;Jerz, Gerold

作者机构：

关键词： white tea; Camellia sinensis; N-ethyl-2-pyrrolidinone-substituted flavanols; epimer isolation; centrifugal partition chromatography; biphasic solvent system evaluation; off-line ESI-MS/MS metabolite profiling; semi-preparative liquid chromatography; inhibition; a; -glucosidase

期刊名称：MOLECULES （ 影响因子：4.927； 五年影响因子：5.11 ）

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年卷期： 2021 年 26 卷 23 期

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收录情况： SCI

摘要： N-Ethyl-2-pyrrolidinone-substituted flavanols (EPSF) are marker compounds for long-term stored white teas. However, due to their low contents and diasteromeric configuration, EPSF compounds are challenging to isolate. In this study, two representative epimeric EPSF compounds, 5 & PRIME;& PRIME;& PRIME;R- and 5 & PRIME;& PRIME;& PRIME;S-epigallocatechin gallate-8-C N-ethyl-2-pyrrolidinone (R-EGCG-cThea and S-EGCG-cThea), were isolated from white tea using centrifugal partition chromatography (CPC). Two different biphasic solvent systems composed of 1. N-hexane-ethyl acetate-methanol-water (1:5:1:5, v/v/v/v) and 2. N-hexane-ethyl acetate-acetonitrile-water (0.7:3.0:1.3:5.0, v/v/v/v) were used for independent pre-fractionation experiments; 500 mg in each separation of white tea ethyl acetate partition were fractionated. The suitability of the two solvent systems was pre-evaluated by electrospray mass-spectrometry (ESI-MS/MS) analysis for metabolite distribution and compared to the results of the CPC experimental data using specific metabolite partition ratio K-D values, selectivity factors alpha, and resolution factors R-S. After size-exclusion and semi-preparative reversed-phase liquid chromatography, 6.4 mg of R-EGCG-cThea and 2.9 mg of S-EGCG-cThea were recovered with purities over 95%. Further bioactivity evaluation showed that R- and S-EGCG-cThea possessed in vitro inhibition effects on alpha-glucosidase with IC50 of 70.3 and 161.7 mu M, respectively.

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