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

Molecules

Gerold Jerz¹  Peter Winterhalter¹  Maria Ramos-Jerz¹  Dongchao Xie²  Jiakun Peng²  Weidong Dai²  Zhi Lin² 

[1] Institute of Food Chemistry, Technische Universität Braunschweig, Schleinitzstrasse 20, 38106 Braunschweig, Germany;Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, 9 Meiling South Road, Hangzhou 310008, China;

关键词: white tea;    Camellia sinensis;    N-ethyl-2-pyrrolidinone-substituted flavanols;    epimer isolation;    centrifugal partition chromatography;    biphasic solvent system evaluation;   

DOI  :  10.3390/molecules26237284

来源: DOAJ

【 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′′′R- and 5′′′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 α, 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 α-glucosidase with IC₅₀ of 70.3 and 161.7 μM, respectively.

【 授权许可】

Unknown