State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China.
State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China.
Food Chem. 2014;152:539-45. doi: 10.1016/j.foodchem.2013.10.117. Epub 2013 Nov 1.
Phytochemical investigation of the aqueous extract of pu-erh tea afforded eight novel 8-C N-ethyl-2-pyrrolidinone substituted flavan-3-ols (puerins I-VIII) by (1)H, (13)C, two-dimensional nuclear magnetic resonance (NMR) and high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS) analysis. Comparative chemical analysis of green tea, black tea and Chinese dark teas confirmed that these compounds were the marker compounds of Chinese dark teas. Furthermore, fungal fermentation was indispensable for the biosynthesis of these novel compounds. Through single fungal fermentation, it was proved that catechins and theanine were the precursors of puerins I-VIII. HPLC-DAD-ESI/MS analysis elucidated the biosynthetic pathway for puerins I-VIII. Puerins I-IV have potential protective effects for the human micro-vascular endothelial cells (HMEC) injury induced by hydrogen dioxide compared to other tea polyphenols. 8-C N-ethyl-2-pyrrolidinone substituted flavan-3-ols could be used in the quality control and authentication of Chinese dark teas.
植物化学研究表明，普洱茶的水提物通过（1）H、（13）C、二维核磁共振（NMR）和高效液相色谱-二极管阵列检测-电喷雾电离质谱联用（HPLC-DAD-ESI/MS）分析，得到了八种新型的 8-C N-乙基-2-吡咯烷酮取代的黄烷-3-醇（puerins I-VIII）。通过对绿茶、红茶和黑茶的比较化学分析，证实这些化合物是黑茶的特征化合物。此外，真菌发酵对于这些新型化合物的生物合成是必不可少的。通过单一真菌发酵，证明儿茶素和茶氨酸是 puerins I-VIII 的前体。HPLC-DAD-ESI/MS 分析阐明了 puerins I-VIII 的生物合成途径。与其他茶多酚相比，puerins I-IV 对过氧化氢诱导的人微血管内皮细胞（HMEC）损伤具有潜在的保护作用。8-C N-乙基-2-吡咯烷酮取代的黄烷-3-醇可用于黑茶的质量控制和鉴定。
