Title
Flavoalkaloids with Pyrrolidinone Ring from Chinese Ancient Cultivated Tea Xi-Gui
Author
Jian Cheng, Fei-Hua Wu, Pu Wang, Jia-Ping Ke, Xiao-Chun Wan, Ming-Hua Qiu, Guan-Hu Bao
Year
2018
Journal
Journal of Agricultural and Food Chemistry
Abstract
The Chinese Xi-Gui tea is one ancient cultivated variety of Camellia sinensis var. assamica. It has been used for producing expensive and elite tea in China presently. Five new flavoalkaloids, (−)-6-(5'''S)-N-ethyl-2-pyrrolidinone-epicatechin-3-O-gallate (ester-type catechins pyrrolidinone E, etc-pyrrolidinone E, 1), (−)-6-(5'''R)-N-ethyl-2-pyrrolidinone-epicatechin-3-O-gallate (etc-pyrrolidinone F，2) (−)-8-(5'''S)-N-ethyl-2-pyrrolidinone-epicatechin-3-O-gallate (etc-pyrrolidinone G, 3a), (−)-8-(5'''S)-N-ethyl-2-pyrrolidinone-catechin-3-O-gallate (etc-pyrrolidinone I, 4a), (−)-8-(5'''R)-N-ethyl-2-pyrrolidinone-catechin-3-O-gallate (etc-pyrrolidinone J, 4b), and one new naturally occurring natural product (−)-8-(5'''R)-N-ethyl-2-pyrrolidinone-epicatechin-3-O-gallate (etc-pyrrolidinone H，3b) together with the known flavoalkaloids etc-pyrrolidinones A−D (5, 6, 7a，7b ) were detected and isolated from Xi-Gui green tea. Their structures were identified by comprehensive NMR spectroscopic analyses. Absolute configurations of 1−3 were established by comparison of the CD analyses with epicatechin-3-O-gallate (ECG). Compounds 1−4 were evaluated for their protection against high glucose induced cell senescence on human umbilical vein endothelia cells (HUVECs) and showed significant protection effects (p < 0.01) at both 1.0 and 10 μM. Discussion on the possible evolution of tea plant divergent from related food plants on the basis of phytochemical view was also provided.
Instrument
J-810
Keywords
Circular dichroism, Absolute configuration, Natural products, Food science