Tea is a famous beverage that is produced from leaves of Camellia sinensis. Amongst the six major tea categories in China, dark tea is the only one that involves microbial fermentation in the manufacturing process, which contributes unique flavors and functions for the tea. In the recent decade, the reports about the biofunctions of dark teas have increased rapidly. Therefore it may be the proper time to consider dark tea as one potential homology of medicine and food. In this viewpoint, our current understanding of the chemical constituents, biological activities and possible health beneficial effects of dark teas were introduced. Some future directions and challenges to the development perspectives of dark teas were also discussed. 相似文献
Four unknown stilbenoids, including one dimer, namely 4′-methoxy-scirpusin A (5) and three monomeric stilbene glycosides, namely piceatannol-3′-O-[2′′-(3,5-dihydroxy-4-methoxybenzoyl)]-β-d-glucopyranoside (13), piceatannol-3′-O-(2′′-galloyl)-β-d-glucopyranoside (14) and piceatannol-3′-O-(6″-p-coumaroyl)-β-d-glucopyranoside (16) together with 15 described compounds, were isolated from the ethyl acetate fraction of the ethanol extract of roots of Rheum lhasaense based on the guidance of the inhibitory effect on acetylcholinesterase. The structures of the unknown compounds were established by combined spectroscopic analysis and comparing their spectral data with compounds with similar structures. Some selected components were also investigated for their inhibitory abilities on acetylcholinesterase (AChE), indicating that compound 13 may be responsible for higher inhibitory activity of the ethyl acetate fraction on AChE.