State Key Laboratory of Phytochemistry and Plant Resources of West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, People's Republic of China.
University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
J Agric Food Chem. 2020 Jul 29;68(30):7955-7963. doi: 10.1021/acs.jafc.0c02401. Epub 2020 Jul 14.
As a subgroup of flavoalkaloids, -ethyl-2-pyrrolidinone substituted flavan-3-ols are reported to possess various biological activities that may play important roles in the beneficial healthcare functions of tea. The HPLC and LC-MS analyses showed the existence of -ethyl-2-pyrrolidinone substituted flavan-3-ols in 'Jin-Ya', which is a Yunnan black tea produced only from the buds of the tea plant var. . Further phytochemical study on this precious black tea led to the identification of 8 flavoalkaloids, -, along with 11 known flavan-3-ols (-) and flavonol glycosides (-). The new compounds, (-)-6-(5″)--ethyl-2-pyrrolidinone-epiafzelechin (), (-)-8-(5″)--ethyl-2-pyrrolidinone-epiafzelechin-3--gallate (), and (-)-8-(5″)--ethyl-2-pyrrolidinone-epiafzelechin-3--gallate (), were identified based on extensive spectroscopic analysis. Flavoalkaloids - showed inhibitory activity on α-glucosidase with IC values ranging from 2.09 to 8.47 μM, compared to those of quercetin and acarbose (IC = 6.87 and 228.9 μM, respectively). Moreover, compounds , , and displayed an inhibitory effect on acetyl-cholinesterase with IC values of 14.23, 33.79, and 34.82 μM, respectively, compared to tacrine (IC = 0.223 μM).
作为黄烷酮类的一个亚组， -乙基-2-吡咯烷酮取代黄烷-3-醇被报道具有各种生物活性，这些活性可能在茶的有益保健功能中发挥重要作用。HPLC 和 LC-MS 分析表明，-乙基-2-吡咯烷酮取代黄烷-3-醇存在于云南黑茶“金芽”中，该茶仅由茶树变种的芽制成。对这种珍贵黑茶的进一步植物化学研究导致鉴定出 8 种黄烷酮类化合物， -，以及 11 种已知的黄烷-3-醇（-）和黄酮醇糖苷（-）。这些新化合物，(-)-6-(5″)-乙基-2-吡咯烷酮-表儿茶素（）、(-)-8-(5″)-乙基-2-吡咯烷酮-表儿茶素-3-O-没食子酸酯（）和(-)-8-(5″)-乙基-2-吡咯烷酮-表儿茶素-3-O-没食子酸酯（），是基于广泛的光谱分析鉴定的。黄烷酮类化合物 - 对 α-葡萄糖苷酶表现出抑制活性，IC 值范围为 2.09 至 8.47 μM，与槲皮素和阿卡波糖（IC = 6.87 和 228.9 μM）相比。此外，化合物 -、- 和 - 对乙酰胆碱酯酶表现出抑制作用，IC 值分别为 14.23、33.79 和 34.82 μM，与他克林（IC = 0.223 μM）相比。
