Postgraduate Department of Biochemistry, University of Medicine & Pharmacy "Carol Davila", Sos. Fundeni 258, Bucharest, Romania.
Molecules. 2012 Aug 29;17(9):10355-69. doi: 10.3390/molecules170910355.
Green tea extracts (GTEs) as well as their main component, the polyphenol epigallocatechin gallate (EGCG), are known for their versatile antioxidant, antimicrobial, antitumoral or anti-inflammatory effects. In spite of the huge beneficial action, there is increasing evidence that under certain conditions green tea and its components can be detrimental to living organisms. Using Saccharomyces cerevisiae strains with various defects in the response to oxidative stress, we found that GTEs or EGCG act in synergy with visible light, exhibiting either deleterious or protective effects depending on the solvent employed. Similar synergistic effects could be observed under singlet oxygen-generating conditions, such as light exposure in the presence of photosensitizers or UV-A irradiation, therefore solvent variance may represent a powerful tool to modulate the preparation of green tea extracts, depending on the intended target.
绿茶提取物（GTEs）及其主要成分，多酚表没食子儿茶素没食子酸酯（EGCG），以其多功能的抗氧化、抗菌、抗肿瘤或抗炎作用而闻名。尽管具有巨大的有益作用，但越来越多的证据表明，在某些条件下，绿茶及其成分可能对生物体有害。使用对氧化应激反应有各种缺陷的酿酒酵母菌株，我们发现 GTEs 或 EGCG 与可见光协同作用，根据所使用的溶剂，表现出有害或保护作用。在产生单线态氧的条件下，如在光增敏剂存在下暴露于光或 UV-A 照射下，也可以观察到类似的协同效应，因此溶剂差异可能是一种根据预期目标调节绿茶提取物制备的有力工具。
