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l-Theanine Inhibits (−)-Epigallocatechin-3-gallate Oxidation via Chelating Copper
Journal of Agricultural and Food Chemistry ( IF 5.7 ) Pub Date : 2022-06-13 , DOI: 10.1021/acs.jafc.2c01379
Lijie Jia 1 , Fuming Wang 1 , Ke Zhang 1 , Dongxu Wang 1 , Xiaoxiao Wang 1 , Xiuli Li 1 , Jinsong Zhang 1
Affiliation  

Our recent study showed that glutamate can inhibit dopamine oxidation via chelating copper. l-Theanine is an amino acid analogue of glutamate, whereas tea (−)-epigallocatechin-3-gallate (EGCG) is similar to dopamine in avidly undergoing oxidation. We thus hypothesized that l-theanine could also restrain EGCG oxidation via chelating copper. The current study scrutinized influences of l-theanine on EGCG oxidation in vitro and in vivo. The in vitro results showed that l-theanine and copper formed an l-theanine–copper complex with impaired redox activity of copper. Accordingly, l-theanine effectively suppressed copper-facilitated EGCG oxidation, hydroxyl radical production, and DNA damage; inhibited EGCG autoxidation which in essence involves catalysis of transition metals such as copper; and reduced EGCG oxidation-associated formation of a quinone adduct with proteins known as quinoproteins. Consistently, l-theanine significantly increased hepatic EGCG levels and reduced hepatic quinoprotein levels and liver injury in mice treated with EGCG. These lines of evidence together suggest that tea l-theanine can protect against tea catechin oxidation.

中文翻译:

l-茶氨酸通过螯合铜抑制 (−)-Epigallocatechin-3-gallate 氧化

我们最近的研究表明,谷氨酸可以通过螯合铜来抑制多巴胺的氧化。l-茶氨酸是谷氨酸的氨基酸类似物,而茶 (-)-表没食子儿茶素-3-没食子酸酯 (EGCG) 与多巴胺相似,都在剧烈氧化。因此,我们假设l-茶氨酸也可以通过螯合铜来抑制 EGCG 氧化。目前的研究仔细研究了l-茶氨酸对体外和体内 EGCG 氧化的影响。体外结果表明,l-茶氨酸和铜形成了l-茶氨酸-铜络合物,铜的氧化还原活性受损。因此,l-茶氨酸有效抑制铜促进的EGCG氧化、羟基自由基的产生和DNA损伤;抑制 EGCG 自氧化,其本质上涉及铜等过渡金属的催化;并减少 EGCG 氧化相关的醌加合物与称为醌蛋白的蛋白质的形成。一致地,在用 EGCG 治疗的小鼠中,l-茶氨酸显着增加了肝脏 EGCG 水平并降低了肝脏醌蛋白水平和肝损伤。这些证据线一起表明茶l-茶氨酸可以防止茶儿茶素氧化。
更新日期:2022-06-13
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