Hepatoprotective effects and mechanisms of l‐theanine and epigallocatechin gallate combined intervention in alcoholic fatty liver rats

BACKGROUND Chronic excessive alcohol consumption can lead to alcoholic fatty liver, posing substantial health risks. l‐Theanine (LTA) and epigallocatechin gallate (EGCG) in tea exert antioxidant and hepatoprotective effects. However, the combined effects of LTA and EGCG on rats with alcoholic fatty liver, and the underlying mechanisms of such effects, remain unclear. In this study, Sprague Dawley (SD) rats were fed with alcohol for 6 weeks to induce alcoholic fatty liver. Subsequently, for another 6 weeks, the rats were administered LTA (200 mg kg−1 day−1), EGCG (200 mg kg−1 day−1), or a combination of LTA with EGCG (40 mg kg−1 day−1 l‐Thea +160 mg kg−1 day−1 EGCG), respectively. RESULTS The combined use of LTA and EGCG for alcoholic fatty liver disease had more significant effects than their individual administration. This combination reduced the activity of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as the levels of hepatic triglyceride (TG), malondialdehyde (MDA), and reactive oxygen species (ROS) in the rats. The combined intervention also increased hepatic superoxide dismutase (SOD) and glutathione peroxidase activity. Reductions in hepatic fat accumulation and inflammatory responses were observed. The mechanism underlying these effects primarily involved the inhibition of fatty acid synthesis and the alleviation of lipid peroxidation through the downregulation of the mRNA and protein expression of TNF‐α, SREBP1c, and CYP2E1 and the upregulation of the mRNA and protein expression of ADH1, ALDH2, Lipin‐1, PPARαPPARα, AMPK, and PGC‐1α, thereby promoting the oxidative decomposition of fatty acids and reducing the synthesis of cholesterol and glucose. CONCLUSION l‐Theanine and EGCG appear to be able to alleviate alcoholic fatty liver by modulating lipid metabolism and ameliorating oxidative stress, indicating their potential as natural active ingredients in anti‐alcoholic fatty liver food products. © 2024 Society of Chemical Industry.