Toxicological effects of green tea catechin extract on rat liver: Delineating safe and harmful doses

Abstract Purpose Catechins, the bioactive compounds found in green tea, are known for their beneficial health effects, but overconsumption may result in adverse effects. Thus, this study aimed to examine the influence of green tea ( Camellia sinensis L.) catechin extract (GTCE) on liver metabolism and structure in rats. Methods GTCE was phytochemically characterized by LC-MS spectrometry. An in vivo study was conducted on female rats separated into four groups of five each, i.e., a control group and three catechin-treated groups D1, D2, and D3 received, respectively, 0.4, 0.6, and 0.8 g/kg b.w./day of GTCE by gavage for 28 days. The effects of GTCE were monitored through the analysis of plasma lipid, oxidative stress markers, reduced glutathione (GSH) content, glutathione peroxidase (GPx) activity, and malondialdehyde (MDA) level in the liver. Furthermore, histopathological examinations of liver tissue were conducted. Results LC-MS analyses of GTCE revealed the presence of five phenolic compounds with a predominance of epigallocatechin-3-gallate (EGCG) at 60.1%. Exposure to catechins with an elevated dose (0.8 g/kg) caused oxidative damage in the liver, as indicated by a considerable increase ( p < 0.05) in MDA levels, a decrease in GSH content, and GPx activity ( p < 0.05), along with a decrease ( p < 0.05) in plasma total cholesterol, triglycerides, and total lipids in comparison to the control group. These changes were confirmed by histological examination. Conclusion Although catechins offer known health benefits, high doses may induce oxidative stress and liver damage.