Protective Effect of Theanine on the Acetaminophen-induced Hepatotoxicity

The hepatoprotective effects of theanine on acetaminophen (APAP)-induced hepatotoxicity were investigated in vivo and in vitro. The effects of theanine on liver toxicity induced by APAP were assessed by blood biochemical and histopathological analyses. APAP treatment (400 mg/kg) caused severe liver injury in mice as indicated by their significantly elevated plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Pretreatment with theanine for 3 days attenuated the increase in ALT and AST when challenged with APAP. These protective effects of theanine against APAP-induced toxicity were consistent with the results from the histopathological examinations. We next examined the effects of theanine on the GSH concentration in liver plasma. The hepatic GSH level was significantly elevated in a dose-dependent manner by theanine treatment. The results suggest that the protective effects of theanine APAP-induced hapatotoxicity by antioxidative effect and GSH induction, implying that theanine should be considered a potential chemopreventive agent.