Diverse antioxidants protect against acetaminophen hepatotoxicity

The reactive oxygen species-sensitive transcription nuclear factor-kappaB (NF-kappaB) plays a pivotal role in the development of acetaminophen (APAP) hepatotoxicity. We investigated the efficacy of a diverse series of antioxidants in preventing APAP-induced hepatotoxicity. BALB/c mice were divided into four groups and provided with antioxidants incorporated into chow as follows: (1) control diet; or diet supplemented with (2) S-adenosylmethionine (SAMe); (3) green tea polyphenols (GrTP); or (4) (RS)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA). After 5 days on these diets, the animals were further subdivided into (A) given an IP injection with APAP (750 mg/kg), or (B) kept as untreated controls. The animals were sacrificed at 0, 4 h, and 24 h following APAP administration. PAP/vehicle induced marked decreases in hepatic reduced glutathione (GSH) levels and endogenous SAMe concentrations (46%) when compared to controls. APAP also caused severe centrilobular necrosis and marked increase in serum enzyme ALT activity (38-fold). Oral administration of antioxidants significantly attenuated the APAP-induced liver damage and depletion of hepatic GSH. There were profound increases in serum TNF-alpha levels at 4 h following APAP administration in nonsupplemented compared to antioxidant-treated animals, but no significant differences noted after 24 h. Serum amyloid A increased in APAP-challenged mice irrespective of antioxidant treatment. Finally, hepatic SAMe concentrations were drastically decreased 24 h following APAP administration, and these decreases were attenuated by pretreatment with antioxidants. In conclusion, these orally administered antioxidants with dissimilar properties provided protection against liver damage, supporting the potential use of antioxidant therapy in patients with APAP toxicity. This is the first report that GrTP and oral administration of PTCA and SAMe can provide protection against APAP injury in this model.