Abstract: 【Objective】 The purpose of this study was to explore the protective effect and mechanism of taraxasterol on oxidative damage of chicken primary hepatocytes induced by aflatoxin B₁ (AFB₁), and provide theoretical basis for the prevention and treatment of AFB₁ poisoning with taraxasterol.【Method】 Chicken primary hepatocytes were isolated by tissue block enzyme digestion and identified by PAS glycogen staining.The growth curve of hepatocytes was drawn by CCK-8 method.The toxicity of AFB₁ on hepatocytes was determined by MTT method,and the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the supernatant of hepatocytes were measured to determine the modeling concentration of AFB₁ in vitro.MTT method was used to find out the safe concentration of taraxasterol.The test was divided into 6 groups: Normal group,AFB₁ group,taraxasterol groups (high,medium and low doses) and Sil group.After the establishment of the primary hepatocyte injury model induced by AFB₁ and drug administration,the contents of reactive oxygen species (ROS) and malondialdehyde (MDA),superoxide dismutase (SOD) and glutathione (GSH) in the cells were determined by reagent kits.The expression of heme oxygenase-1 (HO-1),NADPH quinone oxidoreductase 1 (NQO1),Kelch like ECH associated protein 1 (Keap1),and nuclear factor E2 related factor 2 (Nrf2) of the key genes in Keap1/Nrf2 signal pathway were determined by Real-time quantitative PCR.【Result】 The cells were successfully isolated and identified as chicken primary hepatocytes. The cell viability was higher after 24-72 h culture; 0.05 μg/mL concentration was used as the modeling concentration of AFB₁ which induced primary hepatocyte injury in vitro; 20, 10 and 5 μg/mL concentrations were used as taraxasterol administration concentrations of the high, medium and low dose groups. Compared with AFB₁ group, taraxasterol could extremely significantly reduce the contents of ROS and MDA (P＜0.01), extremely significantly increase the activity of antioxidant SOD in AFB₁-induced chicken primary hepatocytes (P＜0.01), and extremely significantly or significantly increase the expression of HO-1, NQO1 and Nrf2 (except for 5 μg/mL taraxasterol) genes (P＜0.01 or P＜0.05), and reduce the expression of Keap1 gene in chicken primary hepatocytes induced by AFB₁. 【Conclusion】 Taraxasterol could improve the antioxidant capacity of chicken primary hepatocytes by regulating the Keap1/Nrf2 signal pathway,thus protecting against the oxidative damage of chicken primary hepatocytes induced by AFB₁.

Key words: aflatoxin B₁ (AFB₁); taraxasterol; chicken primary hepatocytes; oxidative stress; protective effect