Hepatoprotective effects of Nigella sativa seed extract against acetaminophen-induced oxidative stress

Objective: To investigate the protective effects of Nigella sativa seed extract (NSSE) against acetaminophen (APAP)-induced hepatotoxicity in TIB-73 cells and rats. Methods: Toxicity in TIB-73 cells was induced with 10 μmol/L APAP and the protective effects of NSSE were evaluated at 25, 50, 75, 100 μg/mL. For in vivo examination, a total of 30 rats were equally divided into five experimental groups; normal control (vehicle), APAP (800 mg/kg body weight single IP injection) as a hepatotoxic control, and three APAP and NS pretreated (2 weeks) groups (APAP + NSSE 100 mg; APAP + NSSE 300 mg and APAP + NSSE 900 mg/kg). Results: TIB-73 cell viability was drastically decreased by (49.0 ± 1.9)% after the 10 μmol/LAPAP treatment, which also increased reactive oxygen species production. Co-treatment with NSSE at 25, 50, 75, and 100 μg/mL significantly improved cell viability and suppressed reactive oxygen species generation. In vivo, the APAP induced alterations in blood lactate levels, pH, anionic gap, and ion levels (HCO₃^-, Mg²⁺ and K⁺), which tended to normalize with the NSSE pretreatment. The NSSE also significantly decreased elevated serum levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase induced by APAP, which correlated with decreased levels of hepatic lipid peroxidation (malondialdehyde), increased superoxide dismutase levels, and reduced glutathione concentrations. Improved hepatic histology was also found in the treatment groups other than APAP group. Conclusions: The in vitro and in vivo findings of this study demonstrated that the NSSE has protective effects against APAP-induced hepatotoxicity and metabolic disturbances by improving antioxidant activities and suppressing both lipid peroxidation and ROS generation.