Solanum nigrum L. extract inhibits 2-acetylaminofluorene-induced hepatocarcinogenesis through overexpression of glutathione S-transferase and antioxidant enzymes.

Solanum nigrum L. (SN) is a widespread plant and is regarded as a common relish in the east and the south of Taiwan. Our previous study has found that SN water extract (SNWE) alleviated carbon tetrachloride-induced liver damage in rats. However, the effects of SNWE on chemical-induced hepatic injury and hepatocarcinogenesis remain unclear. Therefore, this study aims to investigate the effects of SNWE on hepatic injury and hepatocarcinogenesis by using 2-acetylaminofluorene (AAF) and AAF/NaNO(2) treatment. The serum biomarkers for hepatic injury, glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, and gamma-glutamyl transferase, and for hepatocarcinogenesis, alpha-fetoprotein, were determined. Our results showed that AAF treatment led to a significant decrease of body weight and an increase of liver/body weight and serum biomarkers for hepatic injury and hepatocarcinogenesis. Interestingly, the SNWE supplement significantly lowered the liver/body weight and the biomarkers but did not affect the body weight. Further investigation revealed that a SNWE supplement increased the expression of glutathione S-transferase-alpha and -mu, the level of transcription factor for protection from oxidative stress, Nrf2, and the level of downstream targets regulated by Nrf2, including glutathione peroxidase, superoxide dismutase-1, and catalase. Moreover, the effects of SNWE on AAF/NaNO(2)-induced hepatoma were also investigated, and the findings revealed that SNWE suppressed the progression of the hepatoma and resulted in a great increase of the survival rate. Our findings indicate that the SNWE supplement significantly alleviated the AAF-induced hepatic injury and early hepatocarcinogenesis as well as the AAF/NaNO(2)-induced lethal hepatoma, which may result from the overexpression of glutathione S-transferases, Nrf2, and antioxidant enzymes.