African Nightshade ( Mill.): Impact of Cultivation and Plant Processing on Its Health Promoting Potential as Determined in a Human Liver Cell Model
Plant cultivation and processing may impact nutrient and phytochemical content of vegetables. The present study aimed at determining the influence of cultivation and processing on the health promoting capacity of African nightshade ( Mill.) leaves, an indigenous vegetable, rich in nutrients and phytochemicals. Anti-genotoxicity against the human liver carcinogen aflatoxin B1 (AFB₁) as determined by the comet assay and radical oxygen species (ROS) scavenging capacity of ethanolic and aqueous extracts were investigated in human derived liver (HepG2) cells. ROS scavenging activity was assessed using electron paramagnetic spin resonance and quantification of ARE/Nrf2 mediated gene expression. The cultivation was done under different environmental conditions. The processing included fermentation and cooking; postharvest ultraviolet irradiation (UV-C) treatment was also investigated. Overall, extracts showed strong health promoting potential, the highest potential was observed with the fermented extract, which showed a 60% reduction of AFB₁ induced DNA damage and a 38% reduction in FeSO₄ induced oxidative stress. The content of total polyphenols, carotenoids and chlorophylls was indeed affected by cultivation and processing. Based on the present findings consumption of leaves could be further encouraged, preferentially after cooking or fermentation of the plant.
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.