Cytotoxicity of polyphenolic extracts from Mediterranean foods on Hepatoma Cell Line (HepG2).

The antioxidant and anticancer properties of polyphenols present in plants and several beverages (i.e red wine, green tea) have been largely explored in the literature. Within the framework of RiSaNA (Local Products with Healthy Properties to Obtain New Functional Foods) project, financed by the Italian National Research Council, we performed an in vitro analysis of polyphenolic extracts prepared from two Mediterranean cultivars: artichoke (Violetto di Provenza variety) and apple (Annurca variety) on human hepatoma cell line (HepG2). Polyphenolic content and antioxidant power of extracts were determined by Folin-Ciocalteu and FRAP assays. Using crystal violet staining, we showed that apple extract reduced cell viability up to 40% at a concentration of 500 µg/ml. In the case of artichoke extract, the strong reduction in cell viability (up to 60%) registered at the highest concentration tested (> 850 µg/ml) was partially attributable to the production of hydrogen peroxide in cell culture medium. In addition, we reported a slight reduction of intracellular ROS (reactive oxygen species) in HepG2 cells treated with apple extracts, suggesting their ability to interfere with ROS homeostasis in regulating cell death. In particular, following exposure of 250 ?g/ml of apple polyphenolic extract we observed morphological characteristic of type II cell death (autophagy), while lower concentrations (25-50 ?g/ml) were able to reduce clonogenic survival in HepG2 cells.