Polyphenols of peanut (Arachis hypogaea L.) skin as bioprotectors of normal cells. Studies of cytotoxicity, cytoprotection and interaction with ROS

Arachis hypogaea L. (peanut) skin is a potential source of natural antioxidants, and several studies have suggested the possibility of producing functional ingredients from this by-product of food industry. This investigation examined possible toxic effects of peanut skin polyphenolic extract (PSE) and its antioxidant properties using in vitro studies. PSE and its main component quercetin (QE) did not present any cytotoxicity on normal epithelial cells, rat ileum cells (IEC-18), monkey kidney cells (Vero) or human peripheral blood mononuclear cells (PBMCs) at concentrations with antioxidant effects. QE and PSE showed scavenging of the superoxide anion radical and cytoprotection, as well as reducing the reactive oxygen species (ROS) and superoxide dismutase (SOD) activity in IEC-18 cells against menadione-induced oxidative stress. This suggests that peanut skin phenolic extract could be a potential functional ingredient for foods.