Antioxidant and cytoprotective activities of extracts prepared from fruit and vegetable wastes and by-products

In this study, fruit and vegetable wastes and by-products were tested for polyphenol content and their antioxidant activity. The highest content of polyphenols as assessed by the Folin–Ciocalteu assay was the hot-water extract of grape seed, followed by the ethanol extract of buckwheat hull. The highest antioxidant activity measured by 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assays was also detected in the hot-water extract of grape seed, followed by the ethanol extract of immature prune. Most of samples showed protective effects against oxidative stress induced by 2,2′-azobis-(2-amidinopropane) dihydrochloride (AAPH) peroxyl radical generator in African monkey kidney (MA 104) cells. Samples containing high amounts of phenolics (more than 30 mg ChAE/g) generally showed high antioxidant activity and a protective effect against AAPH-induced oxidative stress. This study demonstrates that fruit and vegetable wastes and by-products are good sources of high amounts of phenolics with antioxidant properties.