Antioxidant activity of grape seed and skin extract during ripening

Reactive oxygen species (ROS) play an important physiological role in the body’s defense and being involved in numerous signaling pathways 1, 2. When the balance between oxidant and antioxidant species is altered in favor of ROS, oxidative stress is generated. In this condition the cells are damaged as the ROS oxidize important cellular components, such as proteins, lipids, nucleic acids and carbohydrates. The damage caused at the cellular level has repercussions on a systemic level favoring the appearance of various chronic and inflammatory diseases, such as cancer, cardiovascular diseases, type 2 diabetes and Alzheimer’s disease 3, 4. A way to keep the equilibrium in the organism is the intake of alimentary antioxidants that work synergistically with the endogenous ones to keep the good state of health. Dietary polyphenols are one of the most important groups of natural antioxidants, they are secondary metabolites found in fruits, vegetables, cereals, tea, wine. Grape is known to be one of the richest foods in polyphenols and the antioxidant activity of the grape is directly related to the phenolic concentration and composition, which varies during the ripening. In this work the antioxidant activity of grape seed and skin extracts of the red varieties Syrah, Tannat and Merlot during the ripening were evaluated through in vitro assays. The reference method Folin-Ciocalteu was used for the determination of the total polyphenol content (TPC) and the total antioxidant capacity (TAC) was determined through the radical scavenging assay using 1.1 -diphenyl-2-picrylhydrazyl (DPPH).5 The results of the analyses show that the seed extracts were richer in polyphenols than the skin extracts and had the highest antioxidant potential for all the grape ripening stages. The highest TPC and TAC values were found at the green stage for skins, at veraison for seeds.