ROS SPECIFIC AND GENERAL ANTIOXIDANT CAPACITIES OF GRAPEVINE LEAF PHENOLICS

Abstract

Grapevine is an important agricultural plant typically grown in sun exposed areas. In this study, we examined sun exposed Pinot noir grapevine leaves and their major phenolic compounds. HPLC measurements identified caftaric acid as major phenolic acid and glycosylated quercetins as main flavonoids in addition to smaller amounts of various glycosylated kaempferols. These secondary metabolites protect against oxidative stress such as ultraviolet radiation or excess visible light (photoinhibition), as UV-absorbers and/or antioxidants. These properties were assessed in leaves and phenolic compounds. Quercetin derivatives and caftaric acid showed higher total antioxidant capacities than kaempferols. Nevertheless, differences were significally influenced by the applied assays (Csepregi et al. 2016). Furthermore, we examined ROS specific antioxidant capacities against singlet oxygen and hydrogen peroxide which may be directed to avoiding photoinhibition or UV damage, respectively. We found that these properties were also influenced by polyphenol structure, similar to total capacities. Results of this study demonstrate the versatility of polyphenols in acclimation to sunlight. Supported by the Hungarian Scientific Research Found (OTKA K-112309). Csepregi, K., Neugart, S., Schreiner, M., Hideg, E., 2016, Comparative Evaluation of Total Antioxidant Capacities of Plant Polyphenols, Molecules, 21, 208