Evaluation of bioactive compounds and antioxidant capacity in leaves of Vitis vinifera L. cv. Aglianico and Falanghina

Abstract Aligning with the circular economy principles and the valorization of agri-food wastes, this study investigated the major bioactive compounds in leaves of two representative grapevine cultivars from Campania region in Italy: Aglianico and Falanghina. Key phytochemicals, such as carotenoids, tocols, total and single polyphenols, were analysed through chromatographic and advanced mass spectrometry techniques (HPLC-DAD-FLD and HPLC-ESI-Q-TOF MS). Antioxidant capacity was evaluated using the DPPH, CUPRAC, ABTS assays. The most representative tocols were α-tocopherol (maximum values of about 200 mg/100 g f.w.) and γ-tocopherol (highest levels of 80 mg/100 g f.w.), while β-carotene and lutein were the predominant carotenoids (highest amounts about 15 and 25 mg/100 g, respectively). Caftaric acid and quercetin-3- O -glucuronide were the major phenolic compounds. Considering the Recommended Daily Allowance (RDA) established by EU Regulation, 100 g of the analysed leaves provide significant amounts of vitamins A and E. Seasonal monitoring (from June to November) revealed that the concentrations of the investigated bioactive compounds varied significantly across leaf developmental stages, with carotenoids and total phenols decreasing and tocols increasing during the phenological stages. Results showed that a good period of harvesting could be in September, after the grape harvest.