A Comparative Study on the Bioactivity and Mineral Content of Different Grapevine (Vitis vinifera L.) Leaves Cultivated in Türkiye

The mineral composition, total phenolic content, radical scavenging, and antibacterial activity of 17 Vitis vinifera L. leaves obtained from vineyards in northeast Türkiye were investigated in this study. The antibacterial activities of grapevine leaf extracts were investigated by the disk diffusion method against five bacterial strains, and all leaf extracts showed inhibitory activity on both Bacillus cereus and Staphylococcus aureus. The radical scavenging activity of grapevine leaf extracts was evaluated using the DPPH (2,2-diphenyl-1-picryl hydrazyl) and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) assays. The ‘Gineş’ cultivar had the highest level of radical scavenging activity, while the ‘Ciklap’ cultivar had the lowest. The total phenolic content of leaf extracts was in the range of 172.66–483.33 µg GAE/mg DW. Grapevine leaf extracts were examined in terms of 15 different elements. The most abundant element in varieties of grapevine leaves was potassium, and its concentration varied between 5208.83 and 13,586.49 mg/kg. The results indicated that V. vinifera L. leaves had strong antioxidant and antibacterial activity, and the varieties of grapevine had a significant impact on these parameters (p < 0.001). Mineral and trace element contents were also significantly affected by cultivars (p < 0.05).