Exploring the phytochemical profile of red vine (Vitis vinifera L.) leaves: compositional assessment of commercial samples.

This study investigated the composition of commercial red vine (Vitis vinifera L.) leaves, assessing the nutritional composition, the carotenoid and chlorophyll content, and the polyphenolic fractions. Interestingly, marked variability was observed for all the components analyzed, evidencing significant inter-lot differences in both quantitative and qualitative profiles. Following a preliminary optimization of the extraction process, the polyphenolic fraction was deeply investigated through LC-MS. Total anthocyanin content, quantified as cyanidin-3-O-glucoside equivalents, ranged from 0.49 to 5.64 mg/g d.m. The sum of phenolic acids varied between 1.15 and 2.33 mg/g d.m., while flavanols and flavonols collectively ranged from 4.91 to 9.59 mg/g d.m. Antioxidant activity, assessed via the DPPH and ABTS assays, was positively correlated to the total phenolic content. Overall, the chemical differences detected across commercial red vine leaves indicate limited standardization of raw materials and support the need for defined compositional criteria to ensure consistent function performance of these botanical ingredients.