Grapevine leaves (Vitis vinifera): Chemical characterization of bioactive compounds and antioxidant activity during leave development

Leaves from Vitis vinifera L. represent the less studied and valorized wastes of grape crops and the winery industry. This study aims thus to perform for the first time a deepened assessment of the bioactive compounds in grapevine leaves. The detailed composition of main phytochemicals involved in the high antioxidant of grape leaves (2.20 g TE/100 g) was determined including carotenoids (lutein, β-carotene), tocopherols (α and ɣtocopherol), polyphenols (phenolics acids, flavonoids), and phytosterols (β-sitosterol). In particular, high levels of lutein (0.3–1.0 g/kg) and α-tocopherol (0.2–1.2 g/kg) were observed. Moreover, the evolution of bioactive compounds during 7 harvesting times from July to October was also studied showing that the content of phytochemicals fluctuates according to the development stage of grape leaves. Phytosterols for example reached their highest levels in leaves in the later stage of maturation (T6 – T7) with values around 169 ± 40 mg/kg.