Bioactivity of Leaves, Skins and Seeds of Berry Color Variant Grapevines (Vitis vinifera L.)

Abstract

Grapevine synthesizes a wide variety of polyphenolic compounds, which can be beneficial both the plant and human health, due to their antioxidant effects. In this study, total antioxidant capacities (TAC), flavonoid and flavanol content in various plant parts of berry color variants (V. vinifera L. conc. Goher) were evaluated for the first time. The current research aimed to examine the effect of sunlight exposure on the accumulation of polyphenolic compounds in shaded and sun exposed leaves and also included the measurements of berry skins and seeds. Two electron transfer based techniques were used for antioxidant analyses; Trolox Equivalent Antioxidant Capacity (TEAC) and Ferric Reducing Antioxidant Potential (FRAP). In addition, Total Reducing Capacity (TRC) and relative amounts of compound groups such as flavonols and flavanols were measured using photometric assays. Our results revealed significant differences in the studied parameters among the varieties and their different tissues. Furthermore, we documented different sunlight acclimation of leaves in terms of differently increased TAC values and flavonoid content. Our study proved that grapevine leaves contain more antioxidants than berry skins and they have more varied antioxidant composition than seeds, therefore this plant part is an excellent source of bioactive compounds, applicable for food, chemical and pharmaceutical industries.