Determination of phenolic compounds content and antioxidant activity in skin, pulp, seed, cane and leaf of five native grape cultivars in West Azerbaijan province, Iran

In the present work, the phenolic compounds content and antioxidant activity in the skin, pulp, seed, cane and leaf of one international (Muscat) and five native (Hosseini, Ghara Shira, Agh Shani, Ghara Shani and Ghara Ghandome) grape cultivated in West Azerbaijan, Iran were investigated. Ghara Shani grape skin was found to contain the highest content of total phenolic and anthocyanin and cane of Ghara Shani contains the highest amount of flavonoid. A remarkable DPPH radical scavenging activity up to 95% and consequently, the lowest IC50 was found for skin of Ghara Shani. According to RP-HPLC experiments, the highest concentration of phenolic compounds was identified as catechin (945 μg/g), epicatechin (482 μg/g), gallic acid (319 μg/g) and resveratrol (29.8 μg/g) in skin of Ghara Shani, quercetin in cane of Ghara Shani (956 μg/g), rutin in skin of Ghara Shira (298 μg/g) and caffeic acid in cane of Ghara Shira (17.4 μg/g).