Total phenolic and flavonoid contents, antioxidant and antimicrobial activities of traditional unripe grape products

Abstract

Unripe grape products, unripe grape juice (or koruk juice), unripe grape powder and unripe grape piece are common condiments in Kilis traditional cousin. Besides their taste roles, their probable health benefits were also studied in this work. To evaluate total phenolic and flavonoid contents, antioxidant capacity and antimicrobial activity of unripe grape samples (juice, powder and piece) extracted by various solvents. Samples were extracted separately by ethanol and distilled water (10%). Concentrated samples were suspended in methanol to final concentration 100 mg/mL. Percentage yield in the extracts were observed to range from 4.19 to 17.76. While the total phenolic contents of ethanol and distilled water extracts were revealed to range from 505.682 to 758.523 and 424.432 to 603.409 mg GAE/g; total flavonoid contents of extracts were 0.073 to 0.147 and 0.041 to 0.055 mgRE/g, respectively. Antioxidant capacity of extracts was calculated between 64.07(ethanol) and 82.64 % (distilled water). Studied extracts showed antimicrobial activity against only one test microorganism, C. albicans. The highest antibacterial activity (8 mm) was observed in unripe grape piece distilled water extract.