Nutritional constituents, phytochemical profiles, in vitro antioxidant and antimicrobial properties, and gas chromatography-mass spectrometry analysis of various solvent extracts from grape seeds (Vitis vinifera L.)

The present study revealed that the nutritive value of grape seeds (Vitis vinifera L.) was 383.55 +/- 0.13 Kcal/100 g, with magnesium as the most abundant mineral element (70.44 +/- 0.88 mg/L). The maximum phenolic (392.58 +/- 1.70 mg of GAE/g), flavonoid (256.16 +/- 1.60 mg of QE/g), and tannin (30.95 +/- 0.17 mg of CE/g) contents were also found in the ethanol, dichloromethane, and hexane extracts, respectively. The major phytochemical compounds in the ethyl acetate extract were identified via gas chromatography mass spectrometry (GC MS) analysis. The ethanol extract has the highest antioxidant activity (IC50=140 +/- 1.20 mu g/mL for DPPH, 145.28 +/- 0.45 mg alpha-tocopherol/g for total antioxidant capacity, and EC50=80 +/- 1.41 mu g/mL for ferric-reducing power assays). For beta-carotene test, the highest antioxidant activity was obtained in the hexane extract. A satisfactory antimicrobial activity was found against a panel of microorganisms with the ethyl acetate extract as the best antimicrobial agent. Additionally, it was found that the bactericidal concentration required for the grape seed extract to kill Listeria monocytogenes should be less than 12.50 mg/mL (minimum inhibitory concentration=4).