Preparation. Grape pomace from Vitis vinifera (Cencibel variety) was extracted following the method previously reported by SauraCalixto et al., 2007. Freeze-dried grape pomace was extracted by constant shaking at room temperature with methanol–water
(50:50 v/v, 50 mL/g sample, 60 min) and acetone–water
(70:30 v/v, 50 mL/g sample, 60 min). After each extraction step, samples were centrifuged (15 min, 25 °C, 3000 g) and supernatants were collected. At the end of extraction process, methanol–water and acetone–water supernatants were combined, concentrated under reduced pressure at 50 °C, freezedried and ground to fine powder (sieve ring 0.5 mm). Grape pomace extract was stored at − 20 °C until use