40 mg/100 g) being observed for Merlot. Studies have shown that resveratrol is a potent antimutagenic, antioxidant, anti-inflammatory, and antiproliferative agent, as well as an inhibitor of cyclooxygenase and hydroperoxidase

in diverse experimental systems ( Aziz et al., 2003 and Jang et al., 1997). Gallic acid, a non-flavonoid phenolic acid quantified in all the samples of grape pomace, was present in highest concentration (18.68 mg/100 g) in the Bordeaux variety. The range of values coincides with those reported by other authors (Montealegre et al., 2006 and Yilmaz and Toledo, 2004). Concerning the study of antioxidant effectiveness, the use of different in vitro models has recently been recommended, due to the differences

between the various free radical-scavenging assay systems ( Ruberto et al., 2007). Thus, the determination of the Selleckchem Depsipeptide antioxidant activity of the extracts was carried out using the ABTS and DPPH methods and reducing power Selleckchem Erastin through the FRAP method ( Table 1). The Cabernet Sauvignon variety had greater antioxidant activity (485.42 and 505.52 μMol TEAC/g by ABTS and DPPH methods, respectively) and reducing power (249.46 μMol TEAC/g by FRAP method) than the other varieties evaluated. Significant differences were observed (P < 0.05) among the varieties. In a previous study on red grape pomaces from Regente and Pinot Noir varieties ( Rockenbach et al., 2007), mean values of 419 and 477 μMol TEAC/g were obtained using the ABTS method and 479 and 480 μMol TEAC/g through the DPPH method, respectively. In comparison, Pérez-Jiménez et al. (2008) reported antioxidant activity values lower Casein kinase 1 than these (124.4 μMol TEAC/g by ABTS method) for red grapes produced in Manzanares, Spain. However,

the value for reducing power was higher (273.9 μMol TEAC/g using the FRAP method) than those found in the present study. This may be due to the redox potentials of the individual phenolic compounds and their structural properties, such as hydroxylation level and extension of conjugations ( Pulido, Bravo, & Saura-Calixto, 2000). In the study by Sánchez-Alonso et al. (2008) cited above, dietetic fibre obtained from grape pomace of the Airén variety showed an antioxidant activity of 284 μMol TEAC/g using the ABTS method, a value lower than that found for most varieties evaluated herein. Besides showing good antioxidant activity and significant reducing power, grape pomace extracts also have a moderate capacity to inhibit the oxidation of the β-carotene/linoleic acid system (Fig. 3). In this study the β-carotene decolouring mechanism was evaluated in a system mediated by free radicals formed from linoleic acid. The presence of extracts with antioxidant activity can inhibit partially the loss of β-carotene colour through neutralisation of free radicals formed in the system, the % of oxidation inhibition being dose-dependent.