Wine antioxidants: Effects in vitro and in vivo

Abstract

The antioxidant capacity of wine and plasma was assessed adopting a kinetic procedure [2], while plasma lipid hydroperoxides were measured by a single photon counting chemiluminescence technique [4]. In the adopted procedure, the antioxidant capacity of the wine (or the plasma) is expressed in terms of the concentration of the soluble analogue of α-tocopherol (Trolox C) producing the same antioxidant effect. The procedure is specifically addressed to the major kinetic constrains of the antioxidant effect, i.e., the peroxyl radical scavenging and the formation of a less reactive radical. This is obtained by analyzing the kinetics of competition of a parallel reaction where peroxyl radicals bleach the carotenoid crocin. Several wines have been analyzed as well as the effect of time of contact with skins and seeds during fermentation, aging and re-oxygenation. As expected, red wines were dramatically more active than white wines, apparently due to the anthocyanin content. Actually, phenolic acids, catechins, anthocyanin monomers, flavonols and anthocyanin polymers, all contribute to the antioxidant activity of wine. These fractions have been separated by solid phase extraction [1] and analyzed by HPLC and for the antioxidant capacity. In a typical example, the antioxidant capacity of a five-year old red wine (Schioppettino) is accounted for by: anthocyanins 55%, tannins 25%, flavonols 15%, hydrosoluble phenolic acids 5%. Accordingly, the UV-VIS analysis of the so-called “color intensity” (Abs520+Abs420), carried out on the same wine, produced in different years is highly correlated to the antioxidant capacity (R = 0.99), in agreement with the relevance of anthocyanin monomers and anthocyanin polymers on the overall antioxidant capacity. The administration to fasting volunteers of 300 ml of a young red wine with a very high antioxidant capacity (42 mM Trolox) produced an average increase of plasma antioxidant capacity, of 88± 18%