**8. Influence of the anthocyanins in the antioxidant activity of wines**

Anthocyanins are the most abundant polyphenolic compounds in red wines. Red wine is probably the foodstuff that presents the highest diversity of these polyphenolic pigments in their original form and in other derivative structures. Various studies in vitro and in vivo have confirmed that wine has antioxidant properties, mainly attributable to its composition rich in phenolic compounds [296–298], which vary from 1200 to 2400 mg/L [299–303].

Wines, particularly red wines, inhibit platelet aggregation, increase antioxidant capacity in humans and reduce the susceptibility to lipidic peroxidation in plasma [45, 304–306]. Anthocyanins are the pigments responsible for the attractive colour of red wine and are one of the main flavonolic compounds with antioxidant activity, which is why red wine has a greater antioxidant activity than white wine [307–310]. Its antioxidant capacity can be up to 10 times stronger than that of white wine [205].

Nevertheless, alcohol itself has a protective effect as, to some extent, it is a mediator of the increase (close to 50%) of the level of high‐density lipoproteins (HDLs) and of the decrease (of around 18%) of low‐density lipoproteins (LDLs), such as cholesterol [311, 312]. However, various studies have correlated the effect of the consumption of red wine with a reduction in coronary heart disease, which is more significant than that for beer or other alcoholic drinks [18, 45]. Therefore, this reduction can be attributed to nonalcoholic components present in red wine [304, 307].

The nonalcoholic components of wine, mainly phenolic compounds, are considered to be the primary factor responsible for this protective effect. There is a significant concentration of flavonoids in red wines (>500 mg/L) and a very low one in white wines (<60 mg/L) [313–315]. In a study by Frankel et al. [300], the relative antioxidant activity of 20 Californian wines was mainly correlated with the presence of cyanidin and malvidin 3‐glucoside. Similar results were obtained by Aguirre et al. [316] and Rivero‐Pérez et al. [317, 318] in Chilean and Spanish red wines, respectively. According to Fernández‐Pachón et al. [319], in the ranking of activity, the most active is the anthocyanins and flavan‐3‐ol, followed by the phenolic and flavonol acids.

Ghiselli et al. [320] studied three polyphenolic subfractions of red wine, evaluating the capacity to trap hydroxyl and peroxyl radicals, the inhibition in vitro of the oxidation of LDLs and platelet aggregation. The fraction containing the anthocyanins proved to be the most effective in its capacity to trap ROS and to inhibit the oxidation of LDLs and platelet aggregation. Anthocyanins are quantitatively the most abundant phenolic subclass in red wine [321, 322]. The other two fractions, containing the phenolic acids and quercitin 3‐glucuronide, and procyanidins, catechins and quercitin 3‐glucoside, are less active.

Some authors still attribute the antioxidant activity of red wines to all polyphenolic compounds [323–325], not discarding the hypothesis that the different classes of polyphenolic compounds can be more effective and act in a synergistic way. However, according to Fernández‐Pachón et al. [319], no synergistic effects were observed among the isolated fractions of red wines (anthocyanins, flavonols and phenolic acids). Galanakis et al. [326] characterized the phenolic content and antioxidant capacity of Cypriot wines. The higher concentrations of phenols did not always reflect higher antioxidant capacity of wines, probably due to the observed antagonistic effect between hydroxycinnamic acid derivatives, flavonols and anthocyanins.
