Wine has numerous beneficial aspects for human health thanks to the polyphenols it contains such as anthocyanins and resveratrol.
In fact, the polyphenols, present in both plants and fruits, perform a defensive action against external agents like bacteria and viruses. But the properties that have mainly attracted the attention of the mass media and researchers on polyphenols is their antioxidant action. This means that they are able to hinder the formation of free radicals and promote anti-aging processes.
Polyphenols are found in all parts of the grape, particularly in the skins, seeds and stalks. In particular, anthocyanins and flavonols are found in the grape skin, while phenolic acids are mainly concentrated in the pulp. Tannins are abundant in the grape seeds and, to a lesser extent, in the skin. One of the most popular polyphenolic compounds for all wine lovers are the tannins that come from the solid parts of the grapes (skins, pips and stalks) and pass into the wine during the maceration process (for this reason its presence is almost an exclusive of red wines, better if aged at least one year in barrel).

Sources: Pub Med