Polyphenols from Vitis vinifera L. Grape Stems Regulate Alcohol Metabolism and Reduce Its Toxic Effects in Rats

The study evaluated the effect of a Vitis vinifera L. grape stem extract (GSE, obtained from the smaller woody parts of a grape cluster separated from berries) enriched with a polyphenolic complex on ethanol elimination from the body and alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities in the liver of rats under conditions of chronic alcohol intoxication. In the resulting extract, the total polyphenol content was 53.12 ± 1.25 mg GA/g (Gallic Acid mg-equivalents) dry weight, and flavonoids—8.02 ± 2.6 mg Q/g (Quercetin mg-equivalents) dry weight. Added to a 15% ethanol solution, 5% GSE caused a reduction in ethanol consumption by the animals, under conditions of both free-access and forced ethanol consumption. A comparative analysis of the ethanol pharmacokinetic parameters in the blood of rats showed that GSE supplementation leads to a decrease in ethanol elimination from the body, as evidenced by an increase in its half-life (T1/2) and a reduction in its elimination rate constant (Kel). It was established that the polyphenolic complex, contained in the plant-derived extract, plays a significant role in ethanol metabolism, affecting the enzymes involved in its oxidation. GSE action leads to an increase in hepatic ADH reductase activity, which helps prevent the accumulation of highly toxic acetaldehyde in the organism. This fact is confirmed by a decrease in hepatic ALDH activity in rats, with both low and high Michaelis constants. The polyphenolic complex isolated from the grape cluster stems may become an effective means for protecting the organism against the toxic effects of high doses of ethanol.