Antioxidant effect of red wine polyphenols on red blood cells

Protective effect of quercetin against cigarette tar extract-induced impairment of erythrocyte deformability

Quercetin (3,3',4',5,7-pentahydroxyflavone) is one of the most abundant flavonol-type flavonoids rich in diet and suggested to possess a beneficial role in blood circulation. This study was conducted to know the effect of quercetin aglycone and one of its possible metabolite, quercetin-3-O-beta-D-glucuronide on cigarette tar extract-induced impairment of erythrocyte deformability. Erythrocyte suspension containing quercetin aglycone, quercetin-3-O-beta-D-glucuronide or quercetin-3-O-beta-D-glucoside was forced to flow through microchannels with equivalent diameter of 7 &mgr;m and its transit time was measured as an index of erythrocyte deformability using microchannel array method. Both quercetin aglycone and quercetin-3-O-beta-D-glucuronide, but not quercetin-3-O-beta-D-glucoside, substantially increased erythrocyte deformability indicating that the former two compounds affect the physicochemical state of erythrocyte by interacting with its membranes. Aqueous cigarette tar extract caused marked decrease in erythrocyte deformability with concomitant increase of membranous lipid peroxidation. In that case, quercetin aglycone suppressed the impairment of erythrocyte deformability as well as membranous lipid peroxidation. The same effect was found in quercetin-3-O-beta-D-glucuronide, eventhough its effect was lower than that of quercetin aglycone. Thus, not only quercetin aglycone but also its conjugate metabolite protects erythrocyte membrane from the damage of smoking by scavenging reactive oxygen species generated from cigarette tar. Intake of quercetin-rich food may be helpful to protect membranous damage in erythrocytes from smoking.

Chemical studies of proanthocyanidins and hydrolyzable tannins

We investigated a number of natural polyphenols representing flavan-3-ols, gallotannins, and ellagitannins with regard to their antioxidant potential. For this purpose we used pulse radiolysis to determine scavenging rate constants with hydroxyl radicals and decay rates of the respective aroxyl radicals and EPR spectroscopy to identify the radicals after in situ oxidation. Using NMR spectroscopy, we could confirm phenolic coupling reactions of epigallocatechin gallate and pentagalloyl glucose after radical-induced oxidation.

Antioxidant effect of red wine anthocyanins in normal and catalase-inactive human erythrocytes

Previous studies reported that aged red wine, but not novel red wine or white wine protects human red blood cells from oxidative damage induced in vitro by H(2)O(2.) Here, we demonstrate that the beneficial properties of aged red wine are due, at least in part, to the presence of anthocyanins. We firstly measured the "antioxidant power" of an Italian red wine (Taurasi, Avellino) and that of its anthocyanin fractions by using Ferric Reducing Antioxidant Power Assay. Subsequently, we demonstrate that fractions containing anthocyanins lower ROS (reactive oxygen species) and methemoglobin production in human erythrocytes treated with H(2)O(2.) Finally, we reported that the protective effects of anthocyanins were also confirmed in an experimental model in which RBCs were deprived of catalase activity by treatment with 4 mM sodium azide. The results obtained clearly demonstrate that red wine anthocyanins protect human RBCs from oxidative stress.