The formation of three major pigments has been detected in model solutions imitating wine containing malvidin 3-monoglucoside (Mv-3-glu) and procyanidin B2 in the presence of acetaldehyde. Two of them were reddish-blue compounds whose visible spectra are bathochromically shifted with regard to that of Mv-3-glu. They were assigned to two enantiomers containing Mv-3-glu and B2 moieties linked across their C-8 by an ethyl bridge. A molecular ion at m/z 1097, consistent with such a structure, has been established by LC/MS for both of them. The third majority pigment was an orange-red product possessing a spectrum with a maximum wavelength in the visible region at 511 nm and a molecular ion at m/z 1093. A possible structure containing two flavylium mesomeric forms, corresponding to malvidin and to pelargonidin, has been suggested for this compound. This pigment proved to be more stable than the first two, as well as more resistant to discoloration by increased pH values and SO 2 . Similar pigments, whose spectra possess maximum wavelengths in the visible region between 490 and 511 nm, have also been found in equivalent solutions containing other flavan-3-ols [(+)-catechin, (-)-epicatechin, or procyanidin B3]. Evidence for the formation in red wine of pigments with similar spectral characteristics is also contributed.

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The NADPH oxidase enzyme system is the main source of superoxide anions in phagocytic and vascular cells. NADPH oxidase-dependent superoxide generation has been found to be abnormally enhanced in several chronic diseases. Evidence is accumulating that polyphenols may have the potential to improve cardiovascular health, although the mechanism is not fully established. Consumption of concentrated red grape juice, rich in polyphenols, has been recently shown to reduce NADPH oxidase activity in circulating neutrophils from human subjects. In the present work we studied whether red grape juice polyphenols affected NADPH oxidase subunit expression at the transcription level. For this, we used human neutrophils and mononuclear cells from peripheral blood, HL-60-derived neutrophils and the endothelial cell line EA.hy926.Superoxide production was measured with 2 0 7 0 -dichlorofluorescein diacetate or lucigenin, mRNA expression by real-time RT-PCR and protein expression by Western blot. Each experiment was performed at least three times. In all cell types tested, red grape juice, dealcoholised red wine and pure polyphenols decreased superoxide anion production. Red grape juice and dealcoholised red wine selectively reduced p47phox, p22phox and gp91phox expression at both mRNA and protein levels, without affecting the expression of p67phox. Pure polyphenols, particularly quercetin, also reduced NADPH oxidase subunit expression, especially p47phox, in all cell types tested. The present results showing that red grape juice polyphenols reduce superoxide anion production provide an alternative mechanism by which consumption of grape derivatives may account for a reduction of oxidative stress associated with cardiovascular and/or inflammatory diseases related to NADPH oxidase superoxide overproduction.

With the aim of understanding the effects of water stress and cluster load on berry composition and wine quality, a four-year field test was conducted in a cv. Tempranillo vineyard in Extremadura (Spain). When the first berries appeared to be changing colour (onset of véraison), grapevines were subjected to two different irrigation regimes, one supplying 100% of crop evapotranspiration, and the other 25%. In addition, two cluster load levels were tested for each irrigation regime: seven to nine and four to five clusters/m 2 planting area. Both irrigation and thinning had an impact on most of the parameters analysed in the grapes and the wines, although the thinning effect was in general higher than the irrigation effect. Thus, deficit irrigation reduced malic acid and the titratable acidity of Tempranillo grape juice, while cluster thinning increased all parameters analysed, except potassium concentrations. Similarly, the wine composition was also affected differently by irrigation and by cluster thinning. Deficit irrigation reduced pH and increased titratable acidity, total phenol index and colour parameters, while cluster thinning increased alcohol content, anthocyanin and colour intensity, and reduced pH and colour. The effect of the cluster thinning technique was independent of the irrigation regime in most of the wine parameters analysed, except for total phenol index, where the effect of deficit irrigation (DI) was more pronounced in grapevines also subjected to the cluster thinning treatment.