Previous studies have shown that Red Wine Phenolic extracts induce nitric oxide (NO)-mediated vasoprotective effects, mainly by causing a redox-sensitive activation of endothelial NO synthase (eNOS). However, Red Wine Phenolic extracts are complex mixtures of a several hundreds of phenolic compounds. Therefore, the aim of the present study was to isolate active phenolic compounds using multi-step bioguided fractionation of the red wine extract.

Red Wine Phenolic Extract was submitted to a bioguided fractionation using chromatographic methods. The fractions obtained at each step were tested for their potential to induce the activation of eNOS in endothelial cells. Cultures of porcine coronary artery endothelial cells (P1) were used to determine the phosphorylation level of Akt and endothelial NO synthase by Western blot analysis. Identification of phenolic compounds in each active fraction was performed by MALDI-TOF and HPLC-MS techniques.

The first step of fractionation on lipophilic Sephadex® yielded 9 fractions of which 4 of them significantly increased the phosphorylation level of Akt and eNOS in endothelial cells. The active fractions contained mainly procyanidins and some anthocyanins compounds. The fractionation of one of the active fractions by preparative reverse-phase HPLC yielded 11 subfractions ; all of these sub-fractions significantly increased the phosphorylation level of Akt and eNOS. The analysis of the phenolic compounds indicated that these sub-fractions contained mixtures of procyanidin dimers or conjugated anthocyanins.

The red wine extract contains several types of phenolic compounds, which are able to enhance the activity of NO synthase in endothelial cells including procyanidins dimers and oligomers as well as several conjugated anthocyanins.