Synergy Study of the Inhibitory Potential of Red Wine Polyphenols on Vascular Smooth Muscle Cell Proliferation

Vascular smooth muscle cell (VSMC) proliferation contributes to the development of atherosclerosis. Red wine consumption due to the polyphenol content has been reported to counteract atherosclerosis progression possibly through inhibition of VSMC proliferation, among other mechanisms. In this study we investigate the antiproliferative activity of four wine polyphenols: resveratrol, quercetin, ethyl gallate, and (+)-catechin in rat aortic VSMC. All four polyphenols inhibited serum-induced VSMC proliferation when applied as a single treatment. To further address a potential synergistic action of the investigated polyphenols, the antiproliferative effect of different combinations in equimolar, as well as equipotent ratios were quantified. The IC50 values of single polyphenols regarding the inhibition of VSMC proliferation ranged from 49.58 mu M to 86.06 mu M. However, apparent inhibitory efficacy of each compound increased by a factor of 10.4 in the quadruple equipotent mixture, as calculated from the dose-reduction index. Thus, the effective IC50 values of each of the four mixture constituents ranged from 4.76 mu M to 8.27 mu M. The calculated combination index (CI, where CI <, =, or > 1 indicate synergy, additivity, or antagonism, respectively) values of equimolar combinations of the polyphenols indeed indicated mainly synergy (CI ranging from 0.24 +/- 0.01 to 1.51 +/- 0.13). Optimized equipotent mixture showed enhanced synergy (CI ranging from 0.18 +/- 0.04 to 1.36 +/- 0.26). In conclusion, we show for the first time that four major polyphenols from wine synergistically inhibit VSMC proliferation.