Hypolipidemic and antioxidant effects of hydroxycinnamic acids, quercetin, and cyanidin 3-glucoside in hypercholesterolemic erythrocytes (in vitro study)

OBJECTIVE: Four polyphenols: ferulic acid and p-coumaric acid (hydroxycinnamic acids), quercetin (flavonol) and cyanidin 3-glucoside (anthocyanin) were selected, and their antioxidant properties and their influence on cholesterol concentration in hypercholesterolemic and normal erythrocytes were investigated. METHODS: To determine the effect of phenolic compounds, we prospectively studied cholesterol concentration, lipid peroxidation and membranes fluidity. Whole-blood and isolated erythrocytes (2% hematocrit) were incubated for 24 h with selected compounds at concentration 1, 10 and 100 μmol/L. All investigated compounds decreased lipid peroxidation in whole blood. Cyanidin 3-glucoside and quercetin showed higher antioxidant properties than hydroxycinnamic acids (ferulic acid and p-coumaric acid). RESULTS: Incubation of whole blood of hypercholesterolemic patients with quercetin and cyanidin 3-glucoside resulted in statistically significant reduction of cholesterol concentration in erythrocytes down to 75% (at 10 μmol/L of polyphenols) and 69% (at 100 μmol/L of polyphenols) of initial values. The effect of both compounds on isolated erythrocytes was even more pronounced, reduction down to 70% (at 10 μmol/L of polyphenols) and 58% (at 100 μmol/L of polyphenols) of initial values. After incubation of isolated erythrocytes of hypercholesterolemic patients with quercetin and cyanidin 3-glucoside, increase of membrane fluidity was noticed. After incubation of isolated erythrocytes of healthy donors with investigated compounds, no changes in membrane fluidity were observed. CONCLUSION: Our results indicate that flavonols and anthocyanins have higher antioxidant properties and higher influence on cholesterol concentration in erythrocytes membranes than simple hydroxycinnamic acids.