Quercetin Induces Lipid Domain-Dependent Permeability

In this work, we present our results on quercetin interaction with distinct model membranes exploring the importance of lipid phases, ld, ld/lo and ld+lo+so, to the action of this flavonoid in bilayers and possibly contributing to clarifying some controversial aspects related to quercetin multiple activities. We found out that quercetin is able to increase membrane permeability in a manner dependent on the presence and characteristics of lipid domains. In the presence of sphingomyelin, we found the greatest increase in mean membrane permeability (at least 10 times higher than the other lipid compositions). We also observed the presence of micrometric domains whose shape and size were disturbed by the action of quercetin. The presence of cholesterol increased membrane rigidity. This effect was enhanced with the presence of quercetin, but for chol-sphingomyelin combination, the bilayers became more flaccid at low quercetin/lipid proportions (< 1/5) and moderately rigid at proportions of the 1/1 order. The affinity parameters were higher for the most homogeneous systems and with larger areas and extensions of disordered liquid phase than for those systems of higher heterogeneity.