Interaction of procyanidin B₃ with membrane lipids - Fluorescence, DSC and FTIR studies

Procyanidins, contained in many products abundant in human diet, exhibit high biological activity. However, this activity has not been fully explained at cellular and molecular levels. In this study, we determine the mechanism of interaction of procyanidin B₃ with model lipid membrane. This mechanism was established on the basis of changes induced by B₃ in the physical properties of lipid bilayer. The changes were investigated using steady state and time-resolved fluorescence, DSC, and FTIR. We show that procyanidin B₃ causes changes in the arrangement of the polar heads of lipids, order of their acyl chains and the main lipid phase transition temperature. Furthermore, its presence in the membrane leads to a reduction in membrane dipole potential. Procyanidin B₃ is anchored to membrane via hydrogen bonds formed between its OH groups and the PO^2- and CO groups of lipids, causing changes in both hydrophilic and hydrophobic regions of the membrane.