Direct Action of Sesamin on Model Lipid Membranes

Objective: This study examines the influence of the lipid-soluble lignan sesamin on the physical properties of model lipid membranes. Its ability to alter the transmembrane distribution of electrical potential and the lipid packing in membranes containing neutral phosphatidylcholines (PC) and negatively charged phosphatidylserines (PS) was assessed. Methods: Electrophysiological method for determining changes in electrical potential at the membrane/aqueous solution interface and differential scanning microcalorimetry for measuring the thermodynamic characteristics of lipid vesicles. Results: Sesamin was found to reduce the membrane boundary potential regardless of membrane composition, with the effect not exceeding 20 mV. It was also shown to significantly affect the main temperature, peak width, and phase transition enthalpy of PC membranes, with the effect decreasing as the acyl chain length of the lipid increased. Furthermore, sesamin induced a decrease in the phase transition temperature of PS and the formation of additional mixed lipid–sesamin phases. Conclusion: These results suggest that sesamin reduces lipid packing density in membranes and warrant further investigation of how these effects contribute to its pharmacological activity.