Nicotinamide and picolinamide in phospholipid monolayers

Abstract

AbstractMolecular dynamics simulations have been performed to investigate the interactions between nicotinamide (NA) and picolinamide (PA) with Langmuir monolayers of zwitterionic lipids: dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). Our results for the DMPC monolayers show that both NA and PA molecules are essentially found at the lipid/water interface and present orientational disorder of the molecules. In the case of DMPE monolayers, the pyridine nitrogen seems to be located deeper inside the monolayer than the amide group, for both isomers, being the effect higher for PA. We have computed electrostatic surface potentials and found qualitatively good agreement with experimental results. The different orientation and specific interactions of each molecule determine changes in the head orientation of the phospholipids, as the case of PA in DMPE monolayers, or in the orientation of the water dipoles, as it is the case of PA in DMPC monolayers. Through these analyses, we were able to capture the main contributions to the electrostatic potential in each system. © 2012 Wiley Periodicals, Inc.