Simulação, por dinâmica molecular, das interações água-etanol-NaCl com fosfolipídeos de membrana

Abstract

Erythrocytes or red blood cells are single cells among mammalian cells. They contain no organelles and nucleus, containing hemoglobin inside, surrounded by a membrane. They are responsible for transporting oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs, which makes its integrity important for the proper functioning of the whole organism. One of the substances that may cause effects on erythrocyte membrane is ethanol, found in a wide variety of products. In this work, the interactions between ethanol, water and sodium chloride with membrane phospholipids was evaluated using experimental assays combined to molecular dynamics approach. The blood of two young rats was used to evaluate the effect of increasing concentrations of ethanol, 0-50% (v/v) on the osmotic fragility of the cells. In addition, a theoretical study involving molecular dynamics simulation was performed using the software package GROMACS, in which dipalmitoylphosphatidylcholine - DPPC was used as membrane model. GROMOS 53a6 force field was used in the computer simulations, considering a time of 60 ns for each system. The experimental results show that increasing ethanol concentration raises the lyse of the erythrocytes. However, for values higher or equal to 35% (v/v), the lysis is reduced. The theoretical data illustrated the affinity of ethanol by the membrane lipids, generating changes in the charge orientation along the bilayer, forming pores, changing the permeability and deforming the bilayer in high concentration of ethanol. It is noted, in this study, that the deleterious effect of ethanol on the erythrocyte membrane is non-dose dependent and that it acts, by interaction, with the structure of the lipid bilayer.