Efeito da solvatação aquosa nos parâmetros geométricos e eletrônicos da melatonina usando dinâmica molecular de Car-Parrinello

Abstract

Melatonin (5-methoxy-N-acetyltryptamine) is a hormone produced by the pineal gland from amino acid tryptophan. Once released into the bloodstream, melatonin presents several different types of bioactivities. Among the main bioactivities presented, highlightthe ability to remove free radicals, antioxidant activities, protective activity of DNA, circadian cycle regulation. It is possible that the broad spectrum of their bioactivities is related to the interaction of melatonin with the cell membranes. Consequently, the interaction of melatonin with the water molecules present in the bloodstream is of fundamental importance in understanding its bioactivity. However, studies of the interaction of melatonin with water molecules are quite limited in the literature. In this sense, the main objective of this work was to study the effects of aqueous solvation on the geometric and electronic parameters of melatonin using the Car-Parrinello Molecular Dynamics. The main effects of aqueous solvation on geometric parameters of melatonin were observed for the bond lengths C14-O2 (2.176%), N17-C14 (2.169%) and N16-H21 (1.079%). The bond angles that were most affected by aqueous solvation were O1-C3-C4 e O1-C3-C8 which an absolute average deviation of 4.37% and 4.241%, respectively. These deviations of the aqueous phase relative to the gas phase are attributed mainly to the formation of to the hydrogen bonding at the O1 site of the methoxy group, O2 and H30 site of the amide group and H21 site of the indole. The topological analyzes confirm the existence of the bond formation between the atoms of the melatonin molecule and the atoms of the water molecules, as well as the degree of covalence and the strength of the interaction. The interactions around the O1, H30 and H21 sites vary from weak to moderate, and only for the O2 site the interactions vary from weak to strong. Therefore, these geometric and electronic changes must be taken into account to explain the bioactivities of melatonin.