Estudo das propriedades estruturais da curcumina no vácuo usando dinâmica molecular de Car-parrinello

Abstract

Curcumin is a yellow-orange pigment extracted from the rhizomes of the plant Curcuma longa L., metoxifenois comprises two rings, in conjunction symmetrically connected by β - diketone moiety and has a keto-enol tautomerism. Has been highlighted by presenting a broad therapeutic potential, with antibacterial, anti-inflammatory, antioxidant, proapoptotic, chemopreventive, anticarcinogenic and others. Despite the diverse biological properties identified, there are few theoretical studies on this drug candidate. A theoretical study, especially on the structural properties, is critical to the initial understanding of the relationship between structure and biological activity of a potential drug. In this sense, the present work aimed to study the structural properties of the isomers of curcumin plans in a vacuum, using the method of molecular dynamics Car-Parrinello. For the calculations, each isomer was located in a cubic box with dimensions of 23 Å to form keto and 27 Å for the enol form. The energy functional exchange-correlation functional was modeled using the gradient corrected PBE. The core electrons were treated with pseudopotentials ultrasolf Vanderbilt, and valence were represented by the set of basis functions in plane waves, truncated into kinetic energy cutoff of 20 Ry . DMCP simulations were performed at 300 K with an integration step of 6,0 a.tu. and fictitious mass of 500 a.u. The results show a good agreement with the structural properties of curcumin determined by other methods. In comparing the isomers, we identified a great similarity between the values of bond lengths keto form and enol form as well as the bond angles. The dynamics of the proton transfer in the intramolecular O–H∙∙∙O to the enol form of curcumin, characterized by interactions of short duration and high frequency switch. This study contributes to the understanding of structural isomers of curcumin plans, as well as the proton transfer in the intramolecular hydrogen bond, identified in the enol form.