Estudo do efeito vascular de um novo complexo de rutênio em aorta de ratos

Abstract

Cardiovascular diseases (CVD) represent a significant challenge in public health, being the main cause of death in Brazil. Often the development of these diseases is associated with endothelial dysfunction caused by a decrease or imbalance in the release of nitric oxide (NO). Ruthenium complexes have been the subject of intense investigations due to their ability to release NO. In view of this, the search for new compounds that have the ability to act by modulating the relaxing response of blood vessels is extremely important for the development of therapeutic strategies aimed at the prevention and treatment of cardiovascular pathophysiology. Therefore, the work aimed to study the vascular effect of the new ruthenium complex [Ru(bpy)2(Bzim)NO](PF6)3 (FOR0803), in an ex vivo methodology, and in silico through molecular docking. The project was approved by CEUA/NPDM under protocol nº 30051221-0. In vascular reactivity assays, the ex vivo isolated organ bath methodology was used, where the aorta artery segments of rats with intact or denuded endothelium were pre-contracted with potassium chloride (KCl 60 mmol/L) (n=6) or with phenylephrine (PHE, 1 µmol/L) (n=6) with subsequent performance of a cumulative concentration-effect curve with FOR0803 (3.16-10 to 10-5 M). To characterize the mechanism of action, a pre-incubation was carried out with the inhibitors ODQ, L-NAME, Wortmannin, Hydroxocobalamin and L-cysteine, to study the participation of the nitric oxide pathways (NO/GCs/cGMP) and with Tetraethylammonium, 4-aminopyridine, and Glibenclamide, to study the potassium channel pathways. In descriptive statistics, statistical differences between two groups were analyzed using Student's t test for independent samples, for comparisons of three or more groups, ANOVA was used, associated with Dunnett's or Tukey's multiple comparisons test, considering statistically significant values of p<0.05. Data were analyzed and graphs were constructed using the statistical software GraphPad® Prism v 8.0. For in silico analysis, molecular docking simulations were carried out. The results showed that FOR0803 had a greater vasorelaxant effect in aortic rings pre-contracted with phenylephrine compared to the control, however in preparations pre-contracted with potassium chloride the compound demonstrated a reduction in this effect. Furthermore, the results demonstrated that the vasorelaxant effect of FOR0803 was independent of endothelium. When pre-incubated with the inhibitors ODQ and Hydroxocobalamin, the compound had its vasorelaxant effect abolished, demonstrating a significant loss in its potency and effectiveness, and when pre-incubated with the other inhibitors L-NAME, Wortmannin, L-cysteine, TEA, 4-AP, and Glibenclamide showed a significant loss of potency. These findings indicate that the main vasorelaxant effect occurs via stimulation of the enzyme soluble guanylate cyclase (GCs) and NO donation, and may also act partially through underlying pathways. Molecular docking showed that the interaction of FOR0803 with GCs presented acceptable affinity data (below -6.0 kcal/mol) capable of firmly binding with the target macromolecules. It is concluded that FOR0803 is a possible NO donor and activator of the NO/GCs pathway, and acts partially on K+ channels.