Efeito cardioprotetor do timol em corações de ratos submetidos à lesão de isquemia e reperfusão

Abstract

Acute myocardial infarction occurs when there is reduced blood supply to the myocardium promoting decrease of oxygen uptake (O2). It is a major cause of morbidity and mortality worldwide. Tissue injury occurs, for the most part, paradoxically, during reperfusion of the organ. In reoxygenation, there are exacerbated production of reactive oxygen species (ROS) and intracellular calcium overload, which trigger cell death. There are few pharmacological intervention strategies for the prevention and limitation of these lesions. And besides, the available forms of action are not entirely effective. Recently, it has directed attention to the effects of natural products in limiting the damage caused by ischemia and reperfusion (I/R). In this context, thymol, a phenolic monoterpene, has, among its biological activities, anti-inflammatory and antioxidant. In this sense, the objective of the study was to evaluate the potential cardioprotective effect of thymol in preventing reperfusion injury after ischemia in rats. First it performed the test clearance of radical DPPH by thymol. To study its potential cardioprotective, rats Wistar rats (200-300 g) pretreated with thymol (7.5 mg/kg, v.o.) or vehicle for 7 days and subjected to global ischemia of the heart in the Langendorff system. We evaluated parameters of cardiac function as left ventricle developed pressure (LVDP), maximum time derivative (+ dP/dt) and minimum (-dp/dt) and arrhythmia severity index (ASI), size of the infarcted area, and enzymatic activity assays catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and reductase (GR), tissue sulfhydryl quantification. Moreover, the concentration of thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides evaluated too. The DPPH assay showed antioxidant property of thymol. Furthermore, it was observed that pretreatment with thymol preserved LVDP, ASI decreased, reduced infarct area, the TBARS and, similarly, was observed lower concentration of hydroperoxides as compared to vehicle. Pretreatment with thymol prevented to reduce the concentration of sulfhydryl groups when compared to vehicle. The activities of SOD, CAT, GPx and GR were reduced significantly in the hearts of animals pretreated with thymol when compared to vehicle. Pretreatment with thymol preserved contractile heart function, reduced damage to cellular components and limited the infarct area. Demonstrating significant cardioprotective effects against I/R.