Efeitos contráteis, elétricos e antioxidantes de Canavalia rosea no miocárdio de rato e seu papel na prevenção dos danos decorrentes da lesão provocada pela reperfusão tissular ; Contractile, electrical, and antioxidant effects produced by canavalia rosea on the rat myocardium and evauation of its role preventing injuries caused by reperfusion of the cardiac tissue

Plant-derived products have been widely studied for prevention and treatment of several diseases. Substances present in them showing antioxidant activities are of great interest because they are able to minimize cardiac injury associated to reperfusion of ischemic tissues. The cardiac reperfusion injury is a physiopathological phenomenon that can occur in coronary syndromes, during cardiovascular surgery and during angioplasty generating heart tissue lesions. In this context, it becomes important to evaluate the biological effects promoted by plant extracts looking for understand their potential for antioxidant protection in order to prevent cardiac tissue damage. Ethyl acetate fraction (FAE) was obtained from the crude extract of Canavalia rosea leaf. FAE was subjected to a phytochemical screening and some antioxidants molecules were identified. Quantitative evaluation of the antioxidant activity and the ability of FAE to scavenge DPPH radicals was performed. It was found that FAE caused a significant reduction in the amount of this radical (p < 0.001), inhibiting its production in 46.7 ± 3.5% with a EC50 of 20.9 ± 0.3 μg/mL. The index of antioxidant activity (IAA) associated to this fraction was 1.42, considered high (Soler-Rivas et al., 2000; Argolo et al., 2004). The in vitro lipid peroxidation was induced by ferrous sulfate. Different concentrations of FAE reduced the lipid peroxidation induced by this substance. We also have evaluate the electrical and contractile effects of FAE (300 μg/mL) in isolated hearts of rats mounted in Langendorff aortic perfusion system. FAE changed significantly, the electrocardiographic profile, increasing the duration of the following intervals: PRi (from 78.48 to 104.7, n = 5, p<0.05), QTi, (from 30.41 to 41.03, n = 5, p<0.05) as well as the QRS complex (from 17.36 to 25.19, n = 5, p<0.05). Furthermore, it reduced the heart rate (from 128.5 to 87.8, n =5, p<0.05). Studing its contractile effects, we have observed that this fraction promoted reduction of the ...