ABSTRACT

Coronary artery disease, and its end results myocardial infarction, is a significant cause of morbidity and mortality globally. Recently, there has been an increase in the incidence of myocardial infarction which manifests as a result of disrupted blood supply and oxygen to the myocardium. This present study evaluated the effect of methanol leaf extract of Jatropha tanjorensis on some cardiac function biomarkers in isoprenaline-induced myocardial infarction in albino rats. The in vitro qualitative phytochemical and antioxidant properties of Jatropha tanjorensis leaves were determined using standard analytical methods. Thirty six (36) albino rats were used for the in vivo study and randomly divided into six (6) groups of six rats per group. Group 1 served as the normal control, group 2 was the negative control (administered 85mg/kg of isoprenaline only), group 3 served as the positive control (pretreated with 2mg/kg carvedilol for 28 days), groups 4, 5 and 6 were pretreated with 200, 400 and 600mg/kg of methanol leaf extract of Jatropha tanjorensis respectively, for 28 days. Myocardial infarction was induced in the rats using subcutaneous injection of 85mg/kg isoprenaline (ISO) for two consecutive days (26^th and 27^th) at 24 hours intervals. The in vitro phytochemical and antioxidant results revealed that Jatropha tanjorensis leaves possess good bioactive compounds such as alkaloids, terpenoids, flavonoids, steroids, tannins, saponins, phenolics and free radical scavenging potency. The acute toxicity study of the extract recorded no death even at the high dose of 5000mg/kg. The result of the in vivo study showed that isoprenaline effectively induced myocardial infarction in rats, reflected by the  significant (p<0.05) increases, in the negative control group, of the measured biomarkers  (Creatine Kinase-MB activity, Troponin I activity, Lactate Dehydrogenase acitivity, Aspartate aminotransferase activity, Alanine aminotransferase activity, high sensitivity C-Reacting Protein concentration, Triacyglycerol concentration, Cholesterol concentration and Malondialdehyde concentration) relative to the normal control. The extract (400mg/kg) significantly (p<0.05) decrease CK-MB activity, Troponin I activity, LDH acitivity, AST activity, ALT activity, hsCRP concentration, TAG concentration, Cholesterol concentration, and MDA concentration while increasing HDL concentration, catalase activity, SOD activity, GPx activity and GSH concentration. The histopathological study showed different degrees of cardiac alteration. There was marked histomorphological alteration, severe widespread myocardial necrosis of the heart, atrophy of hepatic cord but mild multifocal vascuole degeneration of the renal tubular epithelial lining cell in the group administered 600mg/kg of the extract and the negative control compared to the normal control. This indicated that the extract at 600mg/kg dose does not possess cardioprotective potency. The carvedilol at 2mg/kg dose showed moderate potency in restoring damage cells. The methanol leaf extract of Jatropha tanjorensis at moderate dose (400mg/kg) attenuated the effect of isoprenaline-induced myocardila damage without alteration of the liver and kidney. This study suggested that the extract to some extent could serve as an agent for the prevention of cardiotoxicity.