Cardioprotective Activities of Pterocarpus mildbraedii Leaves on Isoproterenol-induced Myocardial Infarction in Rats

The study evaluated the effects of Pterocarpus mildbraedii leaf extracts on myocardial infarction induced by isoproterenol (ISO) in Wistar albino rats with a view to ascertain the value of its use in the management of heart-related diseases. Fresh plant leaves were collected, identified, extracted, fractionated and the aqueous layer partitioned with ethyl acetate. GC-MS was carried out on the ethyl acetate fraction (EAF) and unknown compounds were identified by comparing measured mass spectral data with those in NIST 14 Mass Spectral Library. Twenty-five adult rats were divided into five groups of 5 rats each. Groups I &II were the control groups. Rats in groups III-V were pretreated with 50 mg/kg and 100 mg/kg of EAF and 1.8 mg/kg of propranolol respectively for 21 days. Myocardial infarction was then induced in all the rats (except those in Group I) with the intraperitoneal injection of ISO (85 mg/kg) for 2 days. Afterwards, the rats were sacrificed and blood samples, heart homogenate and samples for histological studies were aseptically collected. Activities of cardiac biomarkers, lipid profile, enzymatic and non-enzymatic antioxidants were evaluated using standard methods. GC-MS analysis showed that the most abundant components of the plant are propionic acid, 2,3-dimethylphenyl ester, catechol, octyl-β-D-glucopyranoside, phenol and n-Hexadecanoic acid. Administration of ISO caused significant elevation of the activities of cardiac biomarkers (troponin-T concentrations, creatine kinase-MB and lactate dehydrogenase) while rats pretreated with EAF had significantly lower levels of the biomarkers. Moreover, alterations in lipid profile, enzymatic and non-enzymatic antioxidants brought about by the administration of ISO were ameliorated. Histological examinations revealed lesser degree of myocardial injury in pre-treated rats.