Protective effects of ethanolic peel and pulp extracts of Citrus macroptera fruit against isoproterenol-induced myocardial infarction in rats

Increases in the incidence of cardiovascular disease (CVD) have aroused strong interest in identifying antioxidants from natural sources for use in preventive medicine. Citrus macroptera (C. macroptera), commonly known as “Satkara”, is an important herbal and medicinal plant reputed for its antioxidant, nutritious and therapeutic uses. The aim of the present study was to investigate the cardio-protective effects of ethanol extracts of C. macroptera peel and pulp against isoproterenol (ISO)-induced myocardial infarction (MI) in rats. Male albino Wistar rats (n = 36) were pre-treated with peel and pulp extracts (500 mg/kg) for 45 days. They received a challenge with ISO (85 mg/kg) on the 44th and 45th days. Our findings indicated that subcutaneous injection of ISO induced severe myocardial injuries associated with oxidative stress, as confirmed by elevated lipid peroxidation (LPO) and decreased cellular reduced glutathione (GSH) and anti-peroxidative enzymes, including glutathione peroxidase, glutathione reductase and glutathione-S-transferase, compared with levels observed in control animals. Pre-treatment with C. macroptera peel and pulp extracts prior to ISO administration however, significantly improved many of the investigated biochemical parameters, i.e., cardiac troponin I, cardiac marker enzymes, lipid profile and oxidative stress markers. The fruit peel extract showed stronger cardio-protective effects than the pulp extract. The biochemical findings were further confirmed by histopathological examinations. Overall, the increased endogenous antioxidant enzyme activity against heightened oxidative stress in the myocardium is strongly suggestive of the cardio-protective potential of C. macroptera.