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 (500mg/kg) for 45days. They received a challenge with ISO (85mg/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.
The study was designed to evaluate the cardioprotective effects of the standardized aqueous and 80% ethanol extracts of Labisia pumila var. alata (LPva) in isoproterenol (ISO)-induced myocardial infarction (MI) in rats. The extracts were administered to Wistar rats orally for 28 days with three doses (100, 200 and 400 mg/kg of body weight) prior to ISO (85 mg/kg)-induced MI in two doses on day 29 and 30. The sera and hearts were collected for biochemical and histopathological analysis after the rats were sacrificed 48 h after the first induction. The main components of the extracts, gallic acid, alkylresorcinols and flavonoids were identified and quantitatively analyzed in the extracts by using a validated reversed phase HPLC method. The extracts showed significant protective effects as pretreated rats showed a significant dose-dependent decrease (p < 0.05) in cardiac enzyme activities, i.e., cardiac troponin I (cTnI), creatine kinase MB isoenzyme (CK-MB), lactate dehydrogenase (LDH), alanine transaminase (ALT) and aspartate transaminase (AST), when compared with ISO-control rats. There were significant rises (p < 0.05) in the activity of oxidase enzymes, i.e., glutathione peroxide (GPx), catalase (CAT) and superoxide dismutase (SOD) of the pretreated rats, when compared with ISO-control group. Histopathological examination showed an improvement in membrane cell integrity in pre-treated rats compared to untreated rats. The major components of LPva extracts can be used as their biomarkers and contributed to the cardioprotective effects against ISO-induced MI rats.