Cardioprotective effect of melatonin-standardized ethanol extract of Ulva lactuca L against acute myocardial infarction in rats induced by isoproterenol

Purpose: To investigate the cardioprotective effect of standardized melatonin ethanol extract of Ulva lactuca (smEEUL) against acute myocardial infarction induced by isoproterenol (ISO).
Methods: Male Wistar rats were divided into 6 groups of 6 rats each. Group A was control group given carboxymethylcellulose (CMC Na) while Group B was given ISO 85 mg/kg BW, subcutaneously. Groups C, D and E were given ISO plus smEEUL 250, 500 and 750 mg/kg orally, respectively. Group F was given melatonin 10 mg/kg. Both smEEUL and melatonin were administered for 28 days. ISO was injected twice, i.e., on days 29 and 30. At the end of the study, electrocardiogram (ECG) was recorded, and blood samples collected for myocardial necrosis enzyme assay. Macroscopic features of left ventricle of the heart were also examined using triphenyl tetrazolium chloride (TTC) staining
Results: ISO-treated group demonstrated a significant (p < 0.05) elevation in the level of creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST), with increase of 64.01, 65.66 and 99.40 %, respectively, compared with control group. ECG pattern from ISO also showed ST segment elevation. The groups given smEEUL reduced significantly the level of CK, LDH and ST segment elevation (p < 0.05). The highest dose showed a reduction (p < 0.05 of 62.52 and 77.70 % in the levels of CK and LDH, respectively, compared with ISO treated group. Macroscopic examination y using TTC staining supported the above results.
Conclusion: The results show that administration of smEEUL produces cardioprotective effect by restoring ST segment elevation, and reducing both the area of myocardial infarction and myocardial necrosis enzyme level.

Keywords
Cardioprotective; Ulva lactuca L; Isoproterenol; Melatonin; Myocardial necrosis and infarction; ST segment