Polyalthia Longifolia Ameliorates Isoprenaline-Induced Myocardial Toxicity via Markers of Oxidative Stress and Inflammation in Wistar Rats

Cardiovascular disease conditions, such as myocardial infarction (MI), are prominent contributors to global mortality. Isoprenaline induces acute myocardial damage and infarction. Polyalthia longifolia (PL), has been reported to possess various potential health benefits. Thus, this study evaluated the protective role of the phenol-rich fraction of PL leaf on isoprenaline (ISO)-mediated myocardial infarction in rats. Forty male Wistar rats (265±15g) were randomly and equally grouped into five (n=8). Group A (control) received I mL/kg distilled water, B: ISO at 90 mg/kg, C: vitamin C (Vit C) at 100 mg/kg and ISO, and D and E: PL at 100 mg/kg and 200 mg/kg, respectively and ISO. Treatment was done orally and lasted for 13 consecutive days except for ISO which was given subcutaneously on the 13th day. Blood pressure was monitored following acclimatisation. The whole blood and the heart tissue were collected and analysed for antioxidants, inflammation, oxidative stress markers, and histopathology. Isoprenaline increased blood pressure parameters in group B. These parameters were reversed in Vit-C and PL-exposed groups. Isoprenaline significantly (p<0.05) induced oxidative stress and inflammation, and reduced antioxidant markers in group B. Vit C and PLameliorated the isoprenaline-induced toxicity in groups C, D, and E. ISO induced inflammatory cells, infarction, and oedema in the heart tissue in group B. These changes were mildly reversed in Vit-C and PL-treated rats. In conclusion, Polyalthia longifolia phenol-rich fraction mitigated isoprenaline-induced myocardial toxicity in rats, demonstrating effects comparable to those of Vitamin C.