Pharmacological Evaluation of Emodine Against Isoproterenol-Induced Cardiac Hypertrophy

Cardiovascular diseases continue to represent a major global health burden, accounting for approximately one-third of worldwide mortality. Myocardial infarction results from prolonged ischemia leading to irreversible myocardial necrosis and subsequent structural and functional impairment. Oxidative stress, inflammation, calcium overload, and membrane lipid peroxidation contribute significantly to myocardial injury.

Isoproterenol-induced myocardial infarction is a widely accepted experimental model that closely resembles several pathological features of human myocardial infarction. Excessive β-adrenergic stimulation causes oxidative damage, calcium overload, mitochondrial dysfunction, and myocardial necrosis.

Natural products have emerged as promising therapeutic agents due to their multitarget pharmacological activities. Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a bioactive constituent found in Rheum species and Polygonaceae plants. Previous investigations have demonstrated antioxidant, anti-inflammatory, anti-apoptotic, and cardioprotective activities of Emodin. However, comprehensive evaluation against isoproterenol-induced myocardial infarction remains limited.

The present study investigated the cardioprotective potential of Emodin in an experimental rat model of myocardial infarction using functional, biochemical, and histopathological endpoints.

MATERIALS AND METHODS

Experimental Animals

Adult Sprague-Dawley rats weighing 180–220 g were maintained under standard laboratory conditions with free access to food and water. Experimental procedures were approved by the Institutional Animal Ethics Committee and conducted according to CPCSEA guidelines.

Experimental Design

Animals were divided into six groups:

Group I: Normal Control

Group II: Vehicle Control (ISO 100 mg/kg)

Group III: Metoprolol (10 mg/kg + ISO)

Group IV: Emodin (20 mg/kg + ISO)

Group V: Emodin (40 mg/kg + ISO)

Group VI: Emodin (80 mg/kg + ISO)

Emodin and metoprolol were administered orally for 30 consecutive days. Isoproterenol (100 mg/kg, i.p.) was injected on days 29 and 30.

Assessment Parameters

1. Body Weight and Heart Weight
2. Electrocardiography (Heart Rate, RR, QRS, QT, QTc, PR, ST)
3. Hemodynamics (SBP, DBP, MABP)
4. Serum Cardiac Biomarkers (CK-MB, LDH, ALP)
5. Antioxidant Parameters (MDA, GSH, SOD, Nitric Oxide)
6. Histopathological Examination

Statistical Analysis

Data were analyzed using one-way ANOVA followed by Dunnett’s multiple comparison test. P < 0.05 was considered statistically significant.

Methods: Myocardial infarction was induced using isoproterenol (100 mg/kg, i.p.) administered on days 29 and 30. Rats were pretreated orally with Emodin (20, 40, and 80 mg/kg) or Metoprolol (10 mg/kg) for 30 days. Electrocardiographic parameters, hemodynamic measurements, cardiac weight indices, serum cardiac biomarkers, oxidative stress markers, and histopathological alterations were assessed.

 

 

Image No. 1 Plan of Work Chart

 

 

Effect of isoproterenol on histopathological alteration in cardiac tissue

DISCUSSION

The present investigation demonstrates significant cardioprotective effects of Emodin against isoproterenol-induced myocardial injury. The observed increase in cardiac weight following isoproterenol administration indicates myocardial edema and hypertrophy resulting from oxidative stress and inflammatory processes.

ECG abnormalities observed in vehicle control animals are characteristic features of myocardial infarction and reflect impaired cardiac conduction and ventricular dysfunction. Emodin treatment markedly corrected these abnormalities, suggesting stabilization of myocardial membranes and preservation of electrical activity.

The restoration of blood pressure parameters indicates improved myocardial contractility and hemodynamic stability. Previous studies have attributed these beneficial effects to the antioxidant and anti-inflammatory properties of Emodin.

The cardioprotective effects are likely mediated through reduction of oxidative stress, inhibition of lipid peroxidation, enhancement of endogenous antioxidant defenses, and preservation of myocardial cellular architecture.

CONCLUSION

Emodin demonstrated significant dose-dependent cardioprotective activity against isoproterenol-induced myocardial infarction. The highest tested dose (80 mg/kg) exhibited efficacy comparable to metoprolol in improving electrocardiographic, hemodynamic, and cardiac weight parameters. These findings support the therapeutic potential of Emodin as a promising cardioprotective agent and warrant further mechanistic and clinical investigations.

Ethical Approval

The study was approved by the Institutional Animal Ethics Committee and conducted according to CPCSEA guidelines.

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