The Effect of Ethanol Extract of Theobromacacao Polyphenol on Isoproterenol-Induced Myocardial Infarction in Wistar Rats.


This study investigated the effect of cocoa polyphenol on isoproterenol-induced myocardial infarction in Wistar rats. Polyphenol was extracted from cocoa using a hydroalcohol solvent.

Forty albino rats divided into six groups of four rats each were used for the study. Groups 3, 4, 5 and 6 were pretreated with the extract (300, 500 and 700 mg/kg) and 100 mg/kg of atenolol (standard drug) respectively before administration with isoproterenol.

Group 1 served as normal control while  group  2 was administered with isoproterenol without any treatment.

The activities of marker enzymes such as aspartate amino transferase (AST), alanine amino transferase (ALT) and lactate dehydrogenase (LDH) in both serum and heart tissue homogenate were assayed and serum concentrations of total cholesterol, LDL-cholesterol, HDL- cholesterol, triglycerides and malondialdehyde (MDA) were  used  to  determine success of isoproterenol induction and response to treatment.

Enzyme assays carried  out on the serum and  heart tissue homogenates showed  increased activities in the serum and low activities in the heart homogenate in the untreated group when  compared to the normal control.

Histological studies carried out on the heart tissues revealed marked degeneration of the myocardium in the  untreated  group  and  in groups that received lower concentrations (300 and 500 mg/kg) of the cocoa extract.

This corresponded with increased activities of the marker enzymes in the serum and  low activities in the heart homogenate in these same groups.

However, almost a total cardioprotection was observed in the group that  received  700 mg/kg extract as revealed by the activities of marker enzymes in serum and heart tissue homogenate, concentrations of lipid profile parameters, level of lipid peroxide product and histological observations that showed heart tissue morphology very similar to that of  the normal group.

The results showed that consumption of cocoa as a functional food could reduce the risk of cardiovascular diseases and improve treatment outcomes.


Background Of Study

Cocoa (Theobroma cacao) is a major economic tree crop in Nigeria (Alamu, 2013). T. cacao grows in the subtropical areas of the world.

Although it grows widely from the southeastern Mexico to the Amazon basin, two thirds of the world’s production comes from four West African countries, the Ivory Coast, Ghana, Nigeria and Cameroon.  Ivory Coast is the world’s largest exporter of cocoa (Agarwal, 2013).

The cocoa tree produces ‘cauliflory’ flowers in clusters directly on the trunk  and  older  branches. After pollination, ‘cacao pod’ fruits are produced.

Each pod contains about 20 to 60 seeds, called “cocoa beans”, embedded in a white pulp. These cocoa beans were considered divine by the Mayans, as they were presumably discovered by the god Quetzalcoatl.

They believed that cocoa beans make one strong and invincible.  Spaniards noted that cocoa consumption allowed the Aztecs greater stamina and they could walk long distances without fatigue.

The Olmec, Mayan and  some  Mexican tribes also recognized the medicinal value of these beans (Agarwal, 2013). Cocoa products have been enjoyed by humans for centuries.

Chocolate is made from cocoa (Theobroma cacao). Consumed world over for its pleasant taste and its pleasurable and stimulating effects, epidemiological and scientific studies have repeatedly demonstrated significant health benefits with its intake.

Kuna Indians living on Panama’s San Blas Islands drink more than four cups of cocoa per week and rarely develop age-related high blood pressure or heart disease.


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