CHAPTER ONE

INTRODUCTION 1.1 Theobroma cacao 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. Bioactive compounds from plant sources such as phenolics have gained substantial interest in recent years owing to their unique functions and nutritional values including antioxidant, antimicrobial, antimutagenic and antitumor activities (Nsor-Atindana et al., 2012). Cocoa is rich in flavonoids which protect against cardiovascular diseases through their antioxidant, antiplatelet, and anti-inflammatory effects. Flavonoids may also lower blood pressure, increase high density lipoprotein cholesterol, positively modify insulin sensitivity and improve endothelial function (Agarwal, 2013). Cocoa and cocoa derivatives are recognized as major dietary source of antioxidants because of their high phenolic (procyanidins and flavanols mainly) content (Tomas-Barberan et al., 2007). Several groups of polyphenols are found in fruits, whereas the most important are the flavanols which can be further subdivided into the monomers epicatechin and catechin (Arts et al., 2000) and their dimers, oligomers and polymers, the so-called procyanidins (Lazarus et al., 1999; Adamson et al., 1999) responsible for the bitterness of cacao, through the formation of the complexes with salivary proteins (Manach et al., 2004). Numerous dietary intervention studies in humans and animals indicate that flavanol-rich foods and beverages exert cardioprotective effects with respect to vascular function and platelet reactivity (Carl et al., 2005). The consumption of flavanol-rich cocoa has been reported to improve endothelial function (Wang-Polagruto et al., 2006) and reduce the incidence of atherosclerotic diseases (McCullough et al., 2006). Cardiovascular disease (CVD) is one of the main causes of death worldwide and most common in industrial societies (Chiva-Blanch et al., 2013). It is developed by a multifactorial process. Most CVDs are due to atherosclerosis, a degenerative process of the arteries that is induced by oxidative stress and chronic inflammatory status. The risk factors of this disease are smoking, diabetes mellitus, arterial hypertension, abnormalities in serum levels of total cholesterol and its fractions, overweight/obesity, family history of early CVD and physical inactivity, amongst others (Chiva-Blanch et al., 2013). Myocardial infarction is the acute condition of necrosis of the myocardium that occurs as a result of imbalance between coronary blood supply and myocardial demand (Boudina et al., 2002). Ischemic tissues generate oxygen derived free radicals which have been implicated in cardiac diseases and metabolic disorder (Prabhu et al., 2006). The model of isoproterenol-induced myocardial ischemia is considered as one of the most widely used experimental model to study the beneficial effects of many drugs on cardiac function (Grimm et al., 1998). The pathophysiological changes following isoproterenol administration are comparable to those taking place in human myocardial ischemia/infarction (Wexler, 1978). Increases in the formation of reactive oxygen species during ischemia/reperfusion and the adverse effects of oxyradicals on myocardium have been well established by both direct and indirect measurements (Wexler, 1978). Many epidemiological studies associate an increased consumption of foods and beverages rich in flavonoids, with a reduced risk of cardiovascular death (Kris-Etherton and Keen, 2002).

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