Preservation of mitochondrial structure and function by the cocoa flavanol Epicatechin

Studies have linked high-flavanoid rich diets with improved cardiovascular health. Cocoa contains large amounts of flavanoids, particularly the subtype known as flavanols, and has been shown to possess cardioprotective properties. Studies have linked the cardioprotective effects of cocoa to epicatechin (epi), a flavanol in chocolate. One study looked at the effects of epi in the setting of myocardial ischemia-reperfusion (IR) injury. In this study, epi was administered to rats 10 days before an (IR) event. The results comparatively demonstrated a 25% decrease in infarct size in epi treated animals to the control. Another study was implemented to determine if epi still provided cardioprotection when administered prior to reperfusion. Results showed that epi protects the heart when administered before reperfusion. We wish to study the mechanism by which epicatechin exerts these cardioprotective effects. The extent to which cardiac tissue survive IR injury depends on the viability of the mitochondria. We hypothesize that the cardioprotective effects of epicatechin are mediated through protection and enhancement of mitochondrial structure and function. To test this mitochondria was isolated from three subject groups: sham, IR and IR + epi and mitochondrial respiration and calcium levels were evaluated. Animal tissue from a subgroup was saved and processed for electron microscopy. Results showed a decrease in respiration and an increase in intramitochondrial Ca²⁺ levels in the IR group. Both these levels indicate a decrease in mitochondrial viability. In conclusion, the results suggest that epicatechin protects the heart against IR injury by promoting mitochondrial respiration and preventing calcium overload.