Cardioprotective effects of different flavonoids against myocardial ischaemia/reperfusion injury in Langendorff-perfused rat hearts

Objective Flavonoids are important components of functional foods', with beneficial effects on the cardiovascular function, mainly due to their antioxidant activity. Many flavonoids exert antihypertensive, anti-atherosclerotic and antiplatelet activity and positive effects against endothelial dysfunction. Recent evidence indicates that they exert cardioprotective effects against myocardial ischaemia/reperfusion (I/R) injury. The aim of this work was to investigate these properties for flavonoids with different structural characteristics. Methods In this work, the cardioprotective effects of eight flavonoids endowed with different structural characteristics were tested on Langendorff-perfused rat hearts submitted to 30min of global ischaemia followed by 120min of reperfusion (I/R). Key findings Only the 5-hydroxy-substituted derivatives, such as 5-hydroxy flavone, apigenin, chrysin and naringenin, conferred on the hearts an improved post-ischaemic functional recovery associated with lower extension of tissue injury. A similar pharmacological profile was exhibited by 5-methoxy flavone. In contrast, 6-hydroxy flavone, 7-hydroxy flavone and 4-hydroxy flavanone did not confer significant protection against the injury induced by I/R. Conclusions Some flavonoids exhibit direct cardioprotective effects against the injury induced by drastic I/R and this pharmacological property seems to be related to their structural characteristics. Such an influence of structural requirements seems to indicate that the cardioprotective effects may be due to the interaction with specific pharmacological targets.