Redox reactions of heme proteins with flavonoids

Proteins containing heme groups perform a variety of important functions in living organisms. The heme groups are involved in catalyzing oxidation/reduction reactions, in electron transfer, and in binding small molecules, like oxygen or nitric oxide. Flavonoids, low molecular weight plant polyphenols, are ubiquitous components of human diet. They are also components of many plant extracts used in herbal medicine as well as of food supplements. Due to their relatively low reduction potential, flavonoids are prone to oxidation. This paper provides a review of redox reactions of various heme proteins, including catalase, some peroxidases, cytochrome P450, cytochrome c, myoglobin, and hemoglobin with flavonoids. Potential biological significance of these reactions is discussed, in particular when flavonoids are delivered to the body at pharmacological doses.