Flavonoids in Our Foods: A Short Review

The aerobic metabolism in biological systems, produces reactive oxygen species (ROS) known as prooxidants even in basal conditions. If the formation of prooxidants increases, it leads to oxidative stress/damage. Various diseases in humans (cancer, chronic diseases, cardiovascular problems etc.) accompanies with prooxidant damage. Endogenous and exogenous antioxidants protect biomolecules against the damage of prooxidants. Flavonoids are potent antioxidant molecules, which scavenge free radicals in vitro. They are found in fruits, vegetables, bark, roots, flowers and certain beverages. It has been reported that these natural products produce a wide variety of biological effects, like antiviral, anti-allergic, anti-inflammatory, anti-carcinogenic, antidiabetic effects. Flavonoids are important for human diet and have beneficial effects on health like chelating trace elements involved in free radical production, scavenging ROS and upregulating or protecting antioxidant defenses. In addition, they have known to modulate different cytochrome P450 enzymes such as CYP1A1/1A2, CYP1B1, CYP2C9, and CYP3A4/3A5. Flavonoids and their metabolites in organism may cause flavonoid-drug interaction, and it may lead to toxicity of drug or inefficient therapeutic effects of drug. However, knowledge on the mechanisms of action of flavonoids is still not fully understood. The information about correlation of structure-biological effect is limited. There are six major subclasses of flavonoids are flavanols, flavanones, flavonols, flavones, anthocyanidins, and isoflavones. This review summarizes the types of flavonoids, possible mechanisms of action and pharmacokinetic specialties, bioavailability, properties and drug interactions of these flavonoids.