The term flavonoid describes all polyphenolic plant constituents that have a carbon skeleton analogous to that of the flavones -that is, two substituted benzene rings connected a 3-carbon chain. All of the approximately 4000 flavonoids that have been identified possess this same basic structural makeup. They are nearly ubiquitous secondary metabolites found especially in leafs, fruits & flowers. The are water soluble and occur both in free state and as glycosides.
Their molecular classification can be broken down as follows:
Their major role in plants is to function as growth regulators, and protect the plant from UV radiation by scavenging free radicals produced by the photosynthetic electron transport system. The also act as pigments, imparting colour to flowers & fruits.
Major Flavonoids Classes Include:
In the body they have a wide range of actions and many medicinal uses. Being potent antioxidants, they have been referred to as “nature’s biological response modifiers” or Redox Regulators, since they modify the body’s reaction to compounds such as allergens, viruses and carcinogens as evidenced by their anti-inflammatory, anti-allergic, antiviral and anticancer properties. Additionally they will strengthen vascular capillaries to prevent leakage of body fluids into surrounding tissues, and some will have phytoestrogenic, and liver-protective activity.
In summary the major actions of flavonoids include:
Pharmacology of Flavonoids