Flavonas

Flavonas, commonly known as flavones, are a class of flavonoids, a large group of polyphenolic compounds produced by plants. They share a characteristic chemical core: a 2-phenyl-1-benzopyran-4-one skeleton, consisting of two benzene rings (A and B) fused to a heterocyclic C ring. Variation in hydroxyl and methoxy substitutions gives numerous flavone compounds. Notable examples include apigenin, luteolin, chrysin, and diosmetin.

Natural occurrence and sources are broad; flavones are found in many fruits, vegetables, herbs, and beverages. Parsley, celery, chamomile, onions, and citrus fruits are commonly cited sources. In plants they often occur as glycosides (flavone molecules bound to sugar moieties), and can be hydrolyzed to yield the aglycone forms.

Biosynthesis of flavones proceeds via the plant flavonoid pathway. Phenylalanine-derived precursors are converted through a series of enzymes, including chalcone synthase and flavone synthase, to yield flavone structures such as apigenin and luteolin. Glycosylation and methylation further diversify the naturally occurring forms.

Biological activities studied for flavones include antioxidant and anti-inflammatory effects, modulation of enzymes and signaling pathways, and potential anticancer properties in laboratory and animal studies. Clinical evidence in humans is limited and results are not yet conclusive. Bioavailability depends on the form ingested (glycosides vs aglycones) and metabolic transformation after absorption. Overall, flavones are recognized for their prevalence in the diet and their wide range of biological activities, though more research is needed to clarify their health effects.