or bioflavonoids, isoflavonoids, derived from 3-phenylchromen-4-one (3-phenyl-1,4-benzopyrone) structure, and neoflavonoids, derived from 4-phenylcoumarin (4-phenyl-1,2-benzopyrone) structure.

As ketone-containing compounds, the three flavonoid classes are grouped as anthoxanthins (flavones