Plant secondary metabolites, derived from 2-phenylchromen-4-one structure, flavonoids are pigment (or co-pigment) for plants, protecting them from UV-radiation, free-radical scavengers, attracting pollinator animals. They have potential salutary effects on human health, but there is no physiological evidence established today. In vitro, they are enzymatic inhibitors and have anti-cancer, anti-allergic, anti-inflammatory and anti-microbial activities.