Flavonoids, naturally occuring derivatives of 2-phenyl-benzo-γ-pyrone, are widespread in plants as coloring substances. Apigenin (4',5,7,-trihydroxyflavone (5,7-dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one), molecular formula C₁₅H₁₀O⁵, is a flavonoid present in many fruits and vegetables,