 Finally, a flavanone synthase (FNS) enzyme oxidizes naringenin to apigenin.Two types of FNS have previously been described; FNS I, a soluble enzyme that uses 2-oxogluturate, Fe2+, and ascorbate as cofactors and FNS II, a membrane bound, NADPH dependent cytochrome p450 monooxygenase.The naturally occurring glycosides formed by the combination of apigenin with sugars include