Catalyzes the 3'-hydroxylation of the flavonoid B-ring to the 3',4'-hydroxylated state (PubMed:18726614). Catalyzes the 3'-hydroxylation of apigenin to generate luteolin (Probable). a 3'-unsubstituted flavone + O2 + reduced [NADPH--hemoprotein reductase] = a 3'-hydroxyflavone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Secondary metabolite biosynthesis; flavonoid biosynthesis. Induced by light. Belongs to the cytochrome P450 family.