Involved in linear furanocumarin (psoralen) biosynthesis. Converts marmesin to psoralen. (7S)-marmesin + O2 + reduced [NADPH--hemoprotein reductase] = acetone + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] + psoralen Inhibited by columbianetin. By fungal elicitor extracted from Phytophthora sojae cell wall. Psoralen possesses photocarcinogen properties. It intercalates in double-stranded DNA and cross-links pyrimidine bases under UV-A irradiation. Psoralen is widely used in combination with UV-A radiation to treat a variety of skin disorders like psoriasis or eczema. Belongs to the cytochrome P450 family.