Involved in the biosynthesis of coumarins and furanocoumarins (FCs), natural products required for defense responses against attacks by predators with potential medical and agroindustrial usages such as anticoagulant, rodenticide and artificial vanilla substitutes (PubMed:29971079). Catalyzes the conversion of xanthotoxin into 5-hydroxyxanthotoxin (PubMed:29971079). O2 + reduced [NADPH--hemoprotein reductase] + xanthotoxin = 5-hydroxyxanthotoxin + 2 H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Secondary metabolite biosynthesis. Accumulates in roots after wounding. Belongs to the cytochrome P450 family.