Can hydroxylate xanthotoxin (8-methoxypsoralen) to form 5-hydroxyxanthotoxin (5-hydroxy-8-methoxypsoralen) in vivo and in vitro (PubMed:18291319). Involved in the early iron deficiency response, possibly through an IDE1-like mediated pathway (PubMed:21315474). Involved in the pathway of sideretin biosynthesis from feruloyl CoA, a redox-active catecholic metabolite exuded by roots in response to iron deficiency in order to facilitate the uptake of iron; this pathway consists in the successive conversion from feruloyl CoA to scopoletin, from scopoletin to fraxetin and from fraxetin to sideretin (PubMed:29581584). Catalyzes the biosynthesis of sideretin via fraxetin hydroxylation (PubMed:29581584). fraxetin + O2 + reduced [NADPH--hemoprotein reductase] = H(+) + H2O + oxidized [NADPH--hemoprotein reductase] + sideretin (reduced form) O2 + reduced [NADPH--hemoprotein reductase] + xanthotoxin = 5-hydroxyxanthotoxin + 2 H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Phenylpropanoid metabolism. Expressed in both primary and lateral roots under iron-deficient conditions, except in apical root zones, and mostly in the root epidermal layer. By iron deficiency, mainly in roots. Increased root length at seedling stage (PubMed:21315474). Accumulation of fraxetin, but loss of sideretin root secretion in response to iron deficiency. Slightly increased iron-uptake ability at elevated pH leading to a better fitness of plants, due to the presence of high fraxetin content (PubMed:29581584). Plants overexpressing CYP82C4, can hydroxylate and subsequently glycosylate 8-methoxypsoralen. Belongs to the cytochrome P450 family.