Scheme 1

Cyclophosphamide converted by MroUPO to human drug metabolites. MroUPO transformed of cyclophosphamide (CPA) into the intrinsic active metabolite 4-hydroxy-cyclophsophamide (4-OH-CPA), its tautomer aldophosphamide (APA) and the overoxidized side product 4-ketocyclophsophamide (4-keto-CPA)