Iodine heterocycles: [125I] and [131I] ortho-iodosophenylphosphoric acid

Since organic molecules tagged with radioiodine are often subject to dehalogenation, techniques are needed for "protecting" the iodine. A suggested approach was the incorporation of iodine directly into a heterocyclic compound as one of the ring's heteroatoms. Such a compound, orthoiodosophenylphosphoric acid, was synthesized with I-125 and I-131. Upon i.v. administration to dogs and rabbits, most of the radiolabel was excreted in the urine. There was no evidence of the appearance of free iodide. The renal elimination of orthoiodosophenylphosphoric acid was contrasted with the biliary excretion of another iodine heterocycle, diphenyleneiodonium. Iodine heterocycles, with appropriate substituents, may represent a useful class of compounds for biologic studies.