Tetraiodinated

Tetraiodinated refers to a molecule that contains four iodine atoms incorporated into its structure. The term is used across chemistry and biochemistry to describe compounds in which four iodine substituents have been introduced, typically by electrophilic iodination of aromatic rings or by enzymatic iodination of amino acids.

Formation and examples: In organic synthesis, iodination can be controlled to reach mono-, di-, tri-, or tetraiodination. Reagents such as I2 with oxidants (e.g., hydrogen peroxide, periodate) or hypervalent iodine(III) species facilitate successive iodinations. In biochemistry, iodination occurs in the thyroid gland where thyroid peroxidase catalyzes the incorporation of iodine into tyrosine residues of thyroglobulin, producing diiodotyrosine and eventually tetraiodinated products. The primary hormone thyroxine (T4) is 3,5,3',5'-tetraiodothyronine, containing four iodine atoms, and is produced from coupling of two diiodotyrosine units. Deiodination yields other iodinated forms such as triiodothyronine (T3).

Applications and significance: Tetraiodinated compounds are prominent in medical imaging and nutrition due to the high atomic number of iodine providing radiopacity. Iodinated contrast agents used in radiography frequently contain multiple iodine atoms, sometimes reaching four or more per molecule. Tetraiodinated ligands and radiotracers are studied for diagnostic and therapeutic uses, though safety concerns with iodine load and thyroid function are considered in clinical contexts.

See also: iodination, thyroid hormone, thyroxine, diiodotyrosine.