2-Thiouracil is a chemical derivative of

uracil Uracil () (nucleoside#List of nucleosides and corresponding nucleobases, symbol U or Ura) is one of the four nucleotide bases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via ...

in which the oxygen atom in the 2-position of the ring is

substituted Substitution may refer to: Arts and media *Substitution (poetry), a variation in poetic scansion *Substitution (theatre), an acting methodology Music *Chord substitution, swapping one chord for a related one within a chord progression *Tritone ...

by sulfur.

Medical use

The substance is a historically relevant anti-thyroid preparation.

Edwin Astwood Edwin Andre Astwood (born 24 August 1973) is a politician from the Turks and Caicos Islands who has been Leader of the Opposition since 2021 Turks and Caicos Islands general election, February 2021 and Leader of the PDM party since June 2021. He ...

used it in 1943 as therapy for

Graves' disease Graves' disease, also known as toxic diffuse goiter or Basedow's disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyro ...

for the first time. Thiouracil inhibits thyroid activity by blocking the enzyme

thyroid peroxidase Thyroid peroxidase, also called thyroperoxidase (TPO), thyroid specific peroxidase or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms ...

. Its use in recent times has been replaced by advent of more potent and safer antithyroid drugs. It occurs in seeds of Brassica and Crucifera species. Thiouracil has been used as antithyroid, coronary vasodilator, and in congestive heart failure although its use has been largely supplanted by other drugs.

References

Pyrimidines IARC Group 2B carcinogens Thioureas Nucleobases {{heterocyclic-stub