4-Thiouracil

4-Thiouracil is a thionucleobase with cytostatic properties. 4-Thiouracil can be used as biological photoprobes to detect RNA structures and nucleic acid-nucleic acid contacts. 4-Thiouracil can also act as a strong ultraviolet A (UVA) photosensitizer, providing a source of the reactive oxygen species of O2. 4-Thiouracil is promising for research of photocross linking, photodamage, as well as photodynamic therapy.