Subject - Biochemistry

Uracil is the common trivial name for 1H-pyrimidin-2,4-dione.

The molecular formula is ${\text{C}}_4{\text{H}}_4{\text{N}}_2{\text{O}}_2$ and the molecular mass (${\mathit{M}}_{\mathit{r}}$) is 112.09. Uracil forms colorless needles with a melting point of 338 $\text{°C}$.

Fig.1

Structural formula of uracil

In addition to the thermodynamically stable dione structure, uracil can exist in three tautomeric forms, two enols and an aromatic diol (pyrimidine-2,4-diol).

The pyrimidine base is closely related to thymine (5-methyluracil). Uracil or its nucleoside uridine are constituents of ribonucleic acid (RNA) from which it can be obtained by hydrolysis. In RNA, uracil is bound to adenine via two hydrogen bonds.

Derivatives of uracil are used in medicine as drugs, e.g. as diuretics and as anti-thyroid medications to inhibit the synthesis of thyroid hormones (thyreostatics, 2-thiouracil). Fluorouracil is an anti-metabolite of thymine and is used as a cytostatic drug. Other applications for uracil derivatives are its use as inhibitor of photosynthesis and as herbicide.