Thymidine
[CAS# 50-89-5]

Identification

• Classification: Organic raw materials >> Organic fluorine compound >> Fluoroanisole series
• Name: Thymidine
• Synonyms: 1-(2-Deoxy-beta-D-ribofuranosyl)-5-methyluracil; 1-(2-Deoxy-beta-D-ribofuranosyl)thymine; Thymine deoxyriboside; 2'-Deoxythymidine; 5-Methyldeoxyuridine
• Molecular Formula: C₁₀H₁₄N₂O₅
• Molecular Weight: 242.23
• Protein Sequence: T
• CAS Registry Number: 50-89-5
• EC Number: 200-070-4
• SMILES: CC1=CN(C(=O)NC1=O)[C@H]2C[C@@H]([C@H](O2)CO)O

Properties

• Density: 1.5±0.1 g/cm³, Calc.^*
• Melting point: 186-188 °C (Expl.)
• alpha: 18.6 ° (c=3, H2O)
• Index of Refraction: 1.584, Calc.^*
• Water solubility: SOLUBLE

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302+H312+H332-H315-H319-H335
• Safety Statements: P261-P280-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2A	H319
Germ cell mutagenicity	Muta.	1A	H340
Acute toxicity	Acute Tox.	4	H302

Discovery and Applications

Thymidine is a nucleoside that is crucial for the synthesis of DNA in cells. It consists of the nucleobase thymine, a pyrimidine base, bonded to a deoxyribose sugar. Thymidine is one of the four nucleosides that make up the DNA sequence, alongside adenosine, cytidine, and guanosine. Its primary role is in DNA replication and repair, and it is integral to the cell’s ability to divide and replicate genetic material.

Thymidine was first isolated and identified as a constituent of DNA in the early 20th century. Its structure was elucidated as part of the larger efforts to understand the components of nucleic acids. The discovery of thymidine came alongside the recognition that DNA, and not protein, is the molecule responsible for genetic inheritance. The identification of thymidine as a key component of DNA was essential for the development of molecular biology and genetics.

In terms of its biological function, thymidine is a building block of DNA. During DNA replication, the enzyme DNA polymerase incorporates thymidine into the growing DNA strand by pairing it with the adenine base on the complementary strand. This process is fundamental to the accurate duplication of genetic material during cell division. Thymidine is also involved in DNA repair processes, where it helps to restore damaged or mutated regions of the DNA sequence. Its incorporation into DNA is highly regulated, as the precise balance of nucleotides is critical for maintaining genome integrity.

Thymidine is synthesized within cells from deoxyuridine through the action of thymidylate synthase, which converts deoxyuridine monophosphate (dUMP) into thymidine monophosphate (dTMP). This enzymatic reaction requires the cofactor tetrahydrofolate. The availability of thymidine in cells is critical for proper DNA replication, particularly during cell division.

In addition to its biological function, thymidine has been used in a variety of applications in research and medicine. It is often utilized in laboratory experiments to study DNA replication and repair mechanisms. Thymidine can be labeled with radioactive isotopes, such as tritiated thymidine, to trace DNA synthesis and cell proliferation. This method has been instrumental in studying cell cycle dynamics, particularly in cancer research, where the rate of cell division is often abnormal.

Thymidine has also been used as a precursor in the synthesis of certain antiviral drugs. One such drug is zidovudine (AZT), which is a reverse transcriptase inhibitor used to treat HIV/AIDS. Zidovudine is a synthetic analogue of thymidine that inhibits the activity of the reverse transcriptase enzyme in HIV, preventing the virus from replicating its genetic material. AZT works by being incorporated into the viral RNA by reverse transcriptase, thereby halting further RNA synthesis. This therapeutic application of thymidine underscores its importance in both basic biology and medical treatment.

Thymidine analogs, such as 5-fluorouracil (5-FU), are also used in cancer chemotherapy. 5-FU is a drug that mimics thymidine and is incorporated into the DNA of rapidly dividing cancer cells, leading to disruption of their DNA synthesis and subsequent cell death. The selective targeting of cancer cells, which divide more rapidly than normal cells, is a key feature of the therapeutic use of thymidine analogs in cancer treatment.

Beyond its applications in medical treatments, thymidine plays an essential role in the biotechnology and pharmaceutical industries. It is used in the synthesis of nucleotides and nucleic acids for research and drug development. Additionally, it is employed in the development of assays to measure cell proliferation and DNA synthesis, which are valuable tools in both clinical diagnostics and experimental research.

In conclusion, thymidine is a critical nucleoside with fundamental biological functions in DNA replication, repair, and cellular division. Its discovery and characterization were pivotal in the development of molecular biology, and its applications in research, diagnostics, and therapy continue to be significant. As a key component of DNA, thymidine remains a central molecule in the study of genetics and the treatment of diseases such as cancer and HIV/AIDS.

References

2008. Effect of beta-casomorphin-7 on DNA synthesis in cell populations of newborn albino rats. Bulletin of Experimental Biology and Medicine, 145(2).
DOI: 10.1007/s10517-008-0052-3

2008. Chemical synthesis of oligodeoxyribonucleotides containing N3- and O4-carboxymethylthymidine and their formation in DNA. Nucleic Acids Research, 37(2).
DOI: 10.1093/nar/gkn946

2009. Functional in vitro model to examine cancer therapy cytotoxicity in maturing rat testis. Reproductive Toxicology, 27(1).
DOI: 10.1016/j.reprotox.2008.10.004