Question

5-Fluorouracil, an anti-metabolite used in cancer treatment, is activated to:

• A. 5-fluoro-2-oxyuridylic acid
• B. 3-fluoro-3-deoxyuridylic acid
• C. 3-fluoro-3-oxyuridylic acid
• D. 5-fluoro-2-deoxyuridylic acid

Hint:

- 5-Fluorouracil is converted to 5-fluoro-2-deoxyuridylic acid (FdUMP), which inhibits thymidylate synthase and blocks DNA synthesis. 
- FdUMP is responsible for the drug’s action in chemotherapy, specifically targeting rapidly dividing cancer cells.

Answer 1

The Correct Option is D

5-Fluorouracil (5-FU) is a chemotherapy drug that works by inhibiting the synthesis of thymidylate, a critical nucleotide required for DNA replication. Upon administration, 5-fluorouracil is metabolized and activated in the body to form 5-fluoro-2-deoxyuridylic acid (FdUMP), which is the active form of the drug. FdUMP works by binding to the enzyme thymidylate synthase, thereby inhibiting the conversion of deoxyuridine monophosphate (dUMP) to thymidine monophosphate (dTMP), an essential building block for DNA synthesis. This inhibition causes DNA replication to stop, leading to cancer cell death. 

Why Other Options Are Incorrect: 
- (A) 5-fluoro-2-oxyuridylic acid: This compound does not represent the activated form of 5-fluorouracil. 
- (B) 3-fluoro-3-deoxyuridylic acid: This is not the correct metabolite of 5-fluorouracil. 
- (C) 3-fluoro-3-oxyuridylic acid: This is also not the correct product after activation of 5-fluorouracil. 

Thus, the correct activated form of 5-fluorouracil is 5-fluoro-2-deoxyuridylic acid (FdUMP).