Which of the following is a dihydrofolate reductase inhibitor: March 2009

Ans. B: Methotrexate Dihydrofolate reductase inhibitor is a molecule that inhibits the function of dihydrofolate reductase, and is a type of antifolate. Since folate is needed by rapidly dividing cells to make thymine, this effect may be used to therapeutic advantage. For example, methotrexate is used as cancer chemotherapy because it can prevent neoplastic cells from dividing. Bacteria also need DHFR to grow and multiply and hence inhibitors selective for bacterial vs. host DHFR have found application as antibacterial agents Variety of drug act as inhibitors of dihydrofolate reductase: The antibiotic trimethoprim and its derivatives brodimoprim, tetroxoprim, and iclaprim. The antimalarial drug pyrimethamine. The chemotherapeutic agents methotrexate and pemetrexed. Methotrexate acts on this enzyme binding to it some 1000 times more tightly than folate itself.