Dihydrofolate reductase inhibitor

Cellular enzyme inhibitor

A dihydrofolate reductase inhibitor (DHFR 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.[1][2] Bacteria also need DHFR to grow and multiply and hence inhibitors selective for bacterial vs. host DHFR have found application as antibacterial agents.[3] An extensive review of the chemical space of small-molecules that inhibit DHFR is summarized in

Tetrahydrofolate synthesis pathway

Classes of small-molecules employed as inhibitors of dihydrofolate reductase include diaminoquinazoline and diaminopyrroloquinazoline, Most of the above specified inhibitors are structural analogues of the substrate dihydrofolate and bind to the active site of the enzyme. Further, it has been recently shown that, in E. coli DHFR, allosteric site binders can inhibit the enzyme either uncompetitively or non-competitively. The examples provided below are specific molecules belonging to one of the above-mentioned classes.

  • the experimental antimalarial and anti-toxoplasmosis compound JPC-2056[4]
  • Oral piritrexim, a treatment for metastatic urothelial cancer.[5]
  • Cycloguanil, a metabolite of proguanil (a component of the oral antimalarial atovaquone-proguanil, or Malarone), although this has been called into question (see its article)

References

  1. ^ Huennekens FM (1994). "The methotrexate story: a paradigm for development of cancer chemotherapeutic agents". Advances in Enzyme Regulation. 34: 397–419. doi:10.1016/0065-2571(94)90025-6. PMID 7942284.
  2. ^ McGuire JJ (2003). "Anticancer antifolates: current status and future directions". Current Pharmaceutical Design. 9 (31): 2593–613. doi:10.2174/1381612033453712. PMID 14529544.
  3. ^ Hawser S, Lociuro S, Islam K (March 2006). "Dihydrofolate reductase inhibitors as antibacterial agents". Biochemical Pharmacology. 71 (7): 941–8. doi:10.1016/j.bcp.2005.10.052. PMID 16359642.
  4. ^ Mui EJ, Schiehser GA, Milhous WK, Hsu H, Roberts CW, Kirisits M, Muench S, Rice D, Dubey JP, Fowble JW, Rathod PK, Queener SF, Liu SR, Jacobus DP, McLeod R (March 2008). "Novel triazine JPC-2067-B inhibits Toxoplasma gondii in vitro and in vivo". PLOS Neglected Tropical Diseases. 2 (3): e190. doi:10.1371/journal.pntd.0000190. PMC 2254147. PMID 18320016.
  5. ^ de Wit R, Kaye SB, Roberts JT, Stoter G, Scott J, Verweij J (February 1993). "Oral piritrexim, an effective treatment for metastatic urothelial cancer". British Journal of Cancer. 67 (2): 388–90. doi:10.1038/bjc.1993.71. PMC 1968166. PMID 8431372.
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Pharmacology: enzyme inhibition
Class
  • Competitive inhibition
  • Uncompetitive inhibition
  • Non-competitive inhibition
  • Suicide inhibition
  • Mixed inhibition
Substrate
Oxidoreductase (EC 1)
  • 1.1 Aldose reductase
  • HMG-CoA reductase
  • 1.5 Dihydrofolate reductase
Transferase (EC 2)
Hydrolase (EC 3)
Lyase (EC 4)
Miscellaneous
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SPs/MIs
(M phase)
Block microtubule assembly
Block microtubule disassembly
DNA replication
inhibitor
DNA precursors/
antimetabolites
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Folic acid
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Pyrimidine
Deoxyribonucleotide
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Antifolates
(inhibit bacterial
purine metabolism,
thereby inhibiting
DNA and RNA
synthesis)
DHFR inhibitor
Sulfonamides
(DHPS inhibitor)
Short-acting
Intermediate-acting
Long-acting
Other/ungrouped
Combinations
Other DHPS inhibitors
Quinolones
(inhibit bacterial
topoisomerase
and/or DNA gyrase,
thereby inhibiting
DNA replication)
1st generation
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2nd generation
3rd generation
4th generation
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Related (DG)
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Alveo-
late
Apicom-
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Conoidasida/
(Coccidiostats)
Cryptosporidiosis
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4-Methanolquinolines
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DHFR inhibitors
Sulfonamides
Co-formulation
Sesquiterpene
lactones
Other
Combi-
nations
Fixed-dose (co-formulated) ACTs
Other combinations
(not co-formulated)
  • artesunate/mefloquine
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  • quinine/clindamycin
  • quinine/doxycycline
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Babesiosis
Cilio-
phora
Stramen-
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