Antagonis asam folat terutama dipakai sebagai antineoplastik.

Merriam-Webster Online Dictionary
aminopterin (noun)
a derivative CHNO of glutamic acid that is a folic acid antagonist and has been used as a rodenticide and antileukemic agent - 19 20 8 5
Aminopterin (Wikipedia)
Aminopterin ball-and-stick.png
IUPAC name
2-[ [4-{[(2,4-Diaminopteridin-6-yl)methyl]amino}benzoyl]amino]pentanedioic acid
Other names
4-Aminofolic acid
4-Aminopteroylglutamic acid
Aminopterin sodium
Aminopteroylglutamic acid
3D model (Jmol)
ECHA InfoCard 100.000.191
EC Number 200-209-9
Molar mass 440.41 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Aminopterin (or 4-aminopteroic acid), the 4-amino derivative of folic acid, is an antineoplastic drug with immunosuppressive properties often used in chemotherapy. Aminopterin is a synthetic derivative of pterin. Aminopterin works as an enzyme inhibitor by competing for the folate binding site of the enzyme dihydrofolate reductase. Its binding affinity for dihydrofolate reductase effectively blocks tetrahydrofolate synthesis. This results in the depletion of nucleotide precursors and inhibition of DNA, RNA, and protein synthesis.

It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.