Aminopterin, an amino derivative of folic acid [
F0043], is a dihydrofolic acid reductase (DHFR) inhibitor. DHFR is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using nicotinamide adenine dinucleotide phosphate (NADPH) as electron donor, and a key enzyme in the synthesis of thymidylate and DNA. The inhibition causes the depletion of nucleotide precursors and inhibition of DNA. Aminopterin used to use as an antineoplastic agent in the treatment of leukemia. In the 1950’s, a less potent but less toxic methotrexate [
M1664] began to replace in clinical use. (The product is for research purpose only.)