(6R,S)-5,6,7,8-Tetrahydrofolic acid (THFA), the reduced form of folic acid, serves as a cofactor in methyltransferase reactions and is the major one-carbon carrier in one carbon metabolism. Its metabolites participate in the synthesis of thymidine for incorporation into DNA or the synthesis of purines, as well as in the formation of methionine, which can be converted to the ubiquitous methyl donor, S-adenosylmethionine . THFA has also been used to study the activation of metabolite-binding riboswitches.

Tetrahydrofolic acid (5,6,7,8-tetrahydrofolic acid) is a vitamin B9 derivative that is a common one-carbon donor in organisms and is involved in growth and metabolism.

10-Formyltetrahydrofolic acid disodium, a derivative of tetrahydrofolic acid, serves as a formyl group donor in anabolic processes. It functions as a substrate for formyltransferase reactions, playing a crucial role in purine biosynthesis [1].

N-(4-Aminobenzoyl)-L-glutamic acid is an oxidation product and a metabolite of tetrahydrofolate.1Levels of N-(4-aminobenzoyl)-L-glutamic acid are increased in the plasma of mice fed a high folic acid-containing diet.2 1.Reed, L.S., and Archer, M.C.Oxidation of tetrahydrofolic acid by airJ. Agric. Food Chem.28(4)801-805(1980) 2.Burton, M.A., Antoun, E., Penailillo, R.S., et al.Folic acid induces intake-related changes in the mammary tissue transcriptome of C57BL/6 miceNutrients12(9)2821(2020)

Dihydrofolic acid (7,8-Dihydrofolic acid) is a folic acid derivative that produces tetrahydrofolic acid in the presence of dihydrofolic acid reductase.

Aminopterin (4-Aminofolic acid) is a synthetic folic acid derivative whose metabolite is a competitive inhibitor of dihydrofolate reductase

Aditoprime (Aditoprim) is a selective inhibitor of bacterial dihydrofolate reductase (DHFR) that inhibits the transformation of dihydrofolic acid to tetrahydrofolic acid. Aditoprime shows good antibacterial activity and broad antimicrobial spectrum, and moreover, excellent pharmacokinetics. Aditoprime inhibits L.casei and E.coli DHFR with IC 50 of 520 and 47 nM, respectively [1] [2] [3].