Pantoic acid is the alpha hydroxy acid with the formula HOCH2C(CH3)2CH(OH)CO2H. The compound is almost always encountered in a biological context, as an aqueous solution of its conjugate base pantoate HOCH2C(CH3)2CH(OH)CO2-. The amide of pantoic acid with β-alanine is pantothenic acid (vitamin B5),[1] a component of coenzyme A.
Its biosynthesis proceeds from ketoisovalerate by hydroxymethylation:
(CH3)2CHC(O)CO2− + CH2O → HOCH2(CH3)2CC(O)CO2−
This conversion is catalyzed by ketopantoate hydroxymethyltransferase, which gives ketopantoate. Ketopantoate is reduced by ketopantoate reductase to pantoate, using NADH as the hydride source.[2]
The amide derived from pantoic acid and GABA is the pharmaceutical drug hopantenic acid.