4-Aminobutanal, also known as ó-aminobutyraldehyde, 4-aminobutyraldehyde, or GABA aldehyde, is a metabolite of putrescine and a biological precursor of ó-aminobutyric acid (GABA). It can be converted into GABA by the actions of diamine oxidase (DAO) and aminobutyraldehyde dehydrogenase (ABALDH) (e.g., ALDH9A1). Putrescine is converted into 4-aminobutanal via monoamine oxidase B (MAO-B). However, biosynthesis of GABA from polyamines like putrescine is a minor metabolic pathway in the brain.
The related compound ó-hydroxybutyraldehyde (GHBAL) is a prodrug of ó-hydroxybutyric acid (GHB) as well as a metabolic intermediate in the conversion of 1,4-butanediol (1,4-BD) into GHB. However, aliphatic aldehydes like GHBAL are caustic, strong-smelling, and foul-tasting, and ingestion is likely to be unpleasant and result in severe nausea and vomiting.