The 4-carboxyaldehyde form of vitamin B 6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. [PubChem]
Pyridoxal is one of the natural forms available of vitamin B6, therefore, it is used for nutritional supplementation and for treating dietary shortage or imbalances.
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682