A pyridinecarbaldehyde that is pyridine-4-carbaldehyde bearing methyl, hydroxy and hydroxymethyl substituents at positions 2, 3 and 5 respectively. The 4-carboxyaldehyde form of vitamin B6, it is converted into pyridoxal phosphate, a coenzyme for the synthesis of amino acids, neurotransmitters, sphingolipids and aminolevulinic acid. ChEBI: Pyridoxal is a pyridinecarbaldehyde that is pyridine-4-carbaldehyde bearing methyl, hydroxy and hydroxymethyl substituents at positions 2, 3 and 5 respectively. The 4-carboxyaldehyde form of vitamin B6, it is converted into pyridoxal phosphate, a coenzyme for the synthesis of amino acids, neurotransmitters, sphingolipids and aminolevulinic acid. It has a role as a cofactor, a human metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a mouse metabolite. It is a vitamin B6, a pyridinecarbaldehyde, a member of methylpyridines, a monohydroxypyridine and a hydroxymethylpyridine. It is a conjugate base of a pyridoxal(1+).