Indoxyl

Indoxyl is an organic compound that serves as a key intermediate in the production of indigo, the deep blue dye. In plants that produce indigo dyes, indican is hydrolyzed to yield indoxyl and glucose. Indoxyl is typically colorless and relatively reactive; in air it readily oxidizes and couples with another indoxyl molecule to form indigo, the insoluble blue pigment. In dyeing practices, indigo can be formed from indoxyl via oxidation, though industrial processes often rely on related leuco forms that are reduced to soluble intermediates during vat dyeing.

Industrial and laboratory contexts sometimes generate indoxyl by hydrolysis of indican or by synthetic routes that provide a precursor to indigo. The indoxyl–indigo relationship is central to traditional natural indigo production and is also referenced in discussions of dye chemistry and pigment formation.

In biology and medicine, indoxyl appears in the context of tryptophan metabolism. Certain gut bacteria convert tryptophan to indole, which is absorbed and transported to the liver where it can be metabolized to indoxyl and then to indoxyl sulfate. Indoxyl sulfate is a well-recognized circulating metabolite and is studied as a uremic toxin, with elevated levels associated with kidney dysfunction.

Safety: Indoxyl and its derivatives are reactive and, depending on context, can be irritants or reactive intermediates. Proper handling and storage under appropriate conditions are advised in laboratory settings.

See also: Indigo dye, Indican, Indoxyl sulfate, Leucoindigo.