D-erythrose 4-sodium phosphate is the sodium phosphate of the monosaccharide erythrose. Erythritol is actually converted to D-erythrose 4-phosphate involving three isomerases.
4-methyl-2-Oxovalerate is an immediate precursor and metabolite of L-leucine. It is a precursor leading to the synthesis of 2-methylpropyl glucosinolate, via L-leucine, in plants. 4-methyl-2-Oxovalerate is one of several plasma metabolites found to differ significantly between type 2 diabetes and control subjects.
(+)-Biotin 4-amidobenzoic acid is a substrate of biotinidase, which cleaves biotin amide to give biotin in vivo. Biotin is an essential coenzyme for certain carboxylases and is used to modify histones and regulate gene transcription. Biotinidase has key roles in intestinal absorption of biotin, the transport of biotin in plasma, and in the regulation of histone biotinylation. (+)-Biotin 4-amidobenzoic acid is hydrolyzed by biotinidase to release 4-aminobenzoic acid (PABA), which can be quantified by either fluorescent or colorimetric methods. This approach is used in biotinidase activity assays in newborn screening protocols to evaluate biotinidase deficiency.
(±)-Equol 4’-sulfate is a gut-mediated phase II metabolite of the isoflavonoid phytoestrogen (±)-equol .[1] It has been used as a standard for the quantification of unconjugated equol in rat plasma.[2]