Stercobilin is an end-stage metabolite of
hemoglobin, a component of red blood cells. It has been found that there is a significantly lower concentration of
stercobilin in the urine of people diagnosed with
autism spectrum disorders, suggesting potential use as a
biomarker. In vitro, we have synthesized
stercobilin from its precursor
bilirubin through a reduction reaction proceeded by an oxidation reaction. In addition, we have isotopically labeled the
stercobilin product with
deuterium using this protocol. Nuclear magnetic resonance investigations show the products of the unlabeled
stercobilin (Rxn 1) and the deuterated
stercobilin (Rxn 2) both had a loss of signals in the 5.0- to 7.0-ppm range indicating proper conversion to
stercobilin. Changes in the multiplicity of the sp3 region of the
proton nuclear magnetic resonance suggest proper
deuterium incorporation. Mass spectrometry studies of Rxn 1 show a difference in fragmentation patterns than that of Rxn 2 proposing potential locations for
deuterium incorporation. This isotopologue of
stercobilin is stable (>6 mo), and further analysis permits investigation for its use as a
biomarker and potential quantitative diagnostic probe for
autism spectrum disorders.