Identification of 25,26-Dihydroxyvitamin D3 as a Rat Renal 25-Hydroxyvitamin D3 Metabolite

Joseph L. Napoli, Richard T. Okita, Bettie Sue Masters, Ronald L. Horst

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


25,26-Dihydroxyvitamin D3 [25,26-(OH)2D3] was unequivocally identified as a major renal microsomal metabolite of 25-hydroxyvitamin D3 in rats fed a vitamin D sufficient diet. The structural assignment was based on a comparison of the high-performance liquid chromatograms of synthetic and in vitro generated 25,26-(OH)2D3 through four different systems, the ultraviolet absorbance and mass spectral characteristics of biological 25,26-(OH)2D3, and the chromatographic and mass spectral characteristics of the sodium metaperiodate cleavage product of the metabolite. The enzymic synthesis of 25,26-(OH)2D3 was inhibited 60-80% by a semipurified goat anti-rat NADPH-cytochrome P-450 reductase. This implicates cytochrome P-450 as the probable terminal oxidase of the 25-hydroxyvitamin D3-26-hydroxylase system. The methodology used to assay rat renal 25-OH-D3- hydroxylases is also discussed.

Original languageEnglish (US)
Pages (from-to)5865-5871
Number of pages7
Issue number20
StatePublished - Sep 1981

ASJC Scopus subject areas

  • Biochemistry


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