title: Identification of 25,26-dihydroxyvitamin D3 as a rat renal 25-hydroxyvitamin D3 metabolite.
abstract: 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.
mesh_terms: D000818:Animals; D002112:Calcifediol; D002851:Chromatography, High Pressure Liquid; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D006887:Hydroxycholecalciferols / Q000032:analysis / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry; D008861:Microsomes / Q000032:analysis; D051381:Rats
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D002112:Calcifediol; C026032:25,26-dihydroxycholecalciferol