25-26-dihydroxycholecalciferol and calcifediol-lactone

To elucidate the biosynthesis of 25-hydroxyvitamin D3-26,23-lactone, various vitamin D3 derivatives were incubated individually with kidney homogenates prepared from vitamin D3-supplemented chicks, a preparation known to produce the 25-hydroxyvitamin D3-26,23-lactone from 25-hydroxyvitamin D3. The 25-hydroxyvitamin D3-26, 23-lactone produced in vitro was then separated, purified, identified, and quantitated by consecutive analysis by high-pressure liquid chromatography. The naturally occurring 23(S), 25(R)-25-hydroxyvitamin D3-26,23-lactone was produced from 23(S),25-dihydroxyvitamin D3, 25(R),26-dihydroxyvitamin D3, and 23(S),25(R),26-trihydroxyvitamin D3. 23(S),25 (S)-25-Hydroxyvitamin D3-26,23-lactone was synthesized from 25(S),26-dihydroxyvitamin D3 and 23(S),25(S),26-trihydroxyvitamin D3. The relative amounts of 25-hydroxyvitamin D3-26,23-lactones generated from the following vitamin D3 derivatives used as substrate (23(S),25(S),26-trihydroxyvitamin D3; 23(R),25(R),26-trihydroxyvitamin D3; 23(S),25(R),26-trihydroxyvitamin D3; 23(R),25(S),26-trihydroxyvitamin D3; 23(S), 25-dihydroxyvitamin D3; 23(R),25-dihydroxyvitamin D3; 25(S),26-dihydroxyvitamin D3; and 25(R),26-dihydroxyvitamin D3) are, respectively, 15:1.7:24:3.3:2.5:0:1:1.7. These results indicate that when the lactonization at C-23 and C-26 positions of various vitamin D3 derivatives occurred the stereochemical configuration at their C-23 and/or C-25 positions was not changed and the difference of the stereochemical configurations determined the rate of lactonization.

Topics: Animals; Calcifediol; Calcitriol; Chickens; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Hydroxycholecalciferols; Kidney; Male; Molecular Conformation; Stereoisomerism

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Chickens; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Hydroxycholecalciferols; Hydroxylation; Kidney; Tritium; Vitamin D Deficiency

Here we report the use of newly developed and established techniques for the determination of plasma levels of a broad spectrum of vitamin D3 metabolites, including vitamin D3 and 25OHD3-lactone, in normal humans, chronic renal failure patients, and anephric subjects. The methodology described consisted of methanol-methylene chloride extraction, Lipidex-5000 chromatography with stepwise gradient elution, normal-phase HPLC with concave gradient elution, and sensitive ligand-binding assays. The results of the study strongly suggest an extrarenal source(s) for 24,25(OH)2D3 and 25,26(OH)2D3 and indicate that both 25OHD3-lactone and 1,25(OH)2D3 may be produced solely in the kidney of the human. Significant reductions or nondetectable plasma levels of vitamin D3 in the renal disease patients may reflect abnormalities in the hepatobiliary-intestinal and/or cutaneous metabolism of vitamin D.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Cholecalciferol; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Kidney Failure, Chronic; Methods; Nephrectomy

Topics: Animals; Biotransformation; Calcifediol; Cholecalciferol; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Ergocalciferols; Hydroxycholecalciferols; Male; Mass Spectrometry; Radioisotope Dilution Technique; Rats; Tritium

Topics: Animals; Calcifediol; Chickens; Chromatography, Gel; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Hydroxycholecalciferols; Kidney; Rickets; Tritium