These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: (23S)-1,23,25-Trihydroxyvitamin D3: its biologic activity and role in 1 alpha,25-dihydroxyvitamin D3 26,23-lactone biosynthesis.
    Author: Horst RL, Wovkulich PM, Baggiolini EG, Uskoković MR, Engstrom GW, Napoli JL.
    Journal: Biochemistry; 1984 Aug 14; 23(17):3973-9. PubMed ID: 6548386.
    Abstract:
    (23S)-1,23,25-Trihydroxyvitamin D3 was isolated from bovine kidney homogenates incubated with 1,25-dihydroxyvitamin D3 by sequential chromatography through one Sephadex LH-20 column and three high-performance liquid chromatography systems. Ultraviolet absorption spectroscopy and mass spectrometry confirmed the structural assignment. One high-performance liquid chromatography system separated the R and S epimers of 1,23,25-trihydroxyvitamin D3 and indicated that the natural product had the S configuration. Plasma pharmacokinetic studies in rats showed that (23S)-1,23,25-trihydroxy[3H]vitamin D3 was rapidly cleared from plasma (t1/2 = 60 min). 1 alpha,25-Dihydroxy[3H]vitamin D3 26,23-lactone appeared concurrently with the disappearance of (23S)-1,23,25-trihydroxy[3H]vitamin D3. Experiments with radioinert compounds showed that 1,25-dihydroxyvitamin D3 and (23S)-1,23,25-trihydroxyvitamin D3 were efficient precursors to 1,25-dihydroxyvitamin D3 26,23-lactone both in intact and in nephrectomized rats. (25S)-1,25,26-Trihydroxyvitamin D3, however, was ineffective at raising plasma 1,25-dihydroxyvitamin D3 26,23-lactone concentrations. These results confirm the presence of extrarenal 1,25-dihydroxyvitamin D3 23(S)-hydroxylase(s) and demonstrate that C-23 hydroxylation of 1,25-dihydroxyvitamin D3 precedes C-26 hydroxylation in the formation of 1,25-dihydroxyvitamin D3 26,23-lactone. (23S)-1,23,25-Trihydroxyvitamin D3 had no intestinal calcium absorptive or bone calcium resorptive activity when dosed to vitamin D deficient rats at levels up to 500 ng. C-23 oxidation, therefore, appears to be a physiologic pathway of 1,25-(OH)2D3 metabolism and a major pathway for the deactivation of pharmacologic levels of 1,25-dihydroxyvitamin D3.
    [Abstract] [Full Text] [Related] [New Search]