Rat CYP24 catalyses 23S-hydroxylation of 26,26,26,27,27,27-hexafluorocalcitriol in vitro

Xenobiotica. 1998 May;28(5):457-63. doi: 10.1080/004982598239380.


1. Kidney mitochondrial 24-hydroxylase cytochrome P450 (CYP24) catalyses sequential hydroxylation at both C-24 and C-23 positions of calcidiol and calcitriol. Here, we have investigated the in vitro metabolism of a hexafluorinated derivative of calcitriol, 26,26,26,27,27,27-hexafluorocalcitriol (ST-630), in a reconstituted system by using recombinant Escherichia coli membrane fractions containing rat CYP24. 2. When ST-630 was incubated with CYP24 supplemented with bovine adrenodoxin and NADPH-adrenodoxin reductase, a distinct metabolite could be observed. This metabolite was found to be 26,26,26,27,27,27-hexafluoro-23S-hydroxcalcitriol, a biologically active metabolite of ST-630, based on cochromatography on HPLC and mass spectrometric analysis. 3. These results show the direct evidence that CYP24 plays an essential role in the metabolism of ST-630 to yield its 23S-hydroxylated metabolite, as observed in cultured cells and experimental animal studies.

MeSH terms

  • Adrenodoxin / metabolism
  • Animals
  • Biotransformation
  • Calcitriol / analogs & derivatives*
  • Calcitriol / metabolism
  • Calcitriol / pharmacokinetics
  • Cattle
  • Cloning, Molecular
  • Cytochrome P-450 Enzyme System / metabolism*
  • Escherichia coli
  • Ferredoxin-NADP Reductase / metabolism
  • Hydroxylation
  • Kidney / enzymology*
  • Kinetics
  • Mitochondria / enzymology*
  • Rats
  • Recombinant Proteins / metabolism
  • Steroid Hydroxylases / metabolism*
  • Substrate Specificity
  • Vitamin D3 24-Hydroxylase


  • Recombinant Proteins
  • Adrenodoxin
  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases
  • Vitamin D3 24-Hydroxylase
  • Ferredoxin-NADP Reductase
  • Calcitriol
  • 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3