| Two novel metabolic pathways of 22-oxacalcitriol (OCT). C-25 dehydration and C-3 epimerization and biological activities of novel OCT metabolites. | |
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MedLine Citation:
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PMID: 12417596 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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22-Oxacalcitriol (OCT) is an analog of calcitriol, characterized by potent differentiation-inducing activity and low calcemic liability. The metabolism of OCT has been studied and its polar metabolites, such as 24/26-hydroxylated-OCT and hexanor-1 alpha,20-dihydroxyvitamin D(3) (1 alpha,20(OH)(2)D(3)), have been identified. In contrast, little is known about the less polar metabolites of OCT, which have been found in relatively large amounts. In this study, the in vitro metabolism of OCT was studied in UMR 106, Caco-2, and LLC-PK(1) cells to identify the less polar metabolites and to assess their biological activity. OCT was initially metabolized to three less polar metabolites, 3-epi-OCT and two dehydrates, 25-dehydroxy- 25-ene-22-oxa-1 alpha(OH)D(3) (25-ene-22-oxa-1 alpha(OH)D(3)) and 25-dehydroxy-24-ene-22-oxa-1 alpha(OH)D(3) (24-ene-22-oxa-1 alpha(OH)D(3)). We also observed further metabolites, the two C-3 epimers of the C-25 dehydrates, 25-ene-3-epi-22-oxa-1 alpha(OH)D(3) and 24-ene-3-epi-22-oxa-1 alpha(OH)D(3). The structures of these metabolites were successfully assigned by (1)H NMR and LC-MS analyses. The three cell lines differ in their ability to metabolize OCT through the C-3 epimerization or the C-25 dehydration pathway. The biological activity of the OCT metabolites assessed by a luciferase reporter gene transcriptional activation system, binding assays for the vitamin D receptor (VDR) and vitamin D-binding protein (DBP), and assays for regulatory activities of cell differentiation and proliferation was found to be lower than that of OCT. Thus, both the C-3 epimerization and C-25 dehydration may work to reduce the biological activity of OCT. |
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Authors:
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Maya Kamao; Syuichiro Tatematsu; Susumi Hatakeyama; Keiichi Ozono; Noboru Kubodera; G Satyanarayana Reddy; Toshio Okano |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2002-11-01 |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 278 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 2003 Jan |
Date Detail:
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Created Date: 2003-01-13 Completed Date: 2003-02-14 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: United States |
Other Details:
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Languages: eng Pagination: 1463-71 Citation Subset: IM |
Affiliation:
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Department of Hygienic Sciences, Kobe Pharmaceutical University, Kobe 658-8558, Japan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Calcitriol / analogs & derivatives*, chemistry, metabolism*, pharmacology Cell Differentiation / drug effects Cell Division / drug effects Cell Line Chromatography, High Pressure Liquid Humans |
| Chemical | |
Reg. No./Substance:
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103909-75-7/maxacalcitol; 32222-06-3/Calcitriol |
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