Flarakos Caroline Ceailles, Weiskopf Andrew, Robinson Matthew, Wang Guoshun, Vouros Paul, Sasso Gino J, Uskokovic Milan R, Reddy G Satyanarayana
The Barnett Institute and Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, United States.
Epimer, LLC, 1 Valley View Drive, North Smithfield, RI 02896, United States.
Steroids. 2017 Mar;119:18-30. doi: 10.1016/j.steroids.2016.12.013. Epub 2017 Jan 12.
Analogs of 1α,25-dihydroxyvitamin D (S1) with 20-epi modification (20-epi analogs) possess unique biological properties. We previously reported that 1α,25-dihydroxy-20-epi-vitamin D (S2), the basic 20-epi analog is metabolized into less polar metabolites (LPMs) in rat osteosarcoma cells (UMR-106) but not in a perfused rat kidney. Furthermore, we also noted that only selective 20-epi analogs are metabolized into LPMs. For example, 1α,25-dihydroxy-16-ene-20-epi-vitamin D (S4), but not 1α,25-dihydroxy-16-ene-23-yne-20-epi-vitamin D (S5) is metabolized into LPMs. In spite of these novel findings, the unequivocal identification of LPMs has not been achieved to date. We report here on a thorough investigation of the metabolism of S4 in UMR-106 cells and isolated two major LPMs produced directly from the substrate S4 itself and two minor LPMs produced from 3-epi-S4, a metabolite of S4 produced through C-3 epimerization pathway. Using GC/MS, ESI-MS and H NMR analysis, we identified all the four LPMs of S4 as 25-hydroxy-16-ene-20-epi-vitamin D-1-stearate and 25-hydroxy-16-ene-20-epi-vitamin D-1-oleate and their respective C-3 epimers. We report here for the first time the elucidation of a novel pathway of metabolism in UMR-106 cells in which both 1α,25(OH)-16-ene-20-epi-D and 1α,25(OH)-16-ene-20-epi-3-epi-D undergo C-1 esterification into stearic and oleic acid esters.
具有20-表位修饰的1α,25-二羟基维生素D类似物（S1）（20-表位类似物）具有独特的生物学特性。我们之前报道过，基本的20-表位类似物1α,25-二羟基-20-表位维生素D（S2）在大鼠骨肉瘤细胞（UMR-106）中代谢为极性较小的代谢产物（LPMs），但在灌注的大鼠肾脏中则不会。此外，我们还注意到只有选择性的20-表位类似物会代谢为LPMs。例如，1α,25-二羟基-16-烯-20-表位维生素D（S4）会代谢为LPMs，而1α,25-二羟基-16-烯-23-炔-20-表位维生素D（S5）则不会。尽管有这些新发现，但迄今为止尚未明确鉴定出LPMs。我们在此报告了对UMR-106细胞中S4代谢的深入研究，分离出了直接由底物S4本身产生的两种主要LPMs以及由3-表位-S4（通过C-3差向异构化途径产生的S4代谢产物）产生的两种次要LPMs。通过气相色谱/质谱（GC/MS）、电喷雾电离质谱（ESI-MS）和核磁共振氢谱（H NMR）分析，我们将S4的所有四种LPMs鉴定为25-羟基-16-烯-20-表位维生素D-1-硬脂酸酯和-25-羟基-16-烯-20-表位维生素D-1-油酸酯及其各自的C-3差向异构体。我们在此首次报告了UMR-106细胞中一种新的代谢途径的阐明，其中1α,25(OH)-16-烯-20-表位-D和1α,25(OH)-16-烯-20-表位-3-表位-D都会发生C-1酯化生成硬脂酸酯和油酸酯。
