摘要：A new metabolic pathway of (24R)-24, 25-dihydroxyvitamin D3 [24, 25(OH)2D3] was clarified in the vivo experiments. After the administration of 24, 25(OH)2D3 to rats, a new monoglucuronide of a vitamin D metabolite was obtained from the bile together with 24, 25(OH)2D3 3- and 24-glucuronides. The genin of the metabolite was identified as 3-epi-24, 25(OH)2D3 in comparison with the synthetic sample based on the data from 1H-NMR, GC/MS, and LC/atmospheric pressure chemical ionization-MS. The conjugation position was determined to be the 24-hydroxy group by the LC/electrospray ionization-MS and -MS/MS/MS combined with derivatization. To our knowledge, this is the first reported instance of the epimerization of the 3-hydroxy group of vitamin D compound with no hydroxy group at the 1α-position.
关键词：3-epi-24, 25-dihydroxyvitamin D3;in vivo metabolite;synthesis;LC/MS;glucuronide
