Yamada S, Ino E, Takayama H, Horiuchi N, Shinki T, Suda T, Jones G, DeLuca H F
Proc Natl Acad Sci U S A. 1985 Nov;82(22):7485-9. doi: 10.1073/pnas.82.22.7485.
In vitro metabolism of 25-hydroxy-24-oxovitamin D3 was studied in kidney homogenates from vitamin D-supplemented chickens and rats. In chicken homogenates, 25-hydroxy-24-oxovitamin D3 was converted predominantly to 23,25-dihydroxy-24-oxovitamin D3, 24,25-dihydroxyvitamin D3, and 23,24,25-trihydroxyvitamin D3. In rat homogenates, 25-hydroxy-24-oxovitamin D3 was not converted to either 24,25-dihydroxyvitamin D3 or 23,24,25-trihydroxyvitamin D3, but it was converted to 23,25-dihydroxy-24-oxovitamin D3 and 23-hydroxy-24,25,26,27-tetranorvitamin D3. The latter metabolite was not produced by the chicken preparations. The stereochemical configuration at C-24 of the 24,25-dihydroxyvitamin D3 produced by chicken homogenates was determined to be S. This contrasts with the R configuration of 24,25-dihydroxyvitamin D3 produced by 24-hydroxylation of 25-hydroxyvitamin D3. These results suggest that chickens have an enzyme that can reduce the 24-oxo group to 24S-hydroxyl group, whereas rats do not.
在补充了维生素D的鸡和大鼠的肾脏匀浆中研究了25-羟基-24-氧代维生素D3的体外代谢。在鸡的匀浆中,25-羟基-24-氧代维生素D3主要转化为23,25-二羟基-24-氧代维生素D3、24,25-二羟基维生素D3和23,24,25-三羟基维生素D3。在大鼠的匀浆中,25-羟基-24-氧代维生素D3既不转化为24,25-二羟基维生素D3也不转化为23,24,25-三羟基维生素D3,但它会转化为23,25-二羟基-24-氧代维生素D3和23-羟基-24,25,26,27-四去甲维生素D3。后一种代谢产物在鸡的制剂中未产生。鸡匀浆产生的24,25-二羟基维生素D3在C-24位的立体化学构型被确定为S型。这与由25-羟基维生素D3的24-羟化产生的24,25-二羟基维生素D3的R构型形成对比。这些结果表明鸡有一种能将24-氧代基团还原为24S-羟基的酶,而大鼠则没有。