Natural 25,26-dihydroxyvitamin D3 is an epimeric mixture.
Natural 25,26-dihydroxyvitamin D3 is an epimeric mixture.
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天然 25,26-二羟基维生素 D3 是一种差向异构混合物。
DOI：
10.1073/pnas.80.17.5286
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发表时间：
1983
影响因子：
11.1
通讯作者：
DeLuca,HF
中科院分区：
文献类型：
--
作者：
Ikekawa,N;Koizumi,N;Ohshima,E;Ishizuka,S;Takeshita,T;Tanaka,Y;DeLuca,HF
使用鸡肾匀浆在体外制备放射性标记的 25,26-二羟基维生素 D3，并在大鼠体内使用 [23,24-3H]-25-羟基维生素 D3 制备放射性标记的 25,26-二羟基维生素 D3。这些化合物与合成的 (25S)-和 (25R)-25,26-二羟基维生素 D3 混合，转化为相应的 (+)-α-甲氧基-α-三氟甲基苯基乙酰酯，并进行高效液相色谱分离衍生的差向异构体。放射性标记的 25,26-二羟基维生素 D3 衍生物是 25S 和 25R 异构体的 1:1 混合物。同样，从给予大量维生素 D3 的大鼠血浆中分离出的未标记的 25,26-二羟基维生素 D3 被证明是 S 和 R 异构体的 1:1 混合物。因此，天然存在的25,26-二羟基维生素D3是25R和25S异构体的混合物，而不仅仅是之前报道的S异构体。
Radiolabeled 25,26-dihydroxyvitamin D3 was prepared in vitro by using chicken kidney homogenates and in vivo in rats from [23,24-3H]-25-hydroxyvitamin D3. These compounds were mixed with synthetic (25S)- and (25R)-25,26-dihydroxyvitamin D3, converted to the corresponding (+)-alpha-methoxy-alpha-trifluoromethylphenylacetyl esters, and subjected to high-performance liquid chromatography that separates the derivatized epimers. The radiolabeled 25,26-dihydroxyvitamin D3 derivatives were a 1:1 mixture of the 25S and 25R isomers. Similarly unlabeled 25,26-dihydroxyvitamin D3 isolated from the plasma of rats given large amounts of vitamin D3 was shown to be a 1:1 mixture of the S and R isomers. Therefore, naturally occurring 25,26-dihydroxyvitamin D3 is a mixture of the 25R and 25S isomers and not just the S isomer reported previously.