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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1983 Sep;80(17):5286–5288. doi: 10.1073/pnas.80.17.5286

Natural 25,26-dihydroxyvitamin D3 is an epimeric mixture.

N Ikekawa, N Koizumi, E Ohshima, S Ishizuka, T Takeshita, Y Tanaka, H F DeLuca
PMCID: PMC384238  PMID: 6577424

Abstract

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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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