Isolation and identification of 2α,25-dihydroxyvitamin D3, a new metabolite from Pseudonocardia autotrophica 100U-19 cells incubated with Vitamin D3

Pseudonocardia autotrophica converted Vitamin D3 to 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3. The hydroxylation of Vitamin D3 with P. autotrophica was enhanced by the addition of cyclodextrin. In this microbial hydroxylation, a new Vitamin D3 metabolite was observed in the reaction mixture of P. autotrophica and Vitamin D3, and was isolated in a pure form by several steps of chromatography. The structure of the new metabolite was determined to be 2α,25-dihydroxyvitamin D3 by UV, NMR and mass spectroscopic analyses. Biological evaluation of the new metabolite was conducted by means of several experiments.