Formation of 19-nor-10-keto-25-hydroxyvitamin D3 in cultured mammalian cells.

Cultured dog kidney cells convert 25-hydroxyvitamin D3 into more polar metabolites during in vitro incubations. One elutes with 1,25-dihydroxyvitamin D3 from high pressure liquid chromatographic silica columns with hexane:isopropanol (9:1), but can be separated from 1,25-dihydroxyvitamin D3 by elution with dichloromethane:isopropanol (95:5). This peak has been isolated, purified and identified by mass spectral analysis to be 19-nor-10-keto-25-hydroxyvitamin D3.