Synthesis and biological evaluation of 4-substituted vitamin d and 14-epi-previtamin d analogs.

We synthesized the 4-hydroxy and 4-methoxy analogs of active vitamin D(3) (1alpha,25(OH)(2)D(3), 1) and its C14-epimer with the previtamin D(3) form of 14-epi-1alpha,25(OH)(2)preD(3) (14-epi-pre1). Their vitamin D receptor (VDR) binding affinity and osteocalcin promoter transactivation activity in HOS cells were evaluated, and had lower activity than the natural hormone (1) and 14-epi-pre1, respectively.