Metabolism of selective 20-epi-vitamin D analogs in rat osteosarcoma UMR-106 cells: Isolation and identification of four novel C-1 fatty acid esters of 1α,25-dihydroxy-16-ene-20-epi-vitamin D.

Analogs of 1α,25-dihydroxyvitamin D (S1) with 20-epi modification (20-epi analogs) possess unique biological properties. We previously reported that 1α,25-dihydroxy-20-epi-vitamin D (S2), the basic 20-epi analog is metabolized into less polar metabolites (LPMs) in rat osteosarcoma cells (UMR-106) but not in a perfused rat kidney. Furthermore, we also noted that only selective 20-epi analogs are metabolized into LPMs.