Potent, Selective and Low-Calcemic Inhibitors of CYP24 Hydroxylase:  24-Sulfoximine Analogues of the Hormone 1α,25-Dihydroxyvitamin D₃

A dozen 24-sulfoximine analogues of the hormone 1alpha,25-dihydroxyvitamin D(3) were prepared, differing not only at the stereogenic sulfoximine stereocenter but also at the A-ring. Although these sulfoximines were not active transcriptionally and were only very weakly antiproliferative, some of them are powerful hydroxylase enzyme inhibitors. Specifically, 24-(S)-NH phenyl sulfoximine 3a is an extremely potent CYP24 inhibitor (IC(50) = 7.4 nM) having low calcemic activity. In addition, this compound shows high selectivity toward the CYP24 enzyme in comparison to CYP27A1 (IC(50) > 1000 nM) and CYP27B (IC(50) = 554 nM).