'Novel alkyl side chain sulfone 1α,25-dihydroxyvitamin D3 analogs: A comparison of in vitro antiproliferative activities and in vivo calcemic activities'

The replacement of a t-butyl group with a trifluoromethyl group has profound effects on the biological profile of 1 alpha,25-dihydroxyvitamin D-3 sulfone analogs. Investigation of whether the improved biological activities are due to steric and electronic factors of the trifluoromethyl group led to the design, synthesis and biological evaluation of two analogous alkyl sulfone molecules, methyl sulfone (AU-16-ene-25-SO2-CH3) and isopropyl sulfone (AU-16-ene-25-SO2-i-Pr). These alkyl sulfones are sterically comparable to, but electronically very different from a trifluoromethyl group. The syntheses, antiproliferative activities and calcemic activities of these new alkyl sulfones are presented herein. In comparing the in vitro antiproliferative profiles of the new alkyl sulfone 1 alpha,25-dihydroxyvitamin D-3 analogs with the trifluoromethylsulfone and an analogous t-butyl sulfone, the activities increase in the following order: CH3