Calcipotriol (7) VitD 3 (6) Viability EC 50 (nM) >10000 >10000 >10000 >10000 >10000 >10000 >10000 >10000 >10000 >10000 >10000 >10000 R para-substituted i Pr analogs 55a and 55b, an inverse in potency between the two isomers of 55 was observed wherein the (S)-isomer 55b was approximately 40-fold more potent than the (R)isomer 55a. An overall marked loss in activity was seen for both isomers of the p-CO2Me analogs in 56. The meta-biphenyl compound 57a was the most potent of the analogs tested with an EC50 of 5.9 nM, while a near-complete loss of activity was observed for its corresponding isomer 57b. Gratifyingly, none of the compounds tested showed any toxicity (EC50 > 10 µM) in a human PBMC viability assay.