A new series of phosphonate side chain analogues of 1 alpha,25-dihydroxyvit
amin D-3 (1) have been synthesized. Antiproliferative activities of theses
analogues (8a,b and 9a,b) using human keratinocyte cell shows that analogue
s which have natural A-ring show higher activity than unnatural A-ring seri
es and almost equally active to 1 alpha,25-Dihydroxyvitamin D-3 (1) at 1 mu
M level.