Structural development of p-carborane-based potent non-secosteroidal vitamin D analogs.

Non-secosteroidal vitamin D receptor (VDR) ligands are promising candidates for many clinical applications. We recently developed novel non-secosteroidal VDR agonists based on p-carborane (an icosahedral carbon-containing boron cluster) as a hydrophobic core structure. Here, we report the design, synthesis and biological evaluation of carborane-based vitamin D analogs bearing various substituents at the diol moiety. Among the synthesized compounds, methylene derivative 31 exhibited the most potent vitamin D activity, which was comparable to that of the natural hormone, 1α,25(OH)2D3. This compound is one of the most potent non-secosteroidal VDR agonists reported to date, and is a promising lead for development of novel drug candidates.