Cyclopamine analogs bearing exocyclic methylenes are highly potent and acid-stable inhibitors of hedgehog signaling.

The chemical synthesis and biological evaluation of new cyclopamine analogs bearing exocyclic methylenes in different positions is described. Bis-exo-cyclopamine 6 was identified as a potent inhibitor of the Gli1-dependent luciferase expression in Shh-LIGHTII cells. An extension of this study to F-ring-modified structures shows the necessity of a rigidly positioned nitrogen atom for bioactivity as well as the presence of the C21 methyl group for acid stability and bioactivity.

Potent small molecule Hedgehog agonists induce VEGF expression in vitro.

Here, we describe the synthesis, SAR studies as well as biological investigations of the known Hedgehog signaling agonist SAG and a small library of its analogues. The SAG and its derivatives were analyzed for their potency to activate the expression of the Hh target gene Gli1 in a reporter gene assay. By analyzing SAR important molecular descriptors for Gli1 activation have been identified. SAG as well as compound 10c proven to be potent activators of VEGF expression in cultivated dermal fibroblasts. Importantly and in contrast to SAG, derivative 10c displayed no toxicity in concentrations up to 250 µm.