The structures of small molecules that activate or inhibit Hedgehog (Hh) signaling. (a) The leiosamine family of compounds that activate Hh signaling by binding to Smoothened. Hh-Ag (Hedgehog agonist) 1.1 was the original compound identified in the high-throughput screen by Frank-Kamenetsky et al., with an EC50 of 3 μM in their luciferase reporter assay. Hh-Ag 1.2 is a more potent derivative that is also characterized by Chen et al., who refer to it as SAG for 'synthetic Hh agonist'. Hh-Ag 1.5 is the most potent Hh agonist reported , with an E50 of 1 nM. (b) The structures of two compounds that bind to Smoothened to inhibit Hh signaling, cyclopamine and Cur61414. Structurally distinct classes of Smoothened antagonists have also been reported  but are not shown here.
King Journal of Biology 2002 1:8 doi:10.1186/1475-4924-1-8