Small molecule Hedgehog pathway antagonists

Leveraging our quinolone-1-(2H)-one based Hedgehog signalling pathway (HSP) inhibitors we have developed two new classes of HSP inhibitors based on: l-tryptophan and benzo[1,3]dioxol-5-ylmethyl-[2-(1H-indol-3-yl)-ethyl]-amine. Synthesis of focused compound libraries identified six l-tryptophan based inhibitors, and two stimulators, of Gli at 10 μM compound concentration. 2,4-Dichloro-13 and indole 16 suppressed mRNA expression of Ptch₁ in Shh LIGHT2 cells, with 13 suppressing and 16 stimulating Gli₂ mRNA expression. Focused library development of the benzo[1,3]dioxol-5-ylmethyl-[2-(1H-indol-3-yl)-ethyl]-amine scaffold afforded two sub-micro molar potent inhibitors of Gli expression with 5-methoxy-1H-indole-2-carboxylic acid benzo[1,3]dioxol-5-ylmethyl-[2-(1H-indol-3-yl)-ethyl]-amide 29 and 5-chloro-1H-indole-2-carboxylic acid benzo[1,3]dioxol-5-ylmethyl-[2-(1H-indol-3-yl)-ethyl]-amide 30 returning IC₅₀ values of 0.5 and 0.24 μM, respectively. Neither 29 nor 30 acted directly on Smo with our data supporting inhibition of the HSP downstream of Smo.