Synthesis and evaluation of new Hsp90 inhibitors based on a 1,4,5-trisubstituted 1,2,3-triazole scaffold

Ruthenium catalyzed 1,3-cycloaddition (Click Chemistry) of an azido moiety installed on dihydroxycumene scaffold with differently substituted aryl propiolates gave a new family of 1,4,5-trisubstituted triazole carboxylic acid derivatives that showed high affinity toward HSP90 associated with cell proliferation inhibition, both in nanomolar range. The 1,5 arrangement of the resorcinol, the aryl moieties, and the presence of an alkyl (secondary) amide in position 4 of the triazole ring were essential to get high activity. Docking simulations suggested that the triazoles penetrate the HSP90 ATP binding site. Some 1,4,5-trisubstituted triazole carboxamides induced dramatic depletion of the examined client proteins and a very strong increase in the expression levels of the chaperone HSP70. In vitro metabolic stability and in vivo preliminary studies on selected compounds have shown promising results comparable to the potent HSP90 Inhibitor NVP-AUY922. One of them, (compound 18, SST0287CL1) was selected for further investigation as the most promising drug candidate.