Sulfonamide/sulfamate switch with a series of piperazinylureido derivatives: Synthesis, kinetic and in silico evaluation as carbonic anhydrase isoforms I, II, IV, and IX inhibitors

We report here a thorough structure-activity relationship (SAR) with piperazinylureido sulfamates as inhibitors of human (h) carbonic anhydrase (CA, EC 4.2.1.1). A SAR investigation over the structure of reported anti-cancer zinc-binder CAIs such as SLC-0111 and S4 was carried out by including the urea outer nitrogen atom into a substituted piperazine ring reducing the linker flexibility. The derivatives were assessed for the inhibition of CA I, II and IV (off-target isoforms) and the tumor-associated CA IX (anticancer drug target). CA I and IV were not effectively inhibited, whereas many low nanomolar inhibitors were evidenced against CA II (KIs in the range of 1.0–705.5 nM), and IX (KIs in the range of 0.91–155.9 nM). Interestingly, a subset of CA II/IX selective inhibitors was detected which might represent interesting lead for the development of new anticancer strategies.