5-[2-(N-(Substituted phenyl)acetamide)]amino-1,3,4-thiadiazole-2-sulfonamides as Selective Carbonic Anhydrase II Inhibitors with Neuroprotective Effects

In this study, 22 novel compounds were designed and synthesized by acetamide bridge chains, among which 5 a-5 k were monosubstituted compounds, and 6 a-6 k were disubstituted. A series of biological evaluations was then carried out to determine the carbonic anhydrase inhibitory activity, neuroprotective effects and cytotoxicity of 5 a-5 k and 6 a-6 k. The results showed that some compounds could protect PC12 cells from sodium nitroprusside (SNP)-induced damage. In terms of the neuroprotection and inhibitory activity against carbonic anhydrase II, monosubstituted compounds were better than disubstituted. Compound 5 c exhibited better protective effect in PC12 cells than that of edaravone, and 5 c also showed less cytotoxicity. In addition, compound 5 c was found to be the most effective selective carbonic anhydrase II inhibitor (IC50=16.7 nM, CAI/CAII=54.3), which was similar to the inhibitory effect of acetazolamide. Moreover, the selectivity of compound 5 c was better than that of acetazolamide (IC50=12.0 nM, CAI/CAII=20.8). Molecular docking presented that the binding effect of compound 5 c with carbonic anhydrase II was superior to that of 5 c with carbonic anhydrase I and IX, which was consistent with the inhibitory results. Based on above findings, compound 5 c may be a potential candidate for selective carbonic anhydrase II inhibitor, and it had obviously neuroprotective effect and great advantages in drug safety.