Benzenesulfonamides functionalized with triazolyl-linked pyrazoles possess dual cathepsin B and carbonic anhydrase inhibitory action.

The design and synthesis of a library of 21 novel benzenesulfonamide-bearing 3-functionalized pyrazole-linked 1,2,3-triazole derivatives as dual inhibitors of cathepsin B and carbonic anhydrase enzymes are reported. The target 1,2,3-triazole-linked pyrazolic esters (16) were synthesized by the condensation of 1,2,3-triazolic diketo esters with 4-hydrazinobenzenesulfonamide hydrochloride, and these were further converted into the corresponding carboxylic acid (17) and carboxamide (18) analogs. The synthesized compounds were assayed in vitro for their inhibition potential against human carbonic anhydrase (hCA) isoforms I, II, IX, and XII. They were found to be potent inhibitors at the low nanomolar level against the cancer-related hCA IX and XII and to be selective towards the cytosolic isoform hCA I. The physiologically important isoform hCA II was potently inhibited by all the newly synthesized compounds showing KI values ranging between 0.8 and 561.5 nM. The ester derivative 16c having 4-fluorophenyl (KI = 5.2 nM) was the most potent inhibitor of hCA IX, and carboxamide derivative 18b (KI = 2.2 nM) having 4-methyl substituted phenyl was the most potent inhibitor of hCA XII. The newly synthesized compounds exhibited potent cathepsin B inhibition at 10-7 M concentration. In general, the carboxamide derivatives (18) showed higher % inhibition as compared with the corresponding ester derivatives (16) and carboxylic acid derivatives (17) for cathepsin B. The interactions of the target compounds with the active sites of cathepsin B and CA were studied through molecular docking studies. Further, the in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of the target compounds were also studied.

1,2,3-Triazole-based esters and carboxylic acids as nonclassical carbonic anhydrase inhibitors capable of cathepsin B inhibition.

Herein, we report the design and synthesis of a library of 28 new 1,2,3-triazole derivatives bearing carboxylic acid and ester moieties as dual inhibitors of carbonic anhydrase (CA) and cathepsin B enzymes. The synthesised compounds were assayed in vitro for their inhibition potential against four human CA (hCA) isoforms, I, II, IX and XII. The carboxylic acid derivatives displayed low micromolar inhibition against hCA II, IX and XII in contrast to the ester derivatives. Most of the target compounds showed poor inhibition against the hCA I isoform. 4-Fluorophenyl appended carboxylic acid derivative 6c was found to be the most potent inhibitor of hCA IX and hCA XII with a KI value of 0.7 µM for both the isoforms. The newly synthesised compounds showed dual inhibition towards CA as well as cathepsin B. The ester derivatives exhibited higher % inhibition at 10-7 M concentration as compared with the corresponding carboxylic acid derivatives against cathepsin B. The results from in silico studies of the target compounds with the active site of cathepsin B were found in good correlation with the in vitro results. Moreover, two compounds, 5i and 6c, showed cytotoxic activity against A549 lung cancer cells, with IC50 values lower than 100 µM.

Tail approach synthesis of triazolylthiazolotriazole bearing benzenesulfonamides as carbonic anhydrase inhibitors capable of inducing apoptosis.

Inhibition of human carbonic anhydrase (hCA) isoform IX with concurrent induction of apoptosis is a promising approach for targeting cancer in humans. Prompted by the scope, novel benzenesulfonamides containing the 1,2,3-triazolylthiazolotriazole tail were synthesized and screened as inhibitors of hCA isoforms I, II, IV, and IX. The tumor-associated isoform hCA IX was strongly inhibited by the sulfonamides reported here with KI values ranging from 45 nM to 1.882 µM. Overall, nine compounds showed hCA IX inhibition with KI < 250 nM. The glaucoma-associated isoform hCA II was moderately inhibited while the cytosolic isoform hCA I and membrane-bound isoform hCA IV were weakly inhibited by the synthesized sulfonamides. Compound 6Ac (KI = 3.6 nM) was found to be an almost three times more potent inhibitor of hCA II as compared to the standard drug acetazolamide (KI = 12.1 nM). The selective hCA IX inhibitors were further studied for their apoptotic efficacy in goat ovarian cells and showed better results as compared to the control. A comparative study of previously synthesized compounds and molecular docking study of representative compounds revealed some important generalizations that could prove beneficial in further investigations of isoform-selective hCA inhibitors.

A decade of tail-approach based design of selective as well as potent tumor associated carbonic anhydrase inhibitors.

Human carbonic anhydrase (hCA) isoforms hCA IX and hCA XII are well established anticancer drug targets and their selective inhibition is highly desired for the proper treatment of cancer. Lack of isoform-selectivity in current clinically used CA inhibitors (CAIs) is a major concern as it leads to undesired side effects, associated with off-target inhibition. Thus, there is need to explore alternative approaches for the design of isoform-selective inhibitors and the leading promising approach for the design of isoform-selective CAIs is "the tail-approach". Virtually, most drug design studies in the last decade were done by considering the tail-approach reported in 1999. The past decade of 2010-2020 witnessed progressive maturation of this approach as a large number of CAIs have been designed and synthesised based on it, many of which turned out to be effective as well as selective hCA IX and hCA XII inhibitors. This review covers the past decade (2010-2020) research, considering selective as well as potent inhibitors of tumor associated isoforms, hCA IX and hCA XII, which include newer generation inhibitors containing sulfonamides or their bioisosteres, non-classical inhibitors (including carboxylic acid/ester, coumarin and sulfocoumarin classes) and various other novel classes of inhibitors belonging to newly identified chemotypes/scaffolds.

Selective inhibition of carbonic anhydrase IX by sulphonylated 1,2,3-triazole incorporated benzenesulphonamides capable of inducing apoptosis.

In search of selective carbonic anhydrase (CA) IX inhibitors endowed with apoptotic inducing properties, we designed and synthesised two subsets of 4- and 3-(5-aryl-(4-phenylsulphonyl)-1H-1,2,3-triazol-1-yl)benzenesulphonamides. All compounds were assayed for human carbonic anhydrase (hCA) isoforms I, II, IV, and IX inhibition. Isoforms hCA I and hCA IV were weakly inhibited by most of the synthesised compounds. Many four-substituted benzenesulphonamides displayed low nanomolar inhibition against isoform hCA II, unlike the three-substituted analogues. All target compounds exhibited good inhibition profile with KI values ranging from 16.4 to 66.0 nM against tumour-associated isoform hCA IX. Some selective and potent inhibitors of hCA IX were assayed for in vitro apoptotic induction in goat testicular cells. Compounds 10d and 10h showed interesting apoptotic induction potential. The present study may provide insights into a strategy for the design of novel anticancer agents based on hCA inhibitors endowed with apoptotic interference.

Tail-approach based design and synthesis of Arylthiazolylhydrazono-1,2,3-triazoles incorporating sulfanilamide and metanilamide as human carbonic anhydrase I, II, IV and IX inhibitors.

A library of twenty-two arylthiazolylhydrazono-1,2,3-triazoles incorporating sulfanilamide and metanilamide moieties have been synthesized by utilizing tail-approach and characterized by their IR, 1H NMR, 13C NMR, HRMS and single crystal studies. Further, these newly synthesized compounds were screened in-vitro for their inhibition efficacy against physiologically relevant hCA I, II, IV and IX isoforms. Inhibition data revealed that, in broader sense, sulfanilamide analogues (4a-4k) were comparatively better inhibitors of cytosolic hCA I and II isoforms than metanilamide analogues (5a-5k), whereas exactly opposite trend was observed in case of inhibition of membrane bound hCA IV and transmembrane hCA IX. For hCA I, more than half of the synthesized compounds were found to be moderate inhibitors and three compounds 4b, 5b and 5e (Ki of 40.6, 224.7 and 74.4 nM, respectively) appeared as better inhibitors than reference drug AAZ (Ki = 250 nM). hCA II was potently inhibited by 4e-4g and 5e with Ki of 18.1, 14.1, 14.9 and 17.8 nM, respectively. Interestingly, 4e-4g selectively inhibited hCA II with selectivity of > 15-fold over hCA I, IV and IX isoforms. All the compounds presented moderate to weak inhibition profiles against glaucoma associated hCA IV with Ki of 88 nM-8.87 µM and except 4f, 5k, significant inhibition profiles against tumor associated hCA IX isoform with Ki spanning in range of 0.113 µM-0.318 µM. Moreover, 5e was the only compound among the whole series which effectively inhibited all the tested isoforms.