Highly hydrophilic 1,3-oxazol-5-yl benzenesulfonamide inhibitors of carbonic anhydrase II for reduction of glaucoma-related intraocular pressure

5-(Sulfamoyl)thien-2-yl 1,3-oxazole inhibitors of carbonic anhydrase II with hydrophilic periphery

Hydrophilic derivatives of an earlier described series of carbonic anhydrase inhibitors have been designed, prepared and profiled against a panel of carbonic anhydrase isoforms, including the glaucoma-related hCA II. For all hydrophilic derivatives, computational prediction of intraocular permeability routes showed the predominance of conjunctival rather than corneal absorption. The potentially reactive primary or secondary amine periphery of these compounds makes them suitable candidates for bioconjugation to polymeric drug carriers. As was shown previously, the most active hCA II inhibitor is efficacious in alleviating intraocular pressure in normotensive rabbits with efficacy matching that of dorzolamide.

Discovery of novel aminosaccharide-based sulfonamide derivatives as potential carbonic anhydrase II inhibitors

In this paper, a new class of novel sulfonamides incorporating aminosaccharide tails were designed and synthesized based on the sugar-tail approach. Then, all the novel compounds were evaluated for their inhibitory activities against three carbonic anhydrase (CA, EC 4.2.1.1) isoenzymes (hCA I, hCA II and hCA IX). Interestingly, effective inhibition of these three CA isoforms were observed, especially the glaucoma associated isoform hCA II. It is worth noting that these glycoconjugated sulfonamide derivatives also showed better CA inhibitory effects compared to the initial segment carzenide. Among them, compound 8d was the most effective inhibitor with IC₅₀ of 60 nM against hCA II. Subsequent physicochemical properties studies showed that all compounds have good water solubility and neutral pH values in solutions. And these important physicochemical properties make target compounds acquire obvious advantages in the preparation of topical and nonirritating antiglaucoma drugs. Moreover, the target compounds showed lower corneal cytotoxicity than acetazolamide (AAZ) and good metabolic stability in vitro. In addition, molecular docking studies confirmed the interactions between aminosaccharide fragment and hydrophilic subpocket of hCA II active site were crucial for the enhanced CA inhibitory activity. Taken together, these results suggested 8d would be a promising lead compound for the development of topical antiglaucoma CAIs.

Mucoadhesive properties of nanogels based on stimuli-sensitive glycosaminoglycan-graft-pNIPAAm copolymers

Mucoadhesive formulations capable of situ gelation are promising for improving ocular drug delivery. Here we investigated two types of nanogels based on anionic glycosaminoglycans with grafted thermo-responsive poly(N-isopropylacrylamide) chains. One type of nanogels were formed by thermo-induced gelling of heparin-graft-poly(N-isopropylacrylamide) and chondroitin sulfate-graft-poly(N-isopropylacrylamide) copolymers. Another type of nanogels was based on the same copolymers, but terminal groups of thermosensitive macromolecular chains were modified to form covalent disulfide cross-links. All types of nanogels were studied towards their ability to encapsulate and release model drug - dexamethasone. Mucoadhesivity of both thermo-gelled and covalently cross-linked polymeric systems, as well as their ability to interact with dexamethasone, was assessed by microscale thermophoresis (MST). Mucoadhesion properties were also evaluated by isothermal titration calorimetry (ITC), which were in good correlation with MST data. The presence of disulfide linkages and thiol groups were shown to favor improved binding of cross-linked nanogels to mucin. Moreover, in vivo intraocular pressure studies showed that presence of polymers in solution can alter the ocular absorption of carbonic anhydrase inhibitor from eyedrops. The pharmacological effect was in line with mucoadhesive properties of these copolymers.

Constitutional Dynamic Inhibition/Activation of Carbonic Anhydrases

In this review we consider one important member of the metalloenzymes family, the carbonic anhydrase (CA), involved in the treatment of several common diseases. Different approaches have emerged to regulate the activity of CA, mostly acting on the inner catalytic active site or outer microenvironment of the enzyme, leading to inhibition or activation of CA. In recent years, gradually increased attention has focused on the adoption of constitutional dynamic chemistry (CDC) strategies for the screening and discovery of potent inhibitors or activators. The participation of reversible covalent bonds enabled the enzyme itself to select the optimal ligands obtained from diverse building blocks with comparatively higher degree of variety, resulting in the fittest recognition of enzyme ligands from complex dynamic systems. With the increasing implementation of CDC for enzyme targets, it shows great potential for drug discovery or CO₂ capture applications.

Investigation of 3-sulfamoyl coumarins against cancer-related IX and XII isoforms of human carbonic anhydrase as well as cancer cells leads to the discovery of 2-oxo-2H-benzo[h]chromene-3-sulfonamide - A new caspase-activating proapoptotic agent

Herein we report the synthesis of a set of seventeen 3-sulfonamide substituted coumarin derivatives. Prepared compounds were tested in vitro for inhibition of four physiologically relevant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Several coumarin sulfonamides displayed low nanomolar K_I values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Some of these compounds exerted a concentration-dependent antiproliferative action toward RT4 human bladder cancer and especially A431 human epidermoid carcinoma cell lines. In the meantime, the viability of non-tumorigenic hTERT immortalized human foreskin fibroblast cell line Bj-5ta was not significantly affected by the obtained derivatives. Interestingly, compound 10q (2-oxo-2H-benzo [h]chromene-3-sulfonamide) showed a profound and selective dose-dependent inhibition of A431 cell growth with low nanomolar IC₅₀ values. We demonstrated that 10q possessed a concentration-dependent apoptosis induction activity associated with caspase 3/7 activation in cancer cells. As carbonic anhydrase isoforms in question were not potently inhibited by this compound, its antiproliferative effects likely involve other mechanisms, such as DNA intercalation. Compound 10q clearly represents a viable lead for further development of new-generation anticancer agents.

Insertion of metal carbenes into the anilinic N-H bond of unprotected aminobenzenesulfonamides delivers low nanomolar inhibitors of human carbonic anhydrase IX and XII isoforms

Herein we report the synthesis of a set of thirty-four primary sulfonamides generated via formal N-H-insertion of metal carbenes into anilinic amino group of sulfanilamide and its meta-substituted analog. Obtained compounds were tested in vitro as inhibitors of four physiologically significant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Many of the synthesized sulfonamides displayed low nanomolar K_i values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Provided the promising activity profiles of the substances towards tumor-associated hCA IX and XII isozymes, single-concentration MTT test was performed for the entire set. Disappointingly, most of the discovered hCA inhibitors did not significantly suppress the growth of cancer cells either in normoxia or CoCl₂ induced hypoxic conditions. The only two compounds exerting profound antiproliferative effect turned out to be modest hCA inhibitors. Their out of the range activity in cells is likely attributive to the presence of Michael acceptor substructure which can potentially act either through the inhibition of Thioredoxin reductases (TrxRs, EC 1.8.1.9) or nonspecific covalent binding to cell proteins.

Incorporation of ion exchange functionalized-montmorillonite into solid lipid nanoparticles with low irritation enhances drug bioavailability for glaucoma treatment

Montmorillonite-loaded solid lipid nanoparticles with good biocompatibility, using Betaxolol hydrochloride as model drug, were prepared by the melt-emulsion sonication and low temperature-solidification methods and drug bioavailability was significantly improved in this paper for the first time to application to the eye. The appropriate physical characteristics were showed, such as the mean particle size, Zeta potential, osmotic pressure, pH values, entrapping efficiency (EE%) and drug content (DC%), all showed well suited for possible ocular application. In vitro release experiment indicated that this novel system could continuously release 57.83% drugs within 12 h owing to the dual drug controlled-release effect that was achieved by ion-exchange feature of montmorillonite and structure of solid lipid nanoparticles. Low irritability and good compatibility of nanoparticles were proved by both CAM-TBS test and cytotoxicity experiment. We first discovered from the results of Rose Bengal experiment that the hydrophilicity of the drug-loaded nanoparticles surface was increased during the loading and releasing of the hydrophilic drug, which could contribute to prolong the ocular surface retention time of drug in the biological interface membrane of tear-film/cornea. The results of in vivo pharmacokinetic and pharmacodynamics studies further confirmed that increased hydrophilicity of nanoparticles surface help to improve the bioavailability of the drug and reduce intraocular pressure during administration. The results suggested this novel drug delivery system could be potentially used as an in situ drug controlled-release system for ophthalmic delivery to enhance the bioavailability and efficacy.