Thienothiopyransulfonamides as complexing agents for the preparation of dual carbonic anhydrase inhibitors

Co(II); Zn(II) and Cu(II) complexes of two new sulfonamide carbonic anhydrase (CA) inhibitors, derivatives of thienothiopyran-2-sulfonamide, were prepared and characterized by analytic, spectroscopic, magnetic and conductimetric measurements. The new complexes are more potent CA inhibitors than the parent sulfonamides, with IC(50) values around 0.1 nM, against isozyme CA II.     

Complexes with biologically active ligands. Part 4. Coordination compounds of chlorothiazide with transition metal ions behave as strong carbonic anhydrase inhibitors

Complexes of the diuretic benzothiadiazine derivative chlorothiazide (6-chloro-7-sulfamoyl- 1,2,4-benzothiadiazine-1,1-dioxide) with V(IV); Fe(II); Co(II); Ni(II); Cu(II), Ag(I) and U(VI) were prepared and characterized by elemental analysis, spectroscopic, thermogravimetric, magnetic and conductimetric measurements. The complexes behave as effective inhibitors for two isozymes (I and II) of carbonic anhydrase (CA).     

Complexes with biologically active ligands. Part 11. Synthesis and carbonic anhydrase inhibitory activity of metal complexes of 4,5-disubstituted-3-mercapto-1,2,4-triazole derivatives

Complexes containing five 4,5-disubstituted-3-mercapto-1,2,4-triazoles and Zn(II), Hg(II) and Cu(I) were synthesized and characterized by standard procedures (elemental analysis; IR, electronic and NMR spectroscopy, conductimetry and TG analysis). Both the thione as well as the thiolate forms of the ligands were evidenced to interact with the metal ions in the prepared complexes. The original mercaptans and their metal complexes behave as inhibitors of three carbonic anhydrase (CA) isozymes, CA I, II and IV, but did not lower intraocular pressure in rabbits in animal models of glaucoma.     

Carbonic Anhydrase Inhibitors. Part 46 Inhibition of Carbonic Anhydrase Isozymes I, II and IV With Trifluoromethylsulfonamide Derivatives and Their Zinc(II) and Copper(II) Complexes

Reaction of aromatic/heterocyclic sulfonamides containing a free amino group with triflic anhydride afforded compounds possessing trifluoromethanesulfonamido moieties in their molecule. The Zn(II) and Cu(II) complexes of these new sulfonamides were prepared and characterized by standard procedures (elemental analysis, spectroscopic, magnetic, thermogravimetric and conductimetric measurements). The new derivatives showed good inhibitory activity against three isozymes of carbonic anhydrase (CA), i.e., CA I, II and IV.     

Carbonic Anhydrase Inhibitors Part 72 Synthesis and Antiglaucoma Properties of Metal Complexes of p-Fluorobenzolamide

Metal complexes of a heterocyclic sulfonamides possessing very strong carbonic anhydrase (CA) inhibitory properties, i.e., 5-(p-fluorobenzenesulfonylamido)-1,3,4-thiadiazole-2-sulfonamide (p-fluorobenzolamide) were prepared. The new complexes contained metal ions such as Zn(II), Cu(II), Co(II), Ni(II), Cd(II) and Mn(II). The new compounds were characterized by standard physico-chemical procedures, and assayed as inhibitors of three CA isozymes, CA I, II and IV. Very good inhibition has been evidenced both for the parent sulfonamides as well as for the prepared complexes, against all three investigated isozymes. Some of these new complexes as well as the parent sulfonamide, strongly lowered intraocular pressure (IOP) in normotensive rabbits when administered as a 2% solution into the eye.     

Complexes with biologically active ligands. Part 9 metal complexes of 5-benzoylamino- and 5-(3-nitrobenzoyl-amino)-1,3,4-thiadiazole-2-sulfonamide as carbonic anhydrase inhibitors

Complexes containing the anions of 5-benzoylamido-1,3,4-thiadiazole-2-sulfonamide and 5-(3-nitro-benzoylamido)-1,3,4-thiadiazole-2-sulfonamid as ligands, and V(IV); Cr(III); Fe(III); Co(II); Ni(II); Cu(II) and Ag(I) were synthesized and characterized by standard procedures (elemental analysis; IR, electronic, and EPR spectroscopy; TG, magnetic and conductimetric measurements). The original sulfonamides and their metal complexes are strong inhibitors of two carbonic anhydrase (CA) isozymes, CA I and II.     

Carbonic anhydrase inhibitors. Part 54: metal complexes of heterocyclic sulfonamides: a new class of antiglaucoma agents

Metal complexes of heterocyclic sulfonamides possessing carbonic anhydrase (CA) inhibitory properties were recently shown to be useful as intraocular pressure (IOP) lowering agents in experimental animals, and might be developed as a novel class of antiglaucoma drugs. Here we report the synthesis of a heterocyclic sulfonamide CA inhibitor and of the metal complexes containing main group metal ions, such as Be(II), Mg(II), Al(III), Zn(II), Cd(II) and Hg(II) and the new sulfonamide as well as 5-amino-1,3,4-thiadiazole-2-sulfonamide as ligands. The new complexes were characterized by standard physico-chemical procedures, and assayed as inhibitors of three CA isozymes, CA I, II and IV. Some of them (but not the parent sulfonamides) strongly lowered IOP in rabbits when administered as a 2% solution into the eye.     

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.     

Complexes with biologically active ligands. Part 1. Synthesis of coordination compounds of diazoxide with transition- and main-group cations

Complexes of diazoxide (3-methyl-7-chloro-1,2,4-benzothiadiazine-1,1-dioxide) - an antihypertensive and hyperglycemic pharmacological agent - with a series of transition- and main-group di-, triand tetravalent metal ions were prepared and characterized by elemental analysis, spectroscopic, thermogravimetric, magnetic and conductimetric measurements. The complexes were tested as inhibitors of the enzyme carbonic anhydrase (CA), proving modest activity towards CA II and better inhibition of CA I.     

Complexes With Biologically Active Ligands. Part 10 Inhibition of Carbonic Anhydrase Isozymes I and II With Metal Complexes of Imidazo[2,1-b ]-1,3,4-Thiadiazole-2-Sulfonamide

THE TITLE COMPOUND WAS PREPARED BY AN IMPROVED VARIANT OF THE LITERATURE PROCEDURE, AND METAL COMPLEXES CONTAINING ITS ANION AND THE FOLLOWING METAL IONS: Zn(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II), V(IV), Fe(III) and Ag(I) were synthesized and characterized by standard procedures (elemental analysis; IR, electronic, NMR and EPR spectroscopy; TG, magnetic and conductimetric measurements). The parent sulfonamide and its metal complexes are potent inhibitors of two carbonic anhydrase (CA) isozymes, CA I and II, and they might possess applications as selective cerebrovasodilating agents.     

Complexes With Biologically Active Ligands. Part 2. Preparation of Copper(II) Complexes of Positively-Charged Derivatives of Aminoglutethimide

Cu(II) complexes of 1-[4-(3-ethyl-piperidine-2,6-dione)-3-yl]-phenyl-2,4,6-trisubstituted pyridinium perchlorates, containing alkyl, aryl and combinations of these two types of moieties in their molecule were synthesized and characterized by elemental analysis, spectroscopy, magnetic, thermogravimetric and conductimetric measurements. In these complexes, Cu(II) ions are in octahedral geometry with four water molecules occupying the equatorial coordination sites and the two organic ligands in deprotonated state the remaining axial ones. The donor atom of these ligands is constituted by the ionized nitrogen of the glutarimide moiety. The new derivatives possess weak inhibitory activity towards the zinc enzyme carbonic anhydrase.     

Carbonic Anhydrase Inhibitors. Part 55 Metal Complexes of 1,3,4-Thiadiazole-2-Sulfonamide Derivatives: In Vitro Inhibition Studies With Carbonic Anhydrase Isozymes I, II and IV

Coordination compounds of 5-chloroacetamido-1,3,4-thiadiazole-2-sulfonamide (Hcaz) with V(IV), Cr(lll), Fe(ll), Co(ll), Ni(ll) and Cu(ll) have been prepared and characterized by standard procedures (spectroscopic, magnetic, EPR, thermogravimetric and conductimetric measurements). Some of these compounds showed very good in vitro inhibitory properties against three physiologically relevant carbonic anhydrase (CA)isozymes, i.e., CA I, II, and IV. The differences between these isozymes in susceptibility to inhibition by these metal complexes is discussed in relationship to the characteristic features of their active sites, and is rationalized in terms useful for developing isozyme-specific CA inhibitors.     

Model studies for molecular recognition of carbonic anhydrase and carboxypeptidase

Model studies using Zn(2+) complexes of various derivatives of macrocyclic triamines ([12]aneN(3)) and tetraamines (cyclen) have been found to be useful in elucidating and understanding the intrinsic properties of substrate or inhibitor recognition by zinc ions at the active centers of carbonic anhydrase and carboxypeptidase.     

CO2 sequestration using principles of shell formation

Biomimetic sequestration of carbon dioxide (CO₂) is one of the methods proposed to reduce the CO₂ released into the atmosphere. In this study, we compared soluble protein of hemocyte from diseased shell (HDS) and extrapallial fluid (EPF) extracted from Crassostrea gigas with bovine carbonic anhydrase II in terms of their ability to promote CO₂ hydration and the production of calcium precipitates. On the basis of the experiments of CO₂ hydration, the key role of HDS was identified. Moreover, mass‐spectroscopic analysis (MALDI‐TOF) and circular dichroism (CD) analysis were used for understanding molecular weight and secondary protein structure. From the amino acid sequence and secondary protein structure, the different processes of CO₂ hydration by bovine carbonic anhydrase II and HDS could be assessed.     

微生物碳酸酐酶在岩溶发育中的研究现状及展望

碳酸酐酶是生物体中普遍存在的一种金属酶,能催化CO<,2>可逆的水合反应,微生物是碳酸酐酶的重要来源之一.综述了国内外微生物碳酸酐酶在岩溶发育中的研究现状,阐述了碳酸酐酶对碳循环的影响及其在石漠化治理中的作用,并对微生物碳酸酐酶在岩溶发育中的研究进行了展望.     

Metal Complexes of 1,3,4-Thiadiazole-2,5-Disulfonamide are Strong Dual Carbonic Anhydrase Inhibitors, although the Ligand Possesses very Weak such Properties

Coordination compounds of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with 1,3,4-thiadiazole-2,5-disulfonamide as ligand were synthesized and characterized by IR and UV spectroscopy, conductimetry and thermogravimetry. The parent ligand is a very weak carbonic anhydrase (CA) inhibitor, although it constituted the lead for developing important classes of diuretics. The complex derivatives behave as much stronger CA inhibitors, with IC(50) values around 10(-8)M against isozyme CA II, and 10(-7) M against isozyme CAI.     

Synthesis and Biological Evaluation of 4‐Sulfamoylphenyl/Sulfocoumarin Carboxamides as Selective Inhibitors of Carbonic Anhydrase Isoforms hCA II,IX, and XII

With the aim to develop potent and selective human carbonic anhydrase inhibitors (hCAIs), we synthesized 4‐sulfamoylphenyl/sulfocoumarin benzamides (series 5 a – r and series 7 a – q ) and evaluated their inhibition profiles against five isoforms of the zinc‐containing human carbonic anhydrase (hCA, EC 4.2.1.1): cytosolic hCA I and II, and the transmembrane isozymes hCA IV, IX, and XII. Compounds 5 a – r were found to selectively inhibit hCA II in the nanomolar range, while being less effective against the other hCA isoforms. As noted from the literature, sulfocoumarin (1,2‐benzoxathiine 2,2‐dioxide) acts as a “prodrug” inhibitor and is hydrolyzed by the esterase activity of hCA to form 2‐hydroxyphenylvinylsulfonic acid, which thereafter binds to the enzyme in a manner similar to that of coumarins and sulfoxocoumarins. All these sulfocoumarins (compounds 7 a – q ) were found to be very weak or ineffective as inhibitors of the housekeeping off‐target hCA isoforms I and II, and effectively inhibited the transmembrane tumor‐associated isoforms IX and XII in the high nanomolar to micromolar ranges. Further structural modifications of these molecules could be useful for the development of effective hCA inhibitors used for the treatment of glaucoma, epilepsy, and cancer.     

水化层影响酸酐酶内CO2扩散行为的分子动力学模拟

气相中酶分子表面的水化层对其催化行为具有显著的影响。本文采用全原子分子动力学模拟方法考察了气相体系碳酸酐酶表面的水化层对酶结构以及CO₂在酶分子中扩散行为的影响。首先展现了水分子在酶分子及其活性中心周围的分布,研究了水化层厚度对于酶结构以及CO₂扩散速率的影响;发现最有利于CO₂扩散进入酶分子的水化层厚度为0.7 nm。确认了碳酸酐酶内CO₂的吸附位点,通过对其开合状态统计,显示出碳酸酐酶中CO₂扩散通道中的瓶颈位置。上述结果对设计和优化碳酸酐酶催化气相体系中CO₂的吸附和转化提供了依据和启示。     

Polypeptide conjugate binders that discriminate between two isoforms of human carbonic anhydrase in human blood

Two binder candidates 4‐C37L34‐B and 3‐C15L8‐B from a 16‐membered set of 42‐residue polypeptide conjugates designed to bind human carbonic anhydrase II (HCAII), were shown to bind HCAII with high affinity in a fluorescence‐based screening assay. Two carbonic anhydrase isoforms with 60 % homology exist in human blood with HCAI being present in five‐ to sevenfold excess over HCAII. The ability of the binders to discriminate between HCAI and HCAII was evaluated with regard to what selectivity could be achieved by the conjugation of polypeptides from a 16‐membered set to a small organic molecule that binds both isoforms with similar affinities. The polypeptide conjugate 4‐C37L34‐B bound HCAII with a K_D of 17 nM and HCAI with a K_D of 470 nM , that is, with a 30‐fold difference in affinity. The corresponding dissociation constants for the complexes formed from 3‐C15L8‐B and the two carbonic anhydrases were 60 and 390 nM , respectively. This demonstration of selectivity between two very similar proteins is striking in view of the fact that the molecular weight of each one of the conjugate molecules is little more than 5000, the fold is unordered, and the polypeptide sequences were designed de novo and have no prior relationship to carbonic anhydrases. The results suggest that synthetic polypeptide conjugates can be prepared from organic molecules that are considered to be weak binders with low selectivity, yielding conjugates with properties that make them attractive alternatives to biologically generated binders in biotechnology and biomedicine.     

Carbonic anhydrase inhibitors: design of membrane-impermeant copper(II) complexes of DTPA-, DOTA-, and TETA-tailed sulfonamides targeting the tumor-associated transmembrane isoform IX

The synthesis and carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of two series of aromatic sulfonamides and their Cu(II) derivatives, incorporating metal-complexing moieties of the DTPA, DOTA, and TETA type are reported. The new compounds were designed in such a way as to possess high affinity for Cu(II) ions, exploiting four pendant carboxylate moieties in the DTPA derivatives, as well as the cyclen/cyclam macrocyles, and three pendant acetate moieties in the DOTA and TETA derivatives. The new derivatives showed modest inhibition of the cytosolic isoform CA I (K(I) values in the range of 66-2130 nM), were better CA II inhibitors (K(I) values in the range of 21-360 nM), and excellent inhibitors of the tumor-associated isoform CA IX (K(I) values in the range of 4.1-110 nM), with selectivity ratios for the inhibition of the tumor (CA IX) over the cytosolic (CA II) isozyme in the range of 10.74-20.88 for the best derivatives. Copper complexes were more inhibitory than the corresponding ligand sulfonamides, and showed membrane impermeability, thus, having the possibility to specifically target the transmembrane CA IX that has an extracellular active site. Incorporation of radioactive copper isotopes in this type of CA inhibitor may lead to interesting diagnostic/therapeutic applications for such compounds.