Pyrrolidinone-bearing methylated and halogenated benzenesulfonamides as inhibitors of carbonic anhydrases

Two series of benzenesulfonamides bearing methyl groups at ortho/ortho or meta/ortho positions and a pyrrolidinone moiety at para position were synthesized and tested as inhibitors of the twelve catalytically active human carbonic anhydrase (CA) isoforms. Observed binding affinities were determined by fluorescent thermal shift assay and intrinsic binding affinities representing the binding of benzenesulfonamide anion to the Zn(II)-bound water form of CA were calculated. Introduction of dimethyl groups into benzenesulfonamide ring decreased the binding affinity to almost all CA isoforms, but gained in selectivity towards one CA isoform. A chloro group at the meta position of 2,6-dimethylbenzenesulfonamide derivatives did not influence the binding to CA I, but it increased the affinity to all other CAs, especially, CA VII and CA XIII (up to 500 fold). The compounds may be used for further development of CA inhibitors with higher selectivity to particular CA isoforms.     

Benzenesulfonamides with benzimidazole moieties as inhibitors of carbonic anhydrases I,II, VII,XII and XIII

Abstract

A series of benzenesulfonamide derivatives, bearing benzimidazole moieties, were designed and synthesized as inhibitors of carbonic anhydrases (CAs). Their binding affinities to recombinant human CA isozymes I, II, VII, XII and XIII were determined by the thermal shift assay. A group of compounds containing a benzimidazole substituent in the para position of the benzenesulfonamide ring was found to exhibit higher binding potency toward tested CAs than meta-substituted benzenesulfonamides. Some of these compounds exhibited nanomolar affinities and selectivity toward the CA isozymes tested.     

N-Sulfamoylphenyl- and N-sulfamoylphenyl-N-thiazolyl-β-alanines and their derivatives as inhibitors of human carbonic anhydrases

A series of N-substituted and N,N-disubstituted β-amino acids and their derivatives bearing benzenesulfonamide moiety were designed and synthesized in search of compounds that would be high-affinity and selective inhibitors of human carbonic anhydrases (CA). There are 12 catalytically active human CA isoforms, the cytosolic CA I, CA II, CA III, CA VII, and CA XIII, secreted CA VI, the mitochondrial CA VA and CA VB, membrane-associated CA IV, and transmembrane CA IX, CA XII, and CA XIV. The di-bromo meta-substituted compounds exhibited low nanomolar dissociation constants and over 10-fold selectivity for mitochondrial isozyme CA VB, implicated in diseases of the central nervous system and obesity. These compounds can be used for further development as inhibitors of significant binding affinity and selectivity towards CA VB isozyme.     

Benzenesulfonamides with pyrimidine moiety as inhibitors of human carbonic anhydrases I,II, VI,VII, XII,and XIII

Two groups of benzenesulfonamide derivatives, bearing pyrimidine moieties, were designed and synthesized as inhibitors of carbonic anhydrases (CA). Their binding affinities to six recombinant human CA isoforms I, II, VI, VII, XII, and XIII were determined by the thermal shift assay (TSA). The binding of several inhibitors was measured by isothermal titration calorimetry (ITC). Direct demonstration of compound inhibition was achieved by determining the inhibition constant by stopped-flow CO₂ hydration assay. The most potent compounds demonstrated selectivity towards isoform I and affinities of 0.5 nM. The crystal structures of selected compounds in complex with CA II, XII, and XIII were determined to atomic resolution. Compounds described here were compared with previously published pyrimidinebenzenesulfonamides.¹ Systematic structure–activity analysis of 40 compound interactions with six isoforms yields clues for the design of compounds with greater affinities and selectivities towards target CA isoforms.     

Intrinsic thermodynamics of inhibitor binding to human carbonic anhydrase IX

BackgroundHuman carbonic anhydrase 9th isoform (CA IX) is an important marker of numerous cancers and is increasingly interesting as a potential anticancer drug target. Various synthetic aromatic sulfonamide-bearing compounds are being designed as potent inhibitors of CA IX. However, sulfonamide compound binding to CA IX is linked to several reactions, the deprotonation of the sulfonamide amino group and the protonation of the CA active site Zn(II)-bound hydroxide. These linked reactions significantly affect the affinities and other thermodynamic parameters such as enthalpies and entropies of binding.MethodsThe observed and intrinsic affinities of compound binding to CA IX were determined by the fluorescent thermal shift assay. The enthalpies and entropies of binding were determined by the isothermal titration calorimetry.ResultsThe pK_a of CA IX was determined to be 6.8 and the enthalpy of CA IX-Zn(II)-bound hydroxide protonation was − 24 kJ/mol. These values enabled the analysis of intrinsic thermodynamics of a library of compounds binding to CA IX. The most strongly binding compounds exhibited the intrinsic affinity of 0.01 nM and the observed affinity of 2 nM.ConclusionsThe intrinsic thermodynamic parameters of compound binding to CA IX helped to draw the compound structure to thermodynamics relationship.General significanceIt is important to distinguish the intrinsic from observed parameters of any disease target protein interaction with its inhibitors as drug candidates when drawing detailed compound structure to thermodynamics correlations.     

Synthesis,characterization, in vitro cytotoxicity and antimicrobial investigation and evaluation of physicochemical properties of novel 4-(2-methylacetamide)benzenesulfonamide derivatives

In this study, several sulfonamide derivatives, 4-(2-methylacetylamino)benzenesulfonamides were synthesized. Chemical structures of the derivatives were characterized by ¹H NMR, ¹³C NMR, LC–MS–MS, UV–Vis, FTIR, photoluminescence and elemental analysis. Sulfanilamide was reacted with 2-bromopropionyl bromide, in the presence of pyridine, to form bromo-substituted sulfonamide key intermediates, which were subsequently treated with secondary amines to obtain novel sulfonamide derivatives. All the synthesized compounds were evaluated for in vitro antimicrobial activities and cytotoxicity. Increases in ring size, and rings bearing a nitrogen heteroatom led to improvements in antimicrobial activities. As the presence of CA IX and CA XII enzymes have been implicated in some cancerous tumors, the studies presented herein focuses on targeting these enzymes. It was found that the synthesized derivatives had in vitro anti-cancer properties, where compounds (3–6) were found to be active against all cancerous cells, and no cytotoxic effects on normal cells were observed.     

Carbonic anhydrase inhibitors: Synthesis,molecular docking,cytotoxic and inhibition of the human carbonic anhydrase isoforms I,II, IX,XII with novel benzenesulfonamides incorporating pyrrole,pyrrolopyrimidine and fused pyrrolopyrimidine moieties

A series of novel pyrroles, pyrrolopyrimidines, pyrazolopyrrolopyrimidine, triazolopyrrolopyrimidines, tetrazolopyrrolopyrimidine, triazinopyrrolopyrimidines and pyrrolopyrimidotriazepines bearing the biologically active benzenesulfonamide moiety were synthesized by using pyrrole-o-amino-carbonitrile as key intermediate. All the synthesized compounds were evaluated for their in vitro carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects against the human (h) isoforms hCA I, II, IX and XII. Among the tested derivatives, compounds 16, 18 and 20–24 showed potent activity as inhibitors for the tumor associated transmembrane isoforms (hCA IX and XII) in the nanomolar and subnanomolar range, with high selectivity. All compounds underwent cytotoxic activity assays on human breast cancer cell line (MCF-7) showing effective activity, comparable to that of the clinically used drug doxorubicin.     

Design,Synthesis, Characterization and Computational Studies of Mannich Bases Oxadiazole Derivatives as New Class of Jack Bean Urease Inhibitors

Mannich bases consisting of 1,3,4-oxadiazole-2-thione ( 3 a – 3 l ) bearing various substituents were synthesized and found potent jack bean urease inhibitors. The prepared compounds showed significantly good inhibitory activities with IC₅₀ values from 9.45±0.05 to 267.42±0.23 μM. The compound 3 k containing 4-chlorophenyl (−R) and 4-hydroxyphenyl (−R′) was most active with IC₅₀ 9.45±0.05 μM followed by 3 e (IC₅₀ 22.52±0.15 μM) in which −R was phenyl and −R′ was isopropyl group. However, when both −R and −R′ were either 4-chlorophenyl groups ( 3 l ) or only −R′ was 4-nitrophenyl ( 3 i ), both compounds were found inactive. The detailed binding affinities of the produced compounds with protein were explored through molecular docking and data-supported in-vitro enzyme inhibition profiles. Drug likeness was confirmed by in silico ADME investigations and molecular orbital analysis (HOMO-LUMO) and electrostatic potential maps were got from DFT calculations. ESP maps exposed that there are two potential binding sites with the most positive and most negative parts.     

Carboplatin derivatives with superior antitumor activity compared to the parent compound

A series of new carboplatin derivatives was synthesized by introducing fluoro, chloro, bromo and hydroxy substituents into the cyclobutane ring. The carboxylic acid groups were used for the complexation with platinum(II) fragments bearing two ammonia and (RR/SS)-trans-1,2-diaminocyclohexane ligands, respectively, as non-leaving groups. The antiproliferative activity of the new carboplatin analogues differing in the cyclobutanedicarboxylate ligands and the type of platinum fragment were studied in tests with J82 bladder cancer cells and SK-OV-3 as well as cisplatin-resistant NIH:OVCAR-3 ovarian cancer cells. The most active compounds were the 3-fluoro, 3-chloro and 3,3-difluoro derivatives of carboplatin. NMR spectroscopy showed that cis-diammine(3-chloro-1,1-cyclobutanedicarboxylato)platinum(II) was hydrolyzed much faster than carboplatin explaining its higher cytostatic activity.     

A new series of N2-substituted-5-(p-toluenesulfonylamino)phthalimide analogues as α-glucosidase inhibitors

Several members of a new family of non-sugar-type α-glycosidase inhibitors, bearing a 5-(p-toluenesulfonylamino)phthalimide moiety and various substituent at the N2 position, were synthesized and their activities were investigated. The newly synthesized compounds displayed different inhibition profile towards yeast α-glycosidase and rat intestinal α-glycosidase. Almost all the compounds had strong inhibitory activities against yeast α-glycosidase. Regarding rat intestinal α-glycosidase, only analogs with N2-aromatic substituents displayed varying degrees of inhibitory activities on rat intestinal maltase and lactase and nearly all compounds showed no inhibition against rat intestinal α-amylase. Structure–activity relationship studies indicated that 5-(p-toluenesulfonylamino)phthalimide moiety is a favorable scaffold to exert the α-glucosidase inhibitory activity and substituents at the N2 position have considerable influence on the efficacy of the inhibition activities.     

Semisynthetic teicoplanin derivatives as new influenza virus binding inhibitors: Synthesis and antiviral studies

In order to obtain new, cluster-forming antibiotic compounds, teicoplanin pseudoaglycone derivatives containing two lipophilic n-octyl chains have been synthesized. The compounds proved to be poor antibacterials, but, surprisingly, they exhibited potent anti-influenza virus activity against influenza A strains. This antiviral action was related to inhibition of the binding interaction between the virus and the host cell. Related analogs bearing methyl substituents in lieu of the octyl chains, displayed no anti-influenza virus activity. Hence, an interaction between the active, dually n-octylated compounds and the lipid bilayer of the host cell can be postulated, to explain the observed inhibition of influenza virus attachment.     

Synthesis of 1,4-bis(indolin-1-ylmethyl)benzene derivatives and their structure–activity relationships for the interaction of human carbonic anhydrase isoforms I and II

Several 1,4-bis(indolin-1-ylmethyl)benzene-based compounds containing substituents such as five, six and seven cyclic derivatives on indeno part (9a–c) were prepared and tested against two members of the pH regulatory enzyme family, carbonic anhydrase (CA). The inhibitory potencies of the compounds at the human isoforms hCA I and hCA II targets were analyzed and K_I values were calculated. K_I values of compounds for hCA I and hCA II human isozymes were measured in the range of 39.3–42.6 μM and 0.17–0.29 μM, respectively. The structurally related compound indole was also tested in order to understand the structure–activity relationship. Most of the compounds showed good CA inhibitory efficacy. In silico docking studies of these derivatives within hCA I and II were also carried out and results are supported the kinetic assays.     

Synthesis of new 3-(2-mercapto-4-oxo-4H-quinazolin-3-yl)-benzenesulfonamides with strong inhibition properties against the tumor associated carbonic anhydrases IX and XII

We report a series of novel metanilamide-based derivatives 3a–q bearing the 2-mercapto-4-oxo-4H-quinazolin-3-yl moiety as tail. All compounds were synthesized by means of straightforward condensation procedures and were investigated in vitro for their inhibition potency against the human (h) carbonic anhydrase (CA; EC 4.2.1.1.1) isoforms I, II, IX and XII. Among all compounds tested the 6-iodo 3g and the 7-fluoro 3i derivatives were the most potent inhibitors against the tumor associated CA IX and XII isoform (K_Is 1.5 and 2.7 nM respectively for the hCA IX and K_Is 0.57 and 1.9 nM respectively for the hCA XII).The kinetic data reported here strongly support compounds of this type for their future development as radiotracers in tumor pathologies which are strictly dependent on the enzymatic activity of the hCA IX and XII isoforms.     

Development of small-molecule P-gp inhibitors of the N-benzyl 1,4-dihydropyridine type: Novel aspects in SAR and bioanalytical evaluation of multidrug resistance (MDR) reversal properties

Novel series of N-benzyl 1,4-dihydropyridines have been prepared by facile syntheses. All relevant substituents of the molecular scaffold have been varied. The resulting compounds were biologically evaluated as P-glycoprotein (P-gp) inhibitors. Substitutions of the N-benzyl residue favour biological activity beside respective 3-ester functions. Most active compounds were further evaluated as multidrug resistance (MDR) modulators to restore the cytotoxic properties of varying daunorubicin applications.     

Fluorinated non-imidazole histamine H3 receptor antagonists

Fluorine substituents have become a widespread and important component in drug design and development. Here, the synthesis of fluorine containing compounds and some corresponding precursor molecules are presented for potential isotope labelling as well as their data obtained with in vitro and in vivo screenings. The compounds vary in the basic centres (piperidine or pyrrolidine) and are fluoro substituted in different positions of the basic alicyclic moiety. Pharmacological evaluation resulted in ligands with high affinities at hH₃ receptor in the nanomolar and subnanomolar concentration range and some with high antagonist in vivo potencies.     

Synthesis and Functional Characterization of Substituted Isoquinolinones as MT2-Selective Melatoninergic Ligands

A series of substituted isoquinolinones were synthesized and their binding affinities and functional activities towards human melatonin MT₁ and MT₂ receptors were evaluated. Structure-activity relationship analysis revealed that substituted isoquinolinones bearing a 3-methoxybenzyloxyl group at C5, C6 or C7 position respectively (C5>C6>C7 in terms of their potency) conferred effective binding and selectivity toward the MT₂ receptor, with 15b as the most potent compound. Most of the tested compounds were MT₂-selective agonists as revealed in receptor-mediated cAMP inhibition, intracellular Ca²⁺ mobilization and phosphorylation of extracellular signal-regulated protein kinases. Intriguingly, compounds 7e and 7f bearing a 4-methoxybenzyloxyl group or 4-methylbenzyloxyl at C6 behaved as weak MT₂-selective antagonists. These results suggest that substituted isoquinolinones represent a novel family of MT₂-selective melatonin ligands. The position of the substituted benzyloxyl group, and the substituents on the benzyl ring appeared to dictate the functional characteristics of these compounds.     

The correlation of cathodic peak potentials of vitamin K3 derivatives and their calculated electron affinities : The role of hydrogen bonding and conformational changes

2-methyl-1,4-naphtoquinone 1 (vitamin K₃, menadione) derivatives with different substituents at the 3-position were synthesized to tune their electrochemical properties. The thermodynamic midpoint potential (E_1/2) of the naphthoquinone derivatives yielding a semi radical naphthoquinone anion were measured by cyclic voltammetry in the aprotic solvent dimethoxyethane (DME). Using quantum chemical methods, a clear correlation was found between the thermodynamic midpoint potentials and the calculated electron affinities (E_A). Comparison of calculated and experimental values allowed delineation of additional factors such as the conformational dependence of quinone substituents and hydrogen bonding which can influence the electron affinities (E_A) of the quinone. This information can be used as a model to gain insight into enzyme-cofactor interactions, particularly for enzyme quinone binding modes and the electrochemical adjustment of the quinone motif.     

Structural design,synthesis and substituent effect of hydrazone-N-acylhydrazones reveal potent immunomodulatory agents

4-(Nitrophenyl)hydrazone derivatives of N-acylhydrazone were synthesized and screened for suppress lymphocyte proliferation and nitrite inhibition in macrophages. Compared to an unsubstituted N-acylhydrazone, active compounds were identified within initial series when hydroxyl, chloride and nitro substituents were employed. Structure-activity relationship was further developed by varying the position of these substituents as well as attaching structurally-related substituents. Changing substituent position revealed a more promising compound series of anti-inflammatory agents. In contrast, an N-methyl group appended to the 4-(nitrophenyl)hydrazone moiety reduced activity. Anti-inflammatory activity of compounds is achieved by modulating IL-1β secretion and prostaglandin E2 synthesis in macrophages and by inhibiting calcineurin phosphatase activity in lymphocytes. Compound SintMed65 was advanced into an acute model of peritonitis in mice, where it inhibited the neutrophil infiltration after being orally administered. In summary, we demonstrated in great details the structural requirements and the underlying mechanism for anti-inflammatory activity of a new family of hydrazone-N-acylhydrazone, which may represent a valuable medicinal chemistry direction for the anti-inflammatory drug development in general.     

Synthesis and biological evaluation of enantiomerically pure cyclopropyl analogues of combretastatin A4

To evaluate the influence of stereochemistry on biological activities of cis-cyclopropyl combretastatin A4 (CA4) analogues, we have prepared several cyclopropyl compounds in their pure enantiomeric forms. The key reactions in our synthesis are the cyclopropanation of a (Z)-alkenylboron compound bearing a chiral auxiliary, and the cross-coupling of both enantiomeric cyclopropyl trifluoroborate salts with aryl and olefinic halides. Three pairs of cis-cyclopropyl CA4 analogues were evaluated for their potential antivascular activities. The diarylcyclopropyl compounds with SR-configuration (?)-1b, (?)-2b and the cyclopropylvinyl enantiomer (+)-3a with RR-configuration were the most potent tubulin polymerization inhibitors. A correlation was noted between anti-tubulin activity and rounding up activity of endothelial cells. The cytotoxic activity on B16 melanoma cells was in the submicromolar range for most compounds, but unlike the anti-tubulin activity, there was no difference in cytotoxic activity between racemic and enantiomerically pure forms for the three series of compounds. Molecular docking studies within the colchicine binding site of tubulin were in good agreement with the tubulin polymerization inhibitory data and confirmed the importance of the configuration of the synthesized cis-cyclopropyl CA4 analogues for potential antivascular activities.