Synthesis and cytotoxic activities of novel copper and silver complexes of 1,3-diaryltriazene-substituted sulfonamides.

In this study, a series of 10 novel copper (II) and silver complexes of 1,3-diaryltriazene-substituted sulfonamides was synthesised. All the synthesised ligands and their metal complexes were assessed for in vitro cytotoxicity against human colorectal adenocarcinoma (DLD-1), cervix carcinoma (HeLa), breast adenocarcinoma (MDA-MB-231), colon adenocarcinoma (HT-29), endometrial adenocarcinoma (ECC-1), prostate cancer (DU-145 and PC-3), normal embryonic kidney (HEK-293), normal prostate epithelium (PNT-1A), and normal retinal pigment epithelium (ARPE-19) cells. Most of the metal complexes from the series showed to be more active against all cancerous cells than the uncomplexed 1,3-diaryltriazene-substituted sulfonamides, and lower cytotoxic effects observed on normal cells. Most of the Cu (II) and Ag (I) metal complexes from the presented series showed high cytotoxic activity against HeLa cells with IC50 values ranging from 2.08 to >300 µM. Specifically, compound L3-Ag showed one of the highest cytotoxicity against all cancer cell lines with IC50 values between 3.30 to 16.18 µM among other tested compounds.

Novel thiazolidinone-containing compounds, without the well-known sulphonamide zinc-binding group acting as human carbonic anhydrase IX inhibitors.

A small collection of 26 structurally novel thiazolidinone-containing compounds, without the well-known sulphonamide zinc-binding group, were synthesised and tested in enzyme inhibition assays against the tumour-associated hCA IX enzyme. Inhibition constants in the lower micromolar region (KI < 25 µM) have been measured for 17 of the 26 compounds. Even though the KI values are relatively weak, the fact that they do not contain a sulphonamide moiety suggests that these compounds do not interact with the active site zinc ion. Therefore, docking studies and molecular dynamics simulations have been performed to suggest binding poses for these structurally novel inhibitors.

Target-based drug discovery through inversion of quantitative structure-drug-property relationships and molecular simulation: CA IX-sulphonamide complexes.

In this work, a target-based drug screening method is proposed exploiting the synergy effect of ligand-based and structure-based computer-assisted drug design. The new method provides great flexibility in drug design and drug candidates with considerably lower risk in an efficient manner. As a model system, 45 sulphonamides (33 training, 12 testing ligands) in complex with carbonic anhydrase IX were used for development of quantitative structure-activity-lipophilicity (property)-relationships (QSPRs). For each ligand, nearly 5,000 molecular descriptors were calculated, while lipophilicity (logkw) and inhibitory activity (logKi) were used as drug properties. Genetic algorithm-partial least squares (GA-PLS) provided a QSPR model with high prediction capability employing only seven molecular descriptors. As a proof-of-concept, optimal drug structure was obtained by inverting the model with respect to reference drug properties. 3509 ligands were ranked accordingly. Top 10 ligands were further validated through molecular docking. Large-scale MD simulations were performed to test the stability of structures of selected ligands obtained through docking complemented with biophysical experiments.

Rapid labelling and covalent inhibition of intracellular native proteins using ligand-directed N-acyl-N-alkyl sulfonamide.

Selective modification of native proteins in live cells is one of the central challenges in recent chemical biology. As a unique bioorthogonal approach, ligand-directed chemistry recently emerged, but the slow kinetics limits its scope. Here we successfully overcome this obstacle using N-acyl-N-alkyl sulfonamide as a reactive group. Quantitative kinetic analyses reveal that ligand-directed N-acyl-N-alkyl sulfonamide chemistry allows for rapid modification of a lysine residue proximal to the ligand binding site of a target protein, with a rate constant of ~104 M-1 s-1, comparable to the fastest bioorthogonal chemistry. Despite some off-target reactions, this method can selectively label both intracellular and membrane-bound endogenous proteins. Moreover, the unique reactivity of N-acyl-N-alkyl sulfonamide enables the rational design of a lysine-targeted covalent inhibitor that shows durable suppression of the activity of Hsp90 in cancer cells. This work provides possibilities to extend the covalent inhibition approach that is currently being reassessed in drug discovery.

Optimization and Comparison of Synthetic Procedures for a Group of Triazinyl-Substituted Benzene-Sulfonamide Conjugates with Amino Acids.

Sulfonamides incorporating 1,3,5-triazine moieties can selectively and potently inhibit carbonic anhydrase transmembrane isoforms IX, XII, and XIV over cytosolic isoforms I and II. In the present work, a highly effective synthetic procedure was proposed for this group of potent cancerostatic drugs and compared with previously used methods. The synthesis of triazinyl-substituted benzene-sulfonamide conjugates with amino acids can be easily carried out using sodium carbonate-based water solution as a synthetic medium instead of N,N-Diisopropylethylamine/Dimethylformamide. The benefits of this synthetic procedure include: (i) high selectivity of the creation of disubstituted conjugates; (ii) several times higher yield (≥95%) than that achieved previously; (iii) elimination of organic solvents by the use of an environmental friendly water medium (green chemistry); (iv) simple and fast isolation of the product. The synthesis and resulting products were evaluated using TLC, IR, NMR, and MS methods. The present work demonstrates a significant advantage in providing shortened routes to target structures.

Design and Comparative Evaluation of the Anticonvulsant Profile, Carbonic-Anhydrate Inhibition and Teratogenicity of Novel Carbamate Derivatives of Branched Aliphatic Carboxylic Acids with 4-Aminobenzensulfonamide.

Epilepsy is one of the most common neurological diseases, with between 34 and 76 per 100,000 people developing epilepsy annually. Epilepsy therapy for the past 100+ years is based on the use of antiepileptic drugs (AEDs). Despite the availability of more than twenty old and new AEDs, approximately 30% of patients with epilepsy are not seizure-free with the existing medications. In addition, the clinical use of the existing AEDs is restricted by their side-effects, including the teratogenicity associated with valproic acid that restricts its use in women of child-bearing age. Thus, there is an unmet clinical need to develop new, effective AEDs. In the present study, a novel class of carbamates incorporating phenethyl or branched aliphatic chains with 6-9 carbons in their side-chain, and 4-benzenesulfonamide-carbamate moieties were synthesized and evaluated for their anticonvulsant activity, teratogenicity and carbonic anhydrase (CA) inhibition. Three of the ten newly synthesized carbamates showed anticonvulsant activity in the maximal-electroshock (MES) and 6 Hz tests in rodents. In mice, 3-methyl-2-propylpentyl(4-sulfamoylphenyl)carbamate(1), 3-methyl-pentan-2-yl-(4-sulfamoylphenyl)carbamate (9) and 3-methylpentyl, (4-sulfamoylphenyl)carbamate (10) had ED50 values of 136, 31 and 14 mg/kg (MES) and 74, 53, and 80 mg/kg (6 Hz), respectively. Compound (10) had rat-MES-ED50 = 13 mg/kg and ED50 of 59 mg/kg at the mouse-corneal-kindling test. These potent carbamates (1,9,10) induced neural tube defects only at doses markedly exceeding their anticonvuslnat-ED50 values. None of these compounds were potent inhibitors of CA IV, but inhibited CA isoforms I, II and VII. The anticonvulsant properties of these compounds and particularly compound 10 make them potential candidates for further evaluation and development as new AEDs.

Photodegradation of Oryzalin in aqueous isopropanol and acetonitrile.

The phototransformation of Oryzalin was studied under UV light (λmax ≥ 290 nm) and sunlight (λmax ≥ 250 nm) in aqueous isopropanol and acetonitrile solution in absence and presence of TiO2 as sensitizer. The rate of photodegradation of Oryzalin in different solvent system followed first-order kinetics, and calculated half-lives were found to be in the range of 23.52-53.75 h for UV light and 41.23-61.43 h for sunlight. From this study, total 12 photoproducts were identified and characterized on the basis of column chromatography and Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved was hydrolysis, breaking of sulfonic bond, and loss of amino and sulfonic acid group.

Dye adsorption of cotton fabric grafted with PPI dendrimers: Isotherm and kinetic studies.

In this research, the cotton fabrics grafted with two generations of the poly(propylene imine) dendrimers were applied to adsorb textile dyes from aqueous solutions. Direct Red 80 (anionic dye), Disperse Yellow 42 (nonionic dye) and Basic Blue 9 (cationic dye) were selected as model dyes. The effect of various experimental parameters such as initial concentration of dyes, charge of dyes molecule, salt and pH was investigated on the adsorption process. Furthermore, kinetics and equilibrium of the adsorption process on the grafted samples were studied. It was found that maximum adsorption of anionic and disperse dyes took place at around pH 3, while cationic dye could be adsorbed at around pH 11. The Langmuir equation was able to describe the mechanism of dyes adsorption. In addition, the second-order equation was found to be fit with the kinetics data. Interestingly, it seems that the dye adsorption of the grafted fabrics is strongly pH dependent.

Isatin sulfonamides: potent caspases-3 and -7 inhibitors, and promising PET and SPECT radiotracers for apoptosis imaging.

Caspases-3 and -7 play an essential role in apoptosis. Isatin sulfonamides have been identified as potent inhibitors of these executing caspases. Besides pharmacological application, these compounds can also serve as recognition units to target caspases using positron emission tomography (PET) and single-photon emission computed tomography (SPECT) when labeled with a positron or a gamma emitter. Fluorinated, alkylated, arylated isatin derivatives, in addition to derivatives modified with heterocycles, have been prepared in order to improve their binding potency, selectivity and metabolic stability. Structural optimization has led to stable, highly active inhibitors, which after labeling have been applied in PET studies in tumor mouse models and for first preclinical and clinical investigations with healthy human volunteers. The results support further development of such radiotracers for clinical apoptosis imaging.

Inhibition studies of new ureido-substituted sulfonamides incorporating a GABA moiety against human carbonic anhydrase isoforms I-XIV.

Reaction of γ-Boc-GABA, prepared by protecting the γ-amino moiety of the amino butyric acid with the tert-butyloxycarbonyl (Boc) protecting group, with 4-methyl/ethyl benzenesulfonamide, followed by removal of the Boc protecting group in 3 M HCl afforded the corresponding hydrochlorides, which were further derivatized by reaction with a varying of aryl isocyanates to give a new classes of ureido substituted benzenesulfonamide containing a GABA moiety. Inhibition studies of the human carbonic anhydrase(CA, EC 4.2.1.1) isoforms, CA I­XIV with these new compounds revealed that they possess moderate-weak inhibition potency against hCA III, IV, VA, VI and XIII, rather efficient inhibitory power against hCA I, VI, and IX, and excellent inhibition of the physiologically relevant hCA II and VII, as well as of the two tumor-associated isoforms CA IX and XII. The inhibition profile of the new ureido-substituted benzenesulfonamides reported here is thus very different from the corresponding ureido-substituted analogs incorporating sulfanilamide, which were previously investigated as inhibitors of some of these enzymes.

The structure of a tetrameric α-carbonic anhydrase from Thermovibrio ammonificans reveals a core formed around intermolecular disulfides that contribute to its thermostability.

Carbonic anhydrase enzymes catalyse the reversible hydration of carbon dioxide to bicarbonate. A thermophilic Thermovibrio ammonificans α-carbonic anhydrase (TaCA) has been expressed in Escherichia coli and structurally and biochemically characterized. The crystal structure of TaCA has been determined in its native form and in two complexes with bound inhibitors. The tetrameric enzyme is stabilized by a unique core in the centre of the molecule formed by two intersubunit disulfides and a single lysine residue from each monomer that is involved in intersubunit ionic interactions. The structure of this core protects the intersubunit disulfides from reduction, whereas the conserved intrasubunit disulfides are not formed in the reducing environment of the E. coli host cytosol. When oxidized to mimic the environment of the periplasmic space, TaCA has increased thermostability, retaining 90% activity after incubation at 70°C for 1 h, making it a good candidate for industrial carbon-dioxide capture. The reduction of all TaCA cysteines resulted in dissociation of the tetrameric molecule into monomers with lower activity and reduced thermostability. Unlike other characterized α-carbonic anhydrases, TaCA does not display esterase activity towards p-nitrophenyl acetate, which appears to result from the increased rigidity of its protein scaffold.

Evaluation of potential cationic probes for the detection of proline and betaine.

Osmoregulants are the substances that help plants to tolerate environmental extremes such as salinity and drought. Proline and betaine are two of the most commonly studied osmoregulants. An indirect UV CE method has been developed for simultaneous determination of these osmoregulants. A variety of reported probes and compounds were examined as potential probes for the indirect detection of proline and betaine. Mobility and UV-absorption properties highlighted sulfanilamide as a potential probe for indirect analysis of proline and betaine. Using 5 mM sulfanilamide at pH 2.2 with UV detection at 254 nm, proline and betaine were separated in less than 15 min. The LODs for proline and betaine were 11.6 and 28.3 µM, respectively. The developed method was successfully applied to quantification of these two osmoregulants in spinach and beetroot samples.

Design, synthesis and biological evaluation of sulfamide and triazole benzodiazepines as novel p53-MDM2 inhibitors.

A series of sulfamide and triazole benzodiazepines were obtained with the principle of bioisosterism. The p53-murine double minute 2 (MDM2) inhibitory activity and in vitro antitumor activity were evaluated. Most of the novel benzodiazepines exhibited moderate protein binding inhibitory activity. Particularly, triazole benzodiazepines showed good inhibitory activity and antitumor potency. Compound 16 had promising antitumor activity against the U-2 OS human osteosarcoma cell line with an IC50 value of 4.17 µM, which was much better than that of nutlin-3. The molecular docking model also successfully predicted that this class of compounds mimicked the three critical residues of p53 binding to MDM2.

Synthesis and carbonic anhydrase I, II, IX and XII inhibition studies of 4-N,N-disubstituted sulfanilamides incorporating 4,4,4-trifluoro-3-oxo-but-1-enyl, phenacylthiourea and imidazol-2(3H)-one/thione moieties.

A series of sulfonamides incorporating the sulfanilamide (SA) scaffold were prepared. Reaction of the 4-amino moiety of SA with benzyl chlorides or substituted bromoacetophenones afforded the 4-mono-alkylated derivatives which were then reacted with 1,1,1-trifluoro-4-isobutoxybut-3-en-2-one leading to a series of 4-N,N-disubstituted SAs. The key intermediates were also reacted with ethoxycarbonyl isothiocyanate leading to thioureas or were cyclized in the presence of potassium cyanate/isothiocyanate to the corresponding imidazol-2(3H)-one/thiones. The new compounds were tested as inhibitors of four carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic CA I and II, and the transmembrane, tumor-associated CA IX and XII. These sulfonamides were ineffective CA I and II inhibitors but were nanomolar CA IX and XII inhibitors, making them of interest as clinical candidates for antitumor/antimetastasis applications.

Anti-neoplastic activity of 1,3-diaza-2-functionalized-adamantan-6-one compounds against melanoma cells.

Four series of 1,3-diaza-2-functionalized-adamantan-6-one derivatives, bearing at the 2 position SO, SO2, POCl and PO2H functional groups, were synthesized via a key quadruple Mannich reaction, followed by transformation of an aminal functionality into the final 2-thia- and 2-phospha compounds. The compounds were tested for cytotoxic activity against the mouse B16-F10 melanoma cell line. Malignant melanoma is notorious for its high resistance to chemotherapy, and new anti-melanoma drugs are urgently needed. The 2-thia compounds exhibited poor proliferation inhibition activity, but the 2-phospha derivatives showed significant activity, with IC50 values of 10-60 µM. The compounds induced cell death by G2/M cell cycle arrest, which led to apoptosis, as determined by Annexin V-FITC/PI staining, mitochondrial membrane potential changes assessed by the JC-1 reagent, caspases 3 and 7 activation, and morphological changes.

Teratology study of amide derivatives of branched aliphatic carboxylic acids with 4-aminobenzensulfonamide in NMRI mice.

BACKGROUND: Valproic acid (VPA), widely used to treat epilepsy, bipolar disorders, and migraine prophylaxis, is known to cause neural tube and skeletal defects in humans and animals. Aminobenzensulfonamide derivatives of VPA with branched aliphatic carboxylic acids, namely 2-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (MSP), 2-ethyl-N-(4-sulfamoyl-phenyl)-butyramide (ESB), 2-ethyl-4-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (EMSP), and 2-ethyl-N-(4-sulfamoyl-benzyl)-butyramide (ESBB), have shown more potent anticonvulsant activity than VPA in preclinical testing. Here, we investigated the teratogenic effects of these analogous compounds of VPA in NMRI mice. METHODS: Pregnant NMRI mice were given a single subcutaneous injection of either VPA at 1.8 or 3.6 mmol/kg, or MSP, ESB, EMSP, or ESBB at 1.8, 3.6, or 4.8 mmol/kg on gestation day (GD) 8. Cesarean section was performed on GD 18, and the live fetuses were examined for external and skeletal malformations. RESULTS: Compared with VPA, which induced neural tube defects (NTDs) in fetuses at 1.8 and 3.6 mmol/kg, the analog derivatives induced no NTDs at dose levels up to 4.8 mmol/kg (except for a single case of exencephaly at 4.8 mmol/kg MSP). Skeletal examination showed several abnormalities mainly at the axial skeletal level with VPA at 1.8 mmol/kg. Fused vertebrae and/or fused ribs were also observed with MSP, ESB, EMSP, and ESBB, they were less severe and seen at a lower incidence that those induced by VPA at the same dose level. CONCLUSIONS: In addition to exerting more potent preclinical antiepileptic activity, teratology comparison indicates that aminobenzensulfonamide analogs are generally more weakly teratogenic than VPA.

Expanding the synthesis of new trans-sulfonamide platinum complexes: cytotoxicity, SAR, fluorescent cell assays and stability studies.

In this manuscript, we describe the synthesis of new trans-N-sulfonamide platinum complexes and their antiproliferative activity (GI50, µM) in human solid tumors cells. The structure activity relationships (SAR), with different new synthesized complexes by variation in ligand, halogen and also in the stereochemistry of the ligand, has been studied. Solubility and stability studies have also been carried out as well as fluorescent cell assays in order to clarify the final target in the tumor cells.

Lipid nanoparticles containing oryzalin for the treatment of leishmaniasis.

Oryzalin is a dinitroaniline drug that has attracted recent interest for the treatment of leishmaniasis. Its use as an antiparasitic therapeutic agent is limited by the low water solubility associated with an in vivo rapid clearance, leading to the administration of larger and possibly toxic doses in in vivo studies, and the use of solvents that may lead to undesirable side effects. In the present work oryzalin-containing lipid nanoparticles were produced by a emulsion-solvent evaporation technique using a composition suitable for parenteral administration, i.e., tripalmitin (solid lipid) and a complex mixture of three emulsifying agents (soya lecithin, Tween® 20 and sodium deoxycholate). Physicochemical characterization included the determination of mean particle size, polydispersity index, zeta potential, encapsulation efficiency and DSC studies. Final formulations revealed values of <140 nm (PI<0.2) and zeta potential of ≈-35 mV, as well as encapsulation efficiency >75%. The effects of various processing parameters, such as lipid and surfactant and composition and concentration, as well as the stability during the harsh procedures of autoclaving (121°C/15 min) and freeze-drying were also evaluated. Formulations revealed to be stable throughout freeze-drying and moist-heath sterilization without significant variations on physicochemical properties and no significant oryzalin losses. The use of a complex surfactant mixture proved crucial for preserving formulation stability. Particularly, lecithin appears as a key component in the stabilization of tripalmitin-based oryzalin-containing lipid nanoparticles. Finally, cell viability studies demonstrated that the incorporation of oryzalin in nanoparticles decreases cytotoxicity, thus suggesting this strategy may improve tolerability and therapeutic index of dinitroanilines.

A new cadmium reduction device for the microplate determination of nitrate in water, soil, plant tissue, and physiological fluids.

A reusable catalytic reductor consisting of 96 copperized-cadmium pins attached to a microplate lid was developed to simultaneously reduce nitrate (NO3-) to nitrite (NO2-) in all wells of a standard microplate. The resulting NO2- is analyzed colorimetrically by the Griess reaction using a microplate reader. Nitrate data from groundwater samples analyzed using the new device correlated well with data obtained by ion chromatography (r2 = 0.9959). Soil and plant tissue samples previously analyzed for NO3- in an interlaboratory validation study sponsored by the Soil Science Society of America were also analyzed using the new technique. For the soil sample set, the data are shown to correlate well with the other methods used (r2 = 0.9976). Plant data correlated less well, especially for samples containing low concentrations of NO3-. Reasons for these discrepancies are discussed, and new techniques to increase the accuracy of the analysis are explored. In addition, a method is presented for analyzing NO3- in physiological fluids (blood serum and urine) after matrix modification with Somogyi's reagent. A protocol for statistical validation of data when analyzing samples with complex matrixes is also established. The simplicity, adaptability, and low cost of the device indicate its potential for widespread application.

Metabolic and chemical origins of cross-reactive immunological reactions to arylamine benzenesulfonamides: T-cell responses to hydroxylamine and nitroso derivatives.

Exposure to sulfamethoxazole (SMX) is associated with T-cell-mediated hypersensitivity reactions in human patients. T-cells can be stimulated by the putative metabolite nitroso SMX, which binds irreversibly to protein. The hydroxylamine and nitroso derivatives of three arylamine benzenesulfonamides, namely, sulfamethozaxole, sulfadiazine, and sulfapyridine, were synthesized, and their T-cell stimulatory capacity in the mouse was explored. Nitroso derivatives were synthesized by a three-step procedure involving the formation of nitro and hydroxylamine sulfonamide intermediates. For immune activation, female Balb-c strain mice were administered nitroso sulfonamides four times weekly for 2 weeks. After 14 days, isolated splenocytes were incubated with the parent compounds, hydroxylamine metabolites, and nitroso derivatives to measure antigen-specific proliferation. To explore the requirement of irreversible protein binding for spleen cell activation, splenocytes were incubated with nitroso derivatives in the presence or absence of glutathione. Splenocytes from nitroso sulfonamide-sensitized mice proliferated and secreted interleukin (IL)-2, IL-4, IL-5, and granulocyte monocyte colony-stimulating factor following stimulation with nitroso derivatives but not the parent compounds. Splenocytes from sensitized mice were also stimulated to proliferate with hydroxylamine and nitroso derivatives of the structurally related sulfonamides. The addition of glutathione inhibited the nitroso-specific T-cell response. Hydroxylamine metabolites were unstable in aqueous solution: Spontaneous transformation yielded appreciable amounts of nitroso and azoxy compounds as well as the parent compounds within 0.1 h. T-cell cross-reactivity with nitroso sulfonamides provides a mechanistic explanation as to why structurally related arylamine benzenesulfonamides are contraindicated in hypersensitive patients.