Microwave-assisted synthesis and bioevaluation of new sulfonamides.

In this study, 4-[5-(4-hydroxyphenyl)-3-aryl-4,5-dihydro-1H-pyrazol-1-yl]benzenesulfonamide derivatives (8-14) were synthesized for the first time by microwave irradiation and their chemical structures were confirmed by 1H NMR, 13C NMR and HRMS. Cytotoxic activities and inhibitory effects on carbonic anhydrase I and II isoenzymes of the compounds were investigated. The compounds 9 (PSE = 4.2), 12 (PSE = 4.1) and 13 (PSE = 3.9) with the highest potency selectivity expression (PSE) values in cytotoxicity experiments and the compounds 13 (Ki = 3.73 ± 0.91 nM toward hCA I) and 14 (Ki = 3.85 ± 0.57 nM toward hCA II) with the lowest Ki values in CA inhibition studies can be considered as leader compounds for further studies.

Investigating the antiplasmodial activity of primary sulfonamide compounds identified in open source malaria data.

In the past decade there has been a significant reduction in deaths due to malaria, in part due to the success of the gold standard antimalarial treatment - artemisinin combination therapies (ACTs). However the potential threat of ACT failure and the lack of a broadly effective malaria vaccine are driving efforts to discover new chemical entities (NCEs) to target this disease. The primary sulfonamide (PS) moiety is a component of several clinical drugs, including those for treatment of kidney disease, glaucoma and epilepsy, however this chemotype has not yet been exploited for malaria. In this study 31 PS compounds sourced from the GlaxoSmithKline (GSK) Tres Cantos antimalarial set (TCAMS) were investigated for their ability to selectively inhibit the in vitro growth of Plasmodium falciparum asexual stage malaria parasites. Of these, 14 compounds were found to have submicromolar activity (IC50 0.16-0.89 µM) and a modest selectivity index (SI) for the parasite versus human cells (SI > 12 to >43). As the PS moiety is known to inhibit carbonic anhydrase (CA) enzymes from many organisms, the PS compounds were assessed for recombinant P. falciparum CA (PfCA) mediated inhibition of CO2 hydration. The PfCA inhibition activity did not correlate with antiplasmodial potency. Furthermore, no significant difference in IC50 was observed for P. falciparum versus P. knowlesi (P > 0.05), a Plasmodium species that is not known to contain an annotated PfCA gene. Together these data suggest that the asexual intraerythrocytic stage antiplasmodial activity of the PS compounds examined in this study is likely unrelated to PfCA inhibition.

[Simultaneous determination of 10 sulfonamide antibiotics in water by solid-phase extraction and high performance liquid chromatography].

A solid-phase extraction (SPE)-high performance liquid chromatography (HPLC) method has been developed for simultaneous determination of 10 sulfonamide antibiotics in water. The analytes were first enriched and purified through a PEP solid-phase extraction column, and eluted with acetonitrile-dichloromethane solution (2: 1, V/V), then detected by a HPLC with a UV detector. The detection wavelength was 268 nm and the column temperature was 33 degrees C, using gradient elution process with acetonitrile - 0.4% acetic acid/water (V/V) as the mobile phase to achieve baseline separations of these 10 analytes. The linearity range was 10 - 2 000 microg x L(-1). The recovery ranges of standard addition for deionized water and real water samples were 73.4% - 95.6% and 70.2% - 92.5%, respectively (except for sulfonamide, were 8.5% and 8.0%). The limit of detection was 1.42-7.25 ng x L(-1). Application of this method for parts of Huangpu River in Shanghai, surface water and groundwater in Chongming Island showed that sulfonamide antibiotics were detected in different frequencies in different aqueous environments, with the concentration range of 13.3 - 241.5 ng x L(-1), proving this method is easy, rapid, sensitive and efficient to meet the needs of actual work.

European Surveillance of Antimicrobial Consumption (ESAC): outpatient use of tetracyclines, sulphonamides and trimethoprim, and other antibacterials in Europe (1997-2009).

BACKGROUND: Data on more than a decade of outpatient use of tetracyclines, sulphonamides and trimethoprim, and other antibacterials in Europe were collected from 33 countries as part of the European Surveillance of Antimicrobial Consumption (ESAC) project, funded by the European Centre for Disease Prevention and Control (ECDC). METHODS: For the period 1997-2009, data on outpatient use of systemic tetracyclines, sulphonamides and trimethoprim, and other antibacterials aggregated at the level of the active substance were collected and expressed in defined daily doses (DDD; WHO, version 2011) per 1000 inhabitants per day (DID). Using the Anatomical Therapeutic Chemical (ATC) classification, trends in the use of tetracyclines (J01A), sulphonamides and trimethoprim (J01E) and other antibacterials (J01X) over time, seasonal variation and composition of use were analysed. RESULTS: In 2009, the variations in outpatient use of systemic tetracyclines, sulphonamides and trimethoprim, and other antibacterials between countries, and also in the composition of use over time, were huge. For tetracyclines a significant and for sulphonamides and trimethoprim a non-significant decrease in use was observed between 1997 and 2009 in Europe. The seasonal variation in their use significantly decreased over time. For the other antibacterials, no significant changes in the volume of use or its seasonal variation were seen. CONCLUSIONS: As for all other major antibiotic subgroups, a striking variation in use and composition of use between countries in Europe was observed for outpatient use of tetracyclines, sulphonamides and trimethoprim, and other antibacterials. In combination with the decreasing use, especially of recommended substances, this represents an opportunity not only to reduce antibiotic use but also to improve its quality.

Assessment of cytotoxic and clastogenic effects of nimesulide: an NSAID drug in somatic cells of BALB/c mice in vivo.

The in vivo genotoxicity of nimesulide, a sulfononilide nonsteroidal anti-inflammatory drug (NSAID) with anti-inflammatory, analgesic, and antipyretic effects, was evaluated by employing a mouse in vivo chromosomal aberration test in bone marrow cells. Oral treatment of animals for 5 consecutive days with 1, 2.5, 5, and 7.5 mg/kg body weight of the drug resulted in a statistically nonsignificant reduction in mitotic index and increase in CAs/cell and percent abnormal metaphase. The results indicated that nimesulide does not induce cytotoxicity and is a weak clastogen in the bone marrow cells of the mouse in vivo. Thus, the drug presents a very weak genotoxic risk.

Factors influencing the interconversion of a new class of dibenzodiazepine sulfonamide atropisomers.

A novel family of atropisomers based on a conformationally constrained seven membered ring system is investigated using a combination of preparative chiral chromatography, circular dichroism, and other analytical techniques. The influence of structure on the rate of atropisomer interconversion was explored with a series of analogs showing a range of interconversion rates ranging from very fast (undetectable on the HPLC timescale) to very slow (half life of many days).

A novel, species-specific class of uncompetitive inhibitors of gamma-glutamyl transpeptidase.

Expression of gamma-glutamyl transpeptidase (GGT) in tumors contributes to resistance to radiation and chemotherapy. GGT is inhibited by glutamine analogues that compete with the substrate for the gamma-glutamyl binding site. However, the glutamine analogues that have been evaluated in clinical trials are too toxic for use in humans. We have used high throughput screening to evaluate small molecules for their ability to inhibit GGT and have identified a novel class of inhibitors that are not glutamine analogues. These compounds are uncompetitive inhibitors, binding the gamma-glutamyl enzyme complex. OU749, the lead compound, has an intrinsic K(i) of 17.6 microm. It is a competitive inhibitor of the acceptor glycyl-glycine, which indicates that OU749 occupies the acceptor site while binding to the gamma-glutamyl substrate complex. OU749 is more than 150-fold less toxic than the GGT inhibitor acivicin toward dividing cells. Inhibition of GGT by OU749 is species-specific, inhibiting GGT isolated from human kidney with 7-10-fold greater potency than GGT isolated from rat or mouse kidney. OU749 does not inhibit GGT from pig cells. Human GGT expressed in mouse fibroblasts is inhibited by OU749 similarly to GGT from human cells, which indicates that the species specificity is determined by differences in the primary structure of the protein rather than species-specific, post-translational modifications. These studies have identified a novel class of inhibitors of GGT, providing the basis for further development of a new group of therapeutics that inhibit GGT by a mechanism distinct from the toxic glutamine analogues.

Non peptidic urotensin II antagonists: perspectives for a new class of drugs.

Urotensin II (U-II) is a cyclic peptide isolated from a fish. Subsequently, human U-II and its receptor were identified. In rat thoracic aorta U-II triggers powerful vasoconstrictor activity. However, the constrictor response to U-II appears to be variable and highly dependent on the vascular bed examined. Vasoconstriction is not its only effect; U-II and its receptor have been demonstrated in the central nervous system, where U-II induces a cardiovascular, behavioural, motor and endocrine response and in the kidney, where it seems to influence renal hemodynamics but also salt and water excretion, in rat pancreas where it inhibits insulin secretion, in the heart where it seems to play a role in cardiac hypertrophy and fibrosis. In humans high plasma or urine levels of U-II have been described in some pathologic conditions. Peptidic and non peptidic UT receptor antagonists have been synthesized and their effects have been evaluated particularly in animal models of diabetes and heart failure. After promising results in animal models, palosuran, a non peptidic U-II antagonist has been administered also in diabetic patients to evaluate its potential nephroprotective activity. This review presents the data available on the U-II system and its role in physiological and pathological conditions, together with data regarding palosuran and other non peptidic and peptidic U-II antagonists.

Thermodynamic benchmark study using Biacore technology.

A total of 22 individuals participated in this benchmark study to characterize the thermodynamics of small-molecule inhibitor-enzyme interactions using Biacore instruments. Participants were provided with reagents (the enzyme carbonic anhydrase II, which was immobilized onto the sensor surface, and four sulfonamide-based inhibitors) and were instructed to collect response data from 6 to 36 degrees C. van't Hoff enthalpies and entropies were calculated from the temperature dependence of the binding constants. The equilibrium dissociation and thermodynamic constants determined from the Biacore analysis matched the values determined using isothermal titration calorimetry. These results demonstrate that immobilization of the enzyme onto the sensor surface did not alter the thermodynamics of these interactions. This benchmark study also provides insights into the opportunities and challenges in carrying out thermodynamic studies using optical biosensors.

Classification of torasemide based on the Biopharmaceutics Classification System and evaluation of the FDA biowaiver provision for generic products of CLASS I drugs.

The biopharmaceutical properties of an in-house developed new crystal modification of torasemide (Torasemide N) were investigated in comparison with the most well known crystal modification form of torasemide (Torasemide I) in order to classify the drug according to the Biopharmaceutics Classification System (BCS), and to evaluate the data in line with current US Food and Drug Administration (FDA) guidance (with biowaiver provision for Class I drugs) to determine if the biowaiver provision could be improved. The solubility profiles of Torasemide I and Torasemide N were determined, and tablets prepared from both forms of the drug were studied for in-vitro release characteristics in media recommended by the current FDA guidance for biowaiver of generic products, and in other media considered more appropriate for the purpose than the ones recommended by the FDA. Two separate bioequivalence studies in healthy humans (following oral administration) were performed with two test products (both prepared from Torasemide I) against a single reference product (prepared from Torasemide N). The absorption profiles of the drug from the tablets were determined by deconvolution for comparison with the in-vitro release profiles to determine the appropriateness of some dissolution media for predicting in-vivo performance and to determine the comparative rate and extent of absorption. The drug was absorbed from the tested products quickly and almost completely (about 95% within 3.5 h of administration). However, one test product failed to meet the bioequivalence criteria and had a significant initial lower absorption rate profile compared with the reference product (P< or =0.05), whereas the other product was bioequivalent and had a similar absorption profile to the reference product. A dissolution medium at pH 5.0, in which torasemide has minimum solubility, was found to be more discriminatory than the media recommended by the FDA. Torasemide has been classified as a Class I drug according to the BCS up to a maximum dose of 40 mg and the data suggest that the current FDA guidance could be improved by giving more emphasis to selection of appropriate dissolution media than is given in its current form for approving biowaiver to generic products of Class I drugs.

Comparative analysis of 10 small molecules binding to carbonic anhydrase II by different investigators using Biacore technology.

In this benchmark study, 26 investigators were asked to characterize the kinetics and affinities of 10 sulfonamide inhibitors binding to the enzyme carbonic anhydrase II using Biacore optical biosensors. A majority of the participants collected data that could be fit to a 1:1 interaction model, but a subset of the data sets obtained from some instruments were of poor quality. The experimental errors in the k(a), k(d), and K(D) parameters determined for each of the compounds averaged 34, 24, and 37%, respectively. As expected, the greatest variation in the reported constants was observed for compounds with exceptionally weak affinity and/or fast association rates. The binding constants determined using the biosensor correlated well with solution-based titration calorimetry measurements. The results of this study provide insight into the challenges, as well as the level of experimental variation, that one would expect to observe when using Biacore technology for small molecule analyses.

Profile of past and current clinical trials involving endothelin receptor antagonists: the novel "-sentan" class of drug.

Since its initial characterization in 1988, over 18,236 papers, including 2,485 reviews, have been published in the endothelin (ET) field. Over this period, several generations of selective and mixed (dual) ET receptor antagonists (ERAs), from peptidic backbones to orally active potent (subnanomolar) small molecular compounds, have been developed. These agents have been studied in many experimental animal models of various pathological conditions (cardiovascular, respiratory, and neuro-immunological). Continued basic research has led to a better understanding of the complex interactions between the ET axis and other biologic systems in human pathophysiology. The first clinical trial involved patients with idiopathic pulmonary arterial hypertension and led to approval of bosentan (Tracleer) for use in the United States and Europe in 2002. Since then, bosentan, the only currently approved dual (mixed) ERA, has been used in numerous other clinical trials. In addition, more selective ET(A) receptor antagonists (ambrisentan, atrasentan, avosentan, clazosentan, darusentan, and sitaxsentan) are undergoing clinical trials. Here we outline the ERAs undergoing development and summarize the standing of completed and ongoing trials at the time of the Ninth International Conference on Endothelin and even thereafter. This review is intended to provide a useful reference for those interested in the current state of clinical trials involving ERAs, and to identify lessons that might apply to the design of future trials.

Carbonic anhydrase inhibitors: inhibition of the human transmembrane isozyme XIV with a library of aromatic/heterocyclic sulfonamides.

The first inhibition study of the transmembrane carbonic anhydrase (CA, EC 4.2.1.1) isozymes hCA XIV with a library of aromatic and heteroaromatic sulfonamides synthesized earlier is reported. Most of the inhibitors were sulfanilamide, homosulfanilamide and 4-aminoethyl-benzenesulfonamide derivatives, to which tails that would induce diverse physicochemical properties have been attached at the amino moiety. Several of these compounds were metanilamide, benzene-1,3-disulfonamide or the 1,3,4-thiadiazole/thiadiazoline-2-sulfonamide derivatives. The tails incorporated in these molecules were of the alkyl/aryl-carboxamido/ sulfonamido-, ureido- or thioureido-types. The sulfanilamides acylated at the 4-amino group with short aliphatic/aromatic moieties incorporating 2-6 carbon atoms showed modest hCA XIV inhibitory activity (K(I)-s in the range of 1.25-4.2 microM) which were anyhow better than that of sulfanilamide (K(I) of 5.4 microM). Better activity showed the homosulfanilamide and 4-aminoethyl-benzenesulfonamide derivatives bearing arylsulfonamido/ureido and thioureido moieties, with K(I)'s in the range of 203-935 nM. The best activity was observed for the heteroaromatic compounds incorporating 1,3,4-thiadiazole/thiadiazoline-2-sulfonamide and 5-arylcarboxamido/sulfonamido moieties, with K(I)'s in the range of 10-85 nM. All these compounds were generally also much better inhibitors of the other two transmembrane CA isozyme, hCA IX and XII. Thus, highly potent hCA XIV inhibitors were detected, but isozyme-specific inhibitors were not discovered for the moment.

Design, synthesis, and biological evaluation of N-acetyl-2-carboxybenzenesulfonamides: a novel class of cyclooxygenase-2 (COX-2) inhibitors.

N-Acetyl-2-carboxybenzenesulfonamide (11), and a group of analogues possessing an appropriately substituted-phenyl substituent (4-F, 2,4-F(2), 4-SO(2)Me, 4-OCHMe(2)) attached to its C-4, or C-5 position, were synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1/COX-2 inhibition studies showed that 11 is a more potent inhibitor (COX-1 IC(50)=0.06microM; COX-2 IC(50)=0.25microM) than aspirin (COX-1 IC(50)=0.35microM; COX-2 IC(50)=2.4microM), and like aspirin [COX-2 selectivity index (S.I.)=0.14], 11 is a nonselective COX-2 inhibitor (COX-2 S.I.=0.23). Regioisomers having a 2,4-difluorophenyl substituent attached to the C-4 (COX-2 IC(50)=0.087microM; COX-2 S.I. >1149), or C-5 (COX-2 IC(50)=0.77microM, SI>130), position of 11 exhibited the most potent and selective COX-2 inhibitory activity relative to the reference drug celecoxib (COX-1 IC(50)=33.1microM; COX-2 IC(50)=0.07microM; COX-2 S.I.=472). N-Acetyl-2-carboxybenzenesulfonamide (11, ED(50)=49 mg/kg), and its C-4 2,4-difluorophenyl derivative (ED(50)=91 mg/kg), exhibited superior antiinflammatory activity (oral dosing) in a carrageenan-induced rat paw edema assay compared to aspirin (ED(50)=129 mg/kg). These latter compounds exhibited comparable analgesic activity to the reference drug diflunisal, and superior analgesic activity compared to aspirin, in a 4% NaCl-induced abdominal constriction assay. A molecular modeling (docking) study indicated that the SO(2)NHCOCH(3) substituent present in N-acetyl-2-carboxy-4-(2,4-fluorophenyl)benzenesulfonamide, like the acetoxy substituent in aspirin, is suitably positioned to acetylate the Ser(530) hydroxyl group in the COX-2 primary binding site. The results of this study indicate that the SO(2)NHCOCH(3) pharmacophore present in N-acetyl-2-carboxybenzenesulfonamides is a suitable bioisostere for the acetoxy (OCOMe) group in aspirin.

Simultaneous determination of 16 sulfonamides in honey by liquid chromatography/tandem mass spectrometry.

A method is described for the determination of 16 sulfonamides in honey. Samples are dissolved in phosphoric acid solution (pH2), cleaned up with 2 solid-phase extraction (SPE) cartridges, an aromatic sulfonic cation-exchange cartridge and an Oasis HLB SPE cartridge, and analyzed both qualitatively and quantitatively by liquid chromatography/tandem mass spectrometry (LC/MS/MS) under the selected conditions. Without exception, calibration curves were linear (r = > 0.995), when sulfamethizole was between 1.0 and 25.0 microg/kg; sulfacetamide, sulfapyridine, sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfamerazine, sulfisoxazole, sulfamonomethoxine, and sulfadoxine were between 2.0 and 50.0 microg/kg; sulfamethoxypyridazine, sulfadimethoxine, and sulfathiazole were between 4.0 and 100.0 microg/kg; sulfamethazine and sulfameter were between 8.0 and 200.0 microg/kg; and sulfaphenazole was between 12.0 and 300.0 microg/kg. Average recoveries at 4 fortification levels in the range of 1.0-300 microg/kg in honey were 70.9-102.5%, and relative standard deviations were 2.02-11.52%. The limits of quantitation for the 16 sulfonamides were between 1.0 and 12.0 microg/kg, with the LC/MS/MS method.

Mass spectrometric studies of some novel sulfonamides.

A recent paper described the overall 5-endo cyclisation of homoallylic sulfonamides to give pyrrolidines. This reaction was also used to prepare polycyclic systems. Mass spectrometric analysis using classical electron ionisation spectra and accurate mass measurement played a vital role in confirming the proposed structures for the products. These materials were not amenable to newer mass spectrometric methods and this study shows the continuing importance of older techniques.