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At least 127 records · Page 7Linked to original sources
PubMed1998

Determination of sulfonamide antibiotics by gas chromatography coupled with atomic emission detection.

The paper describes the analysis of nine sulfonamides, chosen as the most widely used representatives of an important class of antibacterial drugs. Atomic emission detection has been found to allow simultaneous quantification and identification of the N1-methylated derivatives, which are resolved efficiently by conventional capillary gas chromatography. Results are given concerning the linearity of the response and the characterization of the individual compounds by the elemental ratio of their carbon, nitrogen and sulfur content. The method looks promising for the quantitative analysis and confirmation of sulfonamide residues in complex mixtures.

Anti-Infective Agents↗
PubMed2004

Chemometric and derivative methods as flexible spectrophotometric approaches for dissolution and assaying tests in multicomponent tablets.

Two derivative spectrophotometric (ratio derivative spectra and algorithm bivariate calibration) and a chemometric methods (partial least squares, PLS) are proposed for the simultaneous determination of binary mixtures in tablet analysis and dissolutions tests, without prior separation. These approaches are successfully applied to quantify trimethoprim (TMP) combined with sulfamethoxazole (SMX) or sulfamethazine (SMZ) or sulfafurazole (SFZ) using the information in the absorption spectra of appropriate solutions. Beer's law was obeyed in the concentration range of 0.98-17.5 microg/ml for TMP, 0.95-17.2 microg/ml for SMX, 1.16-17.5 microg/ml for SMZ and 0.97-17.4 microg/ml for SFZ. The first derivative (1D) bivariate algorithm method involves the use of four calibration curves: two for each compound at two different wavelengths, selected by Kaiser's method. Similarly, the first derivative ratio spectrophotometry employs the linear relationship between the ratio spectra of the analytes and the concentration range. The results were compared with those obtained by PLS multivariate calibration. The calibration models from PLS were pre-treated by orthogonal signal correction and evaluated by cross-validation using the 'SIMCA-P 9' software. Synthetic mixtures of TMP and sulfonamides were used in five different sets for the validity of the calibrations. Mean recoveries for derivative ratio, derivative bivariate and PLS methods were found to be between 99.7% and 102.0% for TMP, 99.4% and 100.2% for SMX, 99.3% and 101.0% for SMZ and 98.1% and 102.3% for SFZ. The calibrations of the three methods were successfully applied to the assaying and dissolution of placebo and commercial tablets without any prior separation. More than 85% of TMP, SMX and SMZ were dissolved within 15 min. For SFZ, only 85% of the compound was dissolved after 60 min. In this study, the three spectrophotometric methods can be satisfactorily used for the quantitative analysis and for dissolution tests of multicomponent dosage forms.

Algorithms↗
PubMed1990

Effect of sulfonamides and 4-MET on adhesion to tooth substrates.

Adhesion of a composite to tooth substrates was studied. The bonding liner was a mixture: camphorquinone, 0.5%; one of four sulfonamides (A, B, C, and D), 0.5%; 4-methacryloxyethyl trimellitate (4-MET), 0, 2, and 5%; in triethyleneglycol dimethacrylate (TEGDMA). The best tensile bond strength to bovine dentin treated with 0.3 M EDTA 2 Na-0.2 M EDTA FeNa (EDTA 3-2) was 7.5 MPa. The bond strength to bovine dentin decreased with the addition of 4-MET. The bond strength to bovine enamel treated with 65% phosphoric acid (H3PO4) was 12.0 MPa. The tensile bond strength to bovine enamel treated with EDTA 3-2 was lower than that to enamel treated with 10% citric acid-3% ferric chloride (10-3) and with H3PO4. The polymerization of these liners was characterized by differential scanning calorimetry (DSC). The photocurable bonding liner studied was adequate for clinical studies.

Acid Etching, Dental↗
PubMed1980

Automated analysis of indapamide in drug-rodent food mixtures.

Indapamide, an antihypertensive agent, is an aryl sulfonamide that inhibits carbonic anhydrase in vitro but not in vivo. An assay was developed for indapamide in drug-rodent food mixtures that utilizes this inhibitory effect. Indapamide was extracted from the mixtures with methanol, and an aqueous dilution of the extract was sampled by a continuous-flow system. In the system, the drug was extracted with butanol and then back-extracted into alkali. This solution was neutralized, buffered, and mixed with bovine erythrocyte carbonic anhydrase. The substrate, p-nitrophenyl acetate, was added, the solution was incubated, and the amount of p-nitrophenol formed was measured. The assay was sensitive to 20 micrograms of indapamide/g of food, and 20 unknown samples could be analyzed per hour on the continuous-flow system. It is possible that the method could be extended to the analysis of other toxicological test substances that inhibit carbonic anhydrase in vitro.

Animal Feed↗
PubMed2001

A solvent used for antiepileptic drugs increases serum and brain zonisamide concentrations in seizure-susceptible el mice.

Effects of a solvent mixture commonly used to dissolve antiepileptic drugs on the anticonvulsive effect as well as serum and brain concentrations of zonisamide (ZNS), a sulfonamide derivative, were investigated. The solvent mixture consisted of propylene glycol (PG, 40%) and ethanol (10.5%) in saline (PES). Intraperitoneal administration of ZNS at 25, 50, and 75 mg/kg dissolved in PES suppressed seizures in the EL strain of mice more effectively than the same doses of ZNS in saline. Serum and brain concentrations of the drug were significantly higher with PES than with saline as the vehicle for administration. At a dose of 75 mg/kg ip, both serum and brain ZNS concentrations in mice treated with ZNS in PES remained significantly higher than concentrations in mice treated with ZNS in saline from 1 to 6 hours after injection. PES mixtures including PG may not be suitable solvents for antiepileptic drugs in experiments investigating anticonvulsive effects.

Journal Article↗
PubMed2005

Cross-coupling of sulfonamide antimicrobial agents with model humic constituents.

The oxidative cross-coupling of sulfonamide antimicrobials to constituents of natural organic matter was investigated. Sulfonamide antimicrobials were incubated with surrogate humic constituents in the absence and presence of phenoloxidases (viz., peroxidase, laccase, and tyrosinase) or acid birnessite. Substituted phenols were chosen as simple model constituents to determine the structures in humic substances important for cross-coupling reactions. The extent of sulfonamide transformation was evaluated by the disappearance of the parent compound from solution. Incubation with phenoloxidases in the absence of substituted phenols resulted in little or no sulfonamide transformation. In contrast to this, direct oxidation of sulfonamides by acid birnessite was significant. Inclusion of o-diphenols and 2,6-dimethoxyphenols in reaction mixtures resulted in significant phenoloxidase-mediated transformation of sulfonamides and enhanced antimicrobial transformation in the presence of acid birnessite. Phenolic compounds with other substitution patterns were less effective in promoting sulfonamide transformation. Nuclear magnetic resonance spectroscopy experiments provided direct evidence of peroxidase-mediated covalent cross-coupling of sulfamethazine with syringic and protocatechuic acids. Our results indicate that sulfonamide antimicrobials may be chemically incorporated into humic substances. This may result in their diminished mobility, bioavailability, and biological activity.

Anti-Infective Agents↗
PubMed2001

Phage derived peptides for targeting of doxorubicin conjugates to solid tumours.

Barriers are frequently hampering targeting of drugs and toxins to solid tumours and their microenvironment. Nano-conjugates are low molecular weight conjugates of a small drug or toxin and a targeting ligand coupled through a cleavable linker group. They offer potential advantages for tumour specific delivery in diffusion-limited situations. We have exploited fd phage-derived peptides for the targeting of low molecular weight drug conjugates to solid tumours. As a model we have chosen doxorubicin conjugates targeted to the transferrin receptor (TfR). A library of phage expressing a cyclic nona-peptide was panned against TfR. The apparent affinity of phages determined by surface plasmon resonance (SPR) increased with each cycle of the panning procedure. After five rounds approximately 80% of phages expressed the same peptide, which mediated a 30-50-fold increased receptor specific cellular uptake of the phages. The corresponding peptide was synthesised using solid phase peptide chemistry on a sulfonamide based safety catch resin. Crude mixtures of the peptide, as well as transferrin itself, were able to inhibit the phage uptake significantly. The doxorubicin conjugate of the peptide containing a cleavable linker was prepared and endosomal uptake confirmed by fluorescence microscopy.

Antibiotics, Antineoplastic↗
PubMed1994

[ANSA analysis. IV. Specificity spectra in characterizing proteases and mixtures of them].

ANSA-analysis was used for characterization of proteases and their mixtures, such as snake venoms. The method is based on the cleavage by proteases of mixtures of competing chromogenic substrates containing substituted aminonaphtalenesulfonamide (ANSA) detectable groups. All detectable ANSA groups in the substrate mixtures have non-identical modifiers, one or two substituents in the sulfonamide fragment and can be determined by chromatographic methods. To identify venoms, a mixture of six peptide substrates cleaved at the Arg-ANSA bond was proposed. Hydrolysis of this substrate mixture catalyzed by the venoms of different Crotalidae and Viperidae species gave characteristic chromatograms (ANSA spectra) for each tested sample. A method for quantitative description of differences in ANSA spectra has been proposed. Each ANSA spectrum can be presented as a vector going from the origin of the coordinated axes to a point in an n-dimensional space (n is the number of assayed ANSA products of proteolysis) with peak squares of corresponding ANSA as coordinates. The similarity between two ANSA spectra will then be characterized by angle between their vectors.

Amino Acid Sequence↗
PubMed1965

STIMULANT EFFECTS OF A SULFONAMIDE PREPARATION, SULFAPHENAZOLE, ON THE CENTRAL NERVOUS SYSTEM IN RATS.

Sulfaphenazole (Orisul), which had been reported to cause a convulsant syndrome in young European children, lowered the electroshock threshold in rats when administered in the form of tablets or suspension. This effect was not obtained with a sample of sulfaphenazole pure drug or with several other long-acting oral sulfonamide preparations, but was obtained with a mixture of impurities which had been found in the same lot of Orisul that had reportedly caused the convulsant syndrome. A change in the method of manufacture now provides a product which is free from these impurities.

Central Nervous System↗
PubMed1994

[ANSA analysis. V. Secondary specificity of peptidases to the structure of detected groups of aminonaphthalenesulfamide chromogenic substrates].

Mixtures of competing aminonaphthalenesulfonamide (ANSA) substrates can be used for identifying secondary substrate specificity of peptidases and their mixtures. All substrates in the mixture had identical amino acid residues; however, cleaved ANSA differed in chromatographic mobilities due to differences in the substituent in the sulfonamide residue. ANSA generated by limited proteolysis of the substrate mixture by the enzyme preparation were detected chromatographically. The chromatogram obtained (the ANSA spectrum) was characteristic of each enzyme or enzyme-containing preparation. Using arginyl-ANSA mixtures, informative ANSA spectra suitable for enzyme identification were obtained. The correlations between the structure of the substituents in the SONR1R2 group of ANSA and the efficiency of substrate hydrolysis were studied. The method was used to identify snake venoms.

Amino Acid Sequence↗
PubMed1971

Inhibition of Pseudomonas aeruginosa by hyperbaric oxygen. I. Sulfonamide activity enhancement and reversal.

To elucidate an explanation for in vitro sulfonamide enhancement by high-pressure oxygen (HPO) and the reported absence of enhancement with in vivo therapy, Pseudomonas aeruginosa cultures were exposed to selected antifolate antimicrobials in the presence of 1.87 atm absolute of O(2) and compared with non-HPO treated controls. Under these conditions, HPO alone retarded growth. Trimethoprim, a non-sulfonamide which inhibits dihydrofolate reductase, was not bactericidal, nor did HPO enhance existent bacteriostatic activity. The sulfonamide, sulfisozazole, was not bactericidal, but HPO enhanced bacteriostatic activity twofold; bacteriostasis was mitigated in HPO-treated and control cultures by p-aminobenzoate but not by a mixture of compounds involved in folate-mediated "1-C" biosynthesis. Mafenide, a unique sulfonamide, at high concentrations with HPO, was synergistically bactericidal; non-HPO-treated cultures were bacteriostatically inhibited. Bacteriostatic activity of lower mafenide concentrations was also enhanced at least twofold by HPO. These inhibitory effects of mafenide, acting with or without HPO, were mitigated by the above mixture, but not by p-aminobenzoate. This may explain the lack of in vivo HPO-mafenide enhancement in burn-wound sepsis where exudates would contain such a mixture. Lastly, HPO itself was largely bactericidal at 2.87 atm absolute of O(2). This was reversed to various degrees by the above mixture, or its components, or by folic, folinic, or p-aminobenzoic acids. These in vitro interactions suggest HPO per se may act at the same site as some sulfonamides to inhibit folate synthesis (not primarily at the dihydrofolate reductase level), or coenzyme functions of folate, or both.

Aminobenzoates↗
PubMed1952

Treatment of impetigo with sulfonamide-urea powder.

Sulfonamides can be used in the treatment of impetigo with vastly increased safety and with more effectiveness in powder rather than ointment form when combined with urea powder in a ratio of approximately three parts of sulfonamide to one of urea. Of 701 patients treated with such a mixture, 95.6 per cent were cured within a week. The only complication was local dermatitis which occurred in 0.57 per cent of patients. This compares favorably with results obtained with newer and expensive drugs which usually have the disadvantage of being used in a greasy vehicle. The low incidence of sensitivity reaction to the sulfonamide-urea powder is perhaps ascribable in part to the avoidance of a greasy vehicle.

Excipients↗
PubMed2005

Extraction and determination of sulfonamides, macrolides, and trimethoprim in sewage sludge.

Pressurized liquid extraction (PLE) was optimized and validated for the determination of sulfonamide and macrolide antimicrobials and trimethoprim in sewage sludge samples. A mixture of water/methanol (50:50, v/v) was found as the most efficient extraction solvent. A temperature of 100 degrees C and a pressure of 100 bar were chosen for extraction. Two cycles of 5 min each efficiently extracted at least 97% of the total extractable amount of all studied analytes from activated sludge. The limits of quantification (S/N= 10) varied between 3 and 41 microg/kg dry weight (dw) and the relative recoveries ranged between 78 and 142%. Additionally, the influence of pH and different LC/MS/MS systems on the absolute recoveries was assessed. Of the investigated antimicrobials sulfapyridin, sulfamethoxazole, trimethoprim, azithromycin, clarithromycin and roxithromycin were detected in municipal sewage sludge samples. Concentrations in activated sludge ranged up to 197 microg/kgdw. In comparison, results obtained by ultrasonic solvent extraction were significantly lower for sulfonamides and in tendency lower for macrolides.

Chromatography, Liquid↗
PubMed2003

Competing sulfonylation and phosphonylation following rearrangement of an O-sulfonyl-N-phosphinoylhydroxylamine with tert-butylamine: demonstration of a phosphonamidic-sulfonic anhydride intermediate and 18O-labelling evidence on how it may be formed.

Reaction of R(Ph)P(O)N HOSO2Bn (R = PhMeCH) with Bu(t)NH2 in CH2Cl2 gives a mixture of RP(O)(NHPh)-NHBu(t) and Bu(t)NHSO2Bn, the proportion of the sulfonamide increasing steadily (14.6% to 32.9%) as the concentration of amine is reduced (8.0 to 0.2 mol dm(-3)). Apparently the phenyl and sulfonate groups in the substrate become transposed, giving a phosphonamidic-sulfonic anhydride RP(O)(NHPh)OSO2Bn which then reacts at the phosphorus or sulfur atom to give the final products; an authentic sample of the anhydride gives similar mixtures of products. Substrate labelled with 18O in the sulfonyl position (57 mol% one 18O atom) gives sulfonamide containing most but not all of the label (43.7 mol% one 18O atom with 2.0 mol dm(-3) amine). This implies partial equilibration of the three sulfonate oxygen atoms during rearrangement, or after the anhydride intermediate has been formed.

Journal Article↗
PubMed2000

Tributyltin induces cytoskeletal alterations in the colonial ascidian Botryllus schlosseri phagocytes via interaction with calmodulin.

In the colonial ascidian Botryllus schlosseri, tributyltin (TBT), a powerful antifouling biocide, acts as immunotoxic xenobiotic since, at a sublethal concentration (10 µM), it causes an irreversible and significant decrease in in vitro yeast phagocytosis, associated with considerable changes in the shape of phagocytes, which withdraw their pseudopodia and become spherical, due to structural damage of cytoskeletal components. The addition of TBT to the culture medium causes a significant decrease in the amoebocytic index, i.e. the percentage of amoeboid-shaped haemocytes, and prolonged washing in sea water never succeeds in restoring amoeboid shape. In these cytoskeletal alterations, F-actin undergoes extensive depolymerisation, resulting in the absence of FITC-phalloidin fluorescence. Microtubules are not recognisable as single filaments with anti-alpha-tubulin immunofluorescence, although the centrosome is not affected. The addition of increasing exogenous calmodulin (CaM) concentrations (from 20 to 120 µM) after incubation in TBT determines a significant increase in the amoebocytic index, although it is not able to bring it to that of controls, suggesting that CaM in the medium in any case externally exerts an influence on haemocytes pretreated with TBT. The copresence of TBT and exogenous CaM at concentrations higher than 80 µg/ml restores the amoebocytic index and cytoskeletal morphology. The latter appears complete for microtubules and partial for microfilaments. Experiments with isodynamic mixtures of TBT and specific CaM inhibitors, i.e. chlorpromazine (CPZ) and N-(6-aminohexyl)-5-chloronaphtalene-1-sulfonamide (W-7), reveal the synergistic effect of antagonism, indicating competition for the same site - a Ca(2+)-CaM hydrophobic region - by both interacting substances and, therefore, the formation of a TBT-CaM complex. Instead, isodynamic mixtures with thapsigargin, an inhibitor of Ca(2+)-ATPase of the endoplasmic reticulum, have an effect of potentiation, suggesting that TBT indirectly interacts with this Ca(2+)-ATPase activity. We hypothesise that the main mechanism of action of TBT in B. schlosseri phagocytes is alteration of Ca(2+) homeostasis by means of direct interaction with endogenous CaM, which induces a conformational change preventing the regulative activity of CaM on Ca(2+)-ATPase. Consequently, an excess of cytosolic Ca(2+) accumulates which, together with the inhibition of CaM-dependent kinases and Ca(2+)-regulated proteins, produces extensive cytoskeletal disorganisation.

Journal Article↗