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PubMedDate not supplied

Chemistry of aminoiminomethanesulfinic and -sulfonic acids related to the toxicity of thioureas.

The reactions of aminoiminomethanesulfonic acid, phenylaminoiminomethanesulfonic acid, and N,N'-diphenylaminoiminomethanesulfonic acid in aqueous media at pH 7.4, 10, and 13-14 were investigated. At neutral pH hydrolysis to the corresponding urea was the major pathway for all three compounds. At higher pH phenylaminoiminomethanesulfonic acid reacted to give phenylcyanamide in nearly quantitative yield, while N,N'-diphenylaminoiminomethanesulfonic acid gave diphenylcarbodiimide which reacted further to give N,N'-diphenylurea. At pH 10 aminoiminomethanesulfonic acid reacted with itself, eventually giving N-cyanoguanidine, while at pH 13-14, elimination to cyanamide predominated. The reactions of glycine with the aminoiminomethanesulfonic acids gave guanylated acetic acids as products. The rates of these nucleophilic substitutions of the sulfonic acid group of the aminoiminomethanesulfonic acids by the amino group of glycine decreased in the order aminoiminomethanesulfonic acid greater than phenylaminoiminomethanesulfonic acid greater than (2-methylphenyl)aminoiminomethanesulfonic acid greater than (2,6-dimethylphenyl)aminoiminomethanesulfonic acid. Higher relative rates of substitution of the aminoiminomethanesulfonic acids appear to be related to higher relative toxicities for the corresponding thioureas.

Amines↗
PubMed1999

Photosensitization of guanine-specific DNA damage by 2-phenylbenzimidazole and the sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid.

Gel sequencing experiments with end-labeled synthetic oligodeoxyribonucleotides have established that 2-phenylbenzimidazole (PBZ) and the common sunscreen constituent 2-phenylbenzimidazole-5-sulfonic acid (PBSA) function as efficient photosensitizers of DNA damage when they are exposed to UV-B (290-320 nm) radiation or natural sunlight. Although neither compound binds specifically to DNA, both are active at sub-millimolar concentrations and induce the formation of piperidine-labile cleavage sites that map almost exclusively to the positions of guanine residues. The pattern of attack on single-stranded DNA, where all guanines are modified to a similar extent, is typical of photooxidation by singlet oxygen. The involvement of singlet oxygen is consistent with the effect of quenchers and scavengers on the reaction, and is supported by the demonstration that UV-B irradiation of 2'-deoxyguanosine with PBSA in oxygenated solution generates the diagnostic compound 4, 8-dihydro-4-hydroxy-8-oxo-2'-deoxyguanosine in comparatively high yield. In contrast, the main photoinduced cleavage sites in double-helical DNA are located at the 5'-guanines of GG and (to a lesser degree) GA doublets. This characteristic behavior implies that electron transfer from DNA to the photoexcited sensitizer is the predominant mechanism in this conformation. A similar dichotomy of reactivity toward denatured and native DNA has been reported for riboflavin and certain pterin derivatives which resemble PBZ and PBSA in not binding tightly to DNA. The photosensitizing properties of PBSA could possibly detract from its fitness as a sunscreen agent.

Benzimidazoles↗
PubMed2001

Initiation and inhibition of free radical processes in H2O2-metmyoglobin (methemoglobin)-2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) systems.

Rates of free radical initiation were determined at 20 degrees C in 10 mM phosphate buffer (pH 7.4) in the systems metmyoglobin (methemoglobin)-H2O2 using 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) as the diammonium salt (ABTS). The catalytic activity of MetMb was 2-3-fold higher than that of MetHb. The process can be described by the Michaelis-Menten equation, from which effective values of Km and Vmax were calculated. Comparative kinetic studies on the inhibition of ABTS oxidation were carried out using Trolox, propylgallate (PG), polydisulfide of gallic acid (poly(DSG)), polydisulfide of (2-amino-4-nitrophenol) (poly(ADSNP)), and its conjugate with human serum albumin (HSA-poly(ADSNP)). The inhibitors were characterized by inhibition constants Ki and stoichiometric inhibition coefficients f (the number of radicals terminated by a single molecule of inhibitor). The minimum Ki and the maximum f values were obtained for poly(DSG), and in the system of MetHb-H2O2-ABTS they were 0.08 microM and 27.5, respectively. According to their antiradical activities, the inhibitors can be arranged as follows: poly(DSG) > poly(ADSNP) > PG > Trolox. PG, poly(DSG), poly (ADSNP), and its conjugate with HSA are suggested as "calibrators", i.e., inhibition standards for evaluation of antioxidant status of biological fluids in possible test systems based on the free radical-generating pair MetMb-H2O2 with ABTS as the acceptor of the active radicals.

Animals↗
PubMed2001

Biotransformation of linear alkylbenzene sulfonate (LAS) by Phanerochaete chrysosporium: oxidation of alkyl side-chain.

The white rot fungus Phanerochaete chrysosporium, which generally mineralizes substituted aromatics to CO2, transformed linear alkylbenzene sulfonate (LAS) surfactants mainly at their alkyl side chain. Degradation of LAS was evidenced by a zone of clearing on LAS-containing agar plates and colorimetric analysis of liquid cultures. Disappearance of LAS was virtually complete within 10 days in low nitrogen (2.4 mM N), high nitrogen (24 mM N) and malt extract (ME) liquid media. After 5 days of incubation in ME medium, transformation of LAS was complete at concentrations < or = 4 mg l(-1), but decreased at higher concentrations. The LAS degradation was not dependent on lignin peroxidases (LiPs) and manganese-dependent peroxidases (MnPs). Mineralization of 14C-ring-LAS to 14CO2 by P. chrysosporium was < 1% regardless of the culture conditions used. Thin layer chromatography and mass spectral analyses indicated that P. chrysosporium transformed LAS to sulfophenyl carboxylates (SPCs) through oxidative shortening of the alkyl side-chains. While LAS disappearance in the cultures was not dependent on LiPs and MnPs, transformation of the parent LAS moieties to SPCs was more extensive in low N medium that favors expression of these enzymes. The SPCs produced in LN cultures were shorter in chain- length than those produced in ME cultures. Also there was a notable shift in the relative abundance of odd and even chain length metabolites compared to the starting LAS particularly in the low N cultures suggesting the possible involvement of processes other than or in addition to beta-oxidation in the chain-shortening process.

Biotransformation↗
PubMed2004

Anti-narcoleptic agent modafinil and its sulfone: a novel facile synthesis and potential anti-epileptic activity.

We report a facile procedure to synthesize racemic modafinil (diphenylmethylsulfinylacetamide), which is now being used in pharmacotherapy, and its achiral oxidized derivative (diphenylmethylsulfonyl acetamide). Modafinil is of interest more than for its potential anti-narcoleptic activity. It has also been reported to have neuroprotective properties and may potentially be effective in the enhancement of vigilance and cognitive performance. Finally, it may also protect from subclinical seizures that have been implicated as causative factors in autistic spectrum disorders and other neurodegenerative conditions. This agent can now be synthesized simply and in larger amounts than previously, making it more readily available for testing in various research modalities. The described procedure also lends itself to production of several other amides of potential interest. We are currently in the process of synthesizing and testing several new derivatives in this series. The anticonvulsant properties of modafinil and its sulfone derivative have not previously been extensively described in the literature. It may be of interest to note that the oxidized derivative of modafinil is also nontoxic and almost as effective as an anticonvulsant as the parent.

Animals↗
PubMed2002

A new B-chain mutant of insulin: comparison with the insulin crystal structure and role of sulfonate groups in the B-chain structure.

The solution structure of a new B-chain mutant of bovine insulin, in which the cysteines B7 and B19 are replaced by two serines, has been determined by circular dichroism, 2D-NMR and molecular modeling. This structure is compared with that of the oxidized B-chain of bovine insulin [Hawkins et al. (1995) Int. J. Peptide Protein Res.46, 424-433]. Circular dichroism spectroscopy showed in particular that a higher percentage of helical secondary structure for the B-chain mutant is estimated in trifluoroethanol solution in comparison with the oxidized B-chain. 2D-NMR experiments confirmed, among multiple conformations, that the B-chain mutant presents defined secondary structures such as a alpha-helix between residues B9 and B19, and a beta-turn between amino acids B20 and B23 in aqueous trifluoroethanol. The 3D structures, which are consistent with NMR data and were obtained using a simulated annealing protocol, showed that the tertiary structure of the B-chain mutant is better resolved and is more in agreement with the insulin crystal structure than the oxidized B-chain structure described by Hawkins et al. An explanation could be the presence of two sulfonate groups in the oxidized insulin B-chain. Either by their charges and/or their size, such chemical groups could play a destructuring effect and thus could favor peptide flexibility and conformational averaging. Thus, this study provides new insights on the folding of isolated B-chains.

Amino Acid Sequence↗
PubMed2000

Quantitative structure-activity relationships: sulfonate esters in the local lymph node assay.

The biological activity of skin-sensitizing chemicals is related to their ability to react, either directly or after metabolic activation, with appropriate skin proteins. For direct acting electrophilic compounds, this ability can be modelled, using the RAI (relative alkylation index) approach, by a combination of electrophilicity and hydrophobicity parameters. The development of predictive quantitative structure-activity relationships (QSAR) models of skin sensitization, using mechanism-based physicochemical parameters, has been greatly facilitated by the introduction of the murine local lymph node assay (LLNA), which is able to describe the extent of the biological response in objective and quantitative terms. In the present work, sensitization response data in the LLNA is generated for a series of 6 sulfonate esters. An RAI-based hybrid QSAR/dose-response relationship is derived using a negative hydrophobicity coefficient in the RAI expression, to model the effect of retention of the hydrophobic test chemicals in the stratum corneum. Dose-response analyses are used to estimate EC3 and EC20 values as quantitative indices of skin sensitization potential for each compound, and regression analysis is applied to develop QSARs correlating these EC3 and EC20 values with an RAI-based parameter. The high statistical quality of these QSARs demonstrates both the consistency of the LLNA method for generating high quality skin sensitization data, and the value of the RAI approach in development of mathematical models for skin sensitization.

Alkylation↗
PubMed1997

Derivatization of amphetamine and methamphetamine with 1,2-naphthoquinone 4-sulfonic acid into solid-phase extraction cartridges. Determination of amphetamine in pharmaceutical and urine samples.

The derivatization of amphetamine and methamphetamine with 1,2-naphthoquinone-4-sulfonate (NQS) into solid-phase extraction cartridges (C18) is described. Optimum conditions were the use of carbonate-hydrogencarbonate buffer of pH 10, a 10 min reaction time at 25 degrees C and an NQS concentration of 9.6 x 10(-3) M. The accuracy and the precision of the method were tested. The results obtained with the proposed liquid-solid procedure were compared with those obtained with a traditional liquid-liquid extraction with hexane-ethyl acetate. The procedure was used to measure amphetamine in pharmaceutical and urine samples.

Amphetamine↗
PubMed1995

Automated determination of microbial peroxidase activity in fermentation samples using hydrogen peroxide as the substrate and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) as the electron donor in a flow injection system.

An automated flow injection method has been developed for the determination of microbial peroxidase activity. The substrate used was hydrogen peroxide and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS) was used as the electron donor. In the presence of hydrogen peroxide, peroxidase catalyses the dehydrogenation of ABTS, resulting in the formation of a resonance-stabilized radical cation of ABTS. The green-blue colour formed, recorded at 418 nm, is taken as a measure of the peroxidase activity. The general technical conditions and the general enzymic kinetics have been optimized. Conditions for activation and stabilization of the enzyme were found, e.g., ammonium sulfate acts as a peroxidase activator. The resulting method has a good precision, sensitivity and speed.

Autoanalysis↗
PubMed2002

2,5-dimethylphenacyl esters: a photoremovable protecting group for phosphates and sulfonic acids.

2,5-Dimethylphenacyl phosphoric and sulfonic esters release the corresponding acids upon irradiation in nearly quantitative isolated yields, with quantum yields phi = 0.71 and 0.68 in methanol, 0.09 and 0.19 in benzene. In methanol solution the reactions proceed predominantly via the (Z)-photoenol, the lifetimes of which (20 and 25 micros) were determined by laser flash photolysis. The chromophore is proposed as an excellent photoremovable protecting group for use in organic synthesis and biochemistry.

Acetophenones↗
PubMed2006

Efficient and direct synthesis of poly-substituted indeno[1,2-b]quinolines assisted by p-toluene sulfonic acid using high-temperature water and microwave heating via one-pot, three-component reaction.

Reactions of aldehydes, 1,3-indanedione and enaminones were successfully carried out using p-toluene sulfonic acid (p-TsOH) as a catalyst and high-temperature water as a solvent under microwave irradiation. This method provided several advantages such as rapid reaction times, high yields, and a simple workup procedure. In addition, a possible mechanism to account for the reaction was proposed.

Catalysis↗
PubMed2000

Effect of argatroban on trinitrobenzene sulfonic acid-induced colitis.

BACKGROUND: Recent studies have suggested that heparin is effective for treatment of inflammatory bowel disease (IBD) and its various effects (in addition to the anticoagulant effect). We evaluated the effects of argatroban as an antithrombin drug on trinitrobenzene sulfonic acid (TNB)-induced colitis, an established model of IBD. METHODS: Rats were randomly assigned to four groups in which mini-osmotic pumps containing saline (TNB-S), argatroban (TNB-A), or 100 U/kg heparin (TNB-H) were intraperitoneally implanted. Three days after the pumps were implanted, TNB was infused via the anus, and colitis was induced. After 5 days, prothrombin time (PT), activated partial prothrombin time (APTT), antithrombin III (AT-III), platelet, fibrinogen, colonic wet weight, macroscopic damage score, histological score, mucosal myeloperoxidase activity and mucosal leukotrien B4 (LTB4) levels were compared among the four groups. RESULTS: The APTT was prolonged in the heparin treatment group but only slightly prolonged in the argatroban treatment group. The platelet count and the fibrinogen level were higher in the TNB-S group than in the healthy control group and the AT-III level was slightly lower in the TNB-S group than in the healthy control group and lower still in the TNB-H group. CONCLUSIONS: The colonic wet weight was similar among the four groups while the macroscopic damage score, histological score, mucosal myeloperoxidase activity and the mucosal LTB4 level were significantly decreased in the TNB-A and TNB-H groups. Argatroban, as well as heparin may be effective for treatment of TNB-induced colitis.

Analysis of Variance↗
PubMed1969

Approximation of rotational strengths from molar rotation data and generation of rotatory dispersion curves for d-camphor-10-sulfonate.

Starting with the expression for optical rotatory dispersion in the absorption region that was arrived at by Condon, two series were considered for the purpose of achieving the experimentally observed, steeper wavelength dependence in the absorption region while retaining the established 1/lambda(2) law in regions removed from absorption. The first two terms of one series in which the second term exhibits a 1/lambda(6) wavelength dependence were found to calculate satisfactorily the optical rotatory dispersion curve of d-camphor-10-sulfonate from 400 mmu to 190 mmu when only three bands were considered. Evaluated at the extrema, the two-term expression can be approximated by a simple equation which allows calculation of the rotational strength of a nonoverlapping band by using only the wavelength and molar rotation of the extrema and the index of refraction of the solution. The rotational strengths calculated from optical rotatory dispersion data in this manner closely agree with those calculated from corresponding circular dichroism data. Thus when position and magnitude of rotatory dispersion extrema alone are reported for carbonyls, it is suggested that such published data may be converted to approximate rotational strengths.

Camphor↗
PubMed1971

Properties of squid axon membrane as revealed by a hydrophobic probe, 2-p-toluidinylnaphthalene-6-sulfonate.

A hydrophobic probe, 2-p-toluidinylnaphthalene-6-sulfonate (TNS), was introduced into the interior of a squid giant axon and fluorescene properties of the TNS-stained axon were examined under illumination with polarized ultraviolet light. A transient reduction in fluorescence was observed when the axon was stimulated electrically. The light waves contributing to this fluorescence change were found to be nearly completely polarized, indicating that the probe molecules in the membrane are highly oriented. The emission spectra of these TNS-stained axons were examined at rest and during nerve excitation. The results obtained are considered to support the view that the process of nerve excitation is accompanied by a transition of the axon membrane from a hydrophobic to a hydrophilic state.

Animals↗
PubMed1995

The 3'-terminal exon of the family of steroid and phenol sulfotransferase genes is spliced at the N-terminal glycine of the universally conserved GXXGXXK motif that forms the sulfonate donor binding site.

The guinea pig estrogen sulfotransferase gene has been cloned and compared to three other cloned steroid and phenol sulfotransferase genes (human estrogen sulfotransferase, human phenol sulfotransferase, and guinea pig 3 alpha-hydroxysteroid sulfotransferase). The four sulfotransferase genes demonstrate a common outstanding feature: the splice sites for their 3'-terminal exons are identically located. That is, the 3'-terminal exon splice sites involve a glycine that constitutes the N-terminal glycine of an invariably conserved GXXGXXK motif present in all steroid and phenol sulfotransferases for which primary structures are known. This consistency strongly suggests that all steroid and phenol sulfotransferase genes will be similarly spliced. The GXXGXXK motif forms the active binding site for the universal sulfonate donor 3'-phosphoadenosine 5'-phosphosulfate. Amino acid sequence alignment of 19 cloned steroid and phenol sulfotransferases starting with the GXXGXXK motif indicates that the 3'-terminal exon for each steroid and phenol sulfotransferase gene encodes a similarly sized C-terminal fragment of the protein. Interestingly, on further analysis of the alignment, three distinct amino acid sequence patterns emerge. The presence of the conserved functional GXXGXXK motif suggests that the protein domains encoded by steroid and phenol sulfotransferase 3'-terminal exons have evolved from a common ancestor. Furthermore, it is hypothesized that during the course of evolution, the 3'-terminal exon further diverged into at least three sulfotransferase subdivisions: a phenol or aryl group, an estrogen or phenolic steroid group, and a neutral steroid group.

Amino Acid Sequence↗
PubMed2001

Cells adapted to the proteasome inhibitor 4-hydroxy- 5-iodo-3-nitrophenylacetyl-Leu-Leu-leucinal-vinyl sulfone require enzymatically active proteasomes for continued survival.

The proteasome is the primary protease used by cells for degrading proteins and generating peptide ligands for class I molecules of the major histocompatibility complex. Based on the properties of cells adapted to grow in the presence of the proteasome inhibitor 4-hydroxy-5-iodo-3-nitrophenylacetyl-Leu-Leu-leucinal-vinyl sulfone (NLVS), it was proposed that proteasomes can be replaced by alternative proteolytic systems, particularly a large proteolytic complex with a tripeptidyl peptidase II activity. Here we show that NLVS-adapted cells retain sensitivity to a number of highly specific proteasome inhibitors with regard to antigenic peptide generation, accumulation of polyubiquitinated proteins, degradation of p53, and cell viability. In addition, we show that in the same assays (with a single minor exception), NLVS-adapted cells are about as sensitive as nonselected cells to Ala-Ala-Phe-chloromethylketone, a specific inhibitor of tripeptidyl peptidase II activity. Based on these findings, we conclude that proteasomes still have essential proteolytic functions in adapted cells that are not replaced by Ala-Ala-Phe-chloromethylketone-sensitive proteases.

Amino Acid Chloromethyl Ketones↗