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PubMed2006

Radical graft polymerization of styrene sulfonate on poly(ethylene terephthalate) films for ACL applications: "grafting from" and chemical characterization.

The purpose of this study is to develop a reliable method of functionalizing poly(ethylene terephthalate) with bioactive polymers to produce a "biointegrable" artificial anterior cruciate ligament. Radical graft polymerization of the sodium salt of styrene sulfonate (NaSS) onto poly(ethylene terephthalate) (PET) films was performed using the "grafting from" technique. Prior to the grafting, the surfaces of poly(ethylene terephthalate) films were activated by ozonation to generate peroxide and hydroperoxide reactive species on the PET film surfaces. The radical polymerization of NaSS was initiated by thermal decomposition of the hydroperoxides. The grafted PET surfaces were characterized by a toluidin blue colorimetric method, X-ray photoelectron spectroscopy, contact angle measurements, and atomic force microscopy. The influence of ozonation time, monomer concentration, and temperature on NaSS grafting ratios was examined. A total of 30 min of ozonation followed by grafting from a 15% NaSS solution at 70 degrees C for 90 min or more resulted in attachment of poly(NaSS) chains to the PET film surfaces.

Biocompatible Materials↗
PubMedDate not supplied

Comparison of protein fouling on heat-treated poly(vinyl alcohol), poly(ether sulfone) and regenerated cellulose membranes using diffuse reflectance infrared Fourier transform spectroscopy.

Poly(vinyl alcohol) (PVA) membranes for ultrafiltration were fabricated by heat-treatment to separate macromolecules from microsolutes. PVA is a hydrophilic polymer with good mechanical properties because of its semicrystalline structure. The membranes were heat-treated at 100 degrees C for 1 h to increase their crystallinity and thereby their mechanical strength. The mechanical strength of the membranes was evaluated using a dynamic mechanical analyzer by measuring their compressive and tensile moduli. Membrane selectivities and protein fouling of heat-treated PVA membranes were compared to the commercial poly(ether sulfone) (PeS) and regenerated cellulose membranes. Myoglobin from horse skeletal muscle was used as a model protein, and L-tryptophan was used as a model microsolute. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to identify protein fouling on the surfaces of these membranes under flow and nonflow conditions. It was found from the selectivity and DRIFTS studies that PVA membranes were more resistant to fouling than regenerated cellulose and PeS membranes.

Adsorption↗
PubMedDate not supplied

A note concerning acetate activation of peroxidative activity of catalases using 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid as a substrate.

Beef liver catalases showed peroxidative activity using 2,2'-azino-bis-(3-ethylbenzthiazoline)-6-sulfonic acid as the electron donor and hydrogen peroxide as the acceptor at a pH of 5. This activity was not observed at pH 7. The reaction depended on acetate concentration, although succinate and propionate could partly replace the acetate as a catalyst. Other haem proteins also catalyzed a peroxidative effect. The reaction using syringaldazine or the coupling between dimethylaminobenzoic acid and 3-methyl-2-benzothiazolinone hydrazone was less effective and less sensitive. Evidence is presented that the reaction is associated with a conformational change of the catalase.

Animals↗
PubMed2001

Perfluorooctane sulfonate in fish-eating water birds including bald eagles and albatrosses.

Perfluorooctane sulfonate (PFOS) was measured in 161 samples of liver, kidney, blood, or egg yolk from 21 species of fish-eating water birds collected in the United States including albatrosses from Sand Island, Midway Atoll, in the central North Pacific Ocean. Concentrations of PFOS in the blood plasma of bald eagles collected fromthe midwestern United States ranged from 13 to 2,220 ng/mL (mean: 330 ng/mL), except one sample that did not contain quantifiable concentrations of PFOS. Concentrations of PFOS were greater in blood plasma than in whole blood. Among 82 livers from various species of birds from inland or coastal U.S. locations, Brandt's cormorant from San Diego, CA, contained the greatest concentration of PFOS (1,780 ng/g, wet wt). PFOS was also found in the sera of albatrosses from the central North Pacific Ocean at concentrations ranging from 3 to 34 ng/mL. Occurrence of PFOS in birds from remote marine locations suggests widespread distribution of PFOS and related fluorochemicals in the environment.

Animals↗
PubMed2002

Chiral PCB methyl sulfones in rat tissues after exposure to technical PCBs.

PCB methyl sulfones (MeSO2-PCBs) are lipophilic PCB metabolites known to exhibit selective tissue retention properties in wildlife and humans. The aim of this study was to investigate the presence of atropisomers of MeSO2-PCB congeners in tissues of rats exposed to a technical PCB product, Clophen A50. Changes in the enantiomer fractions (EFs) of the MeSO2-PCB atropisomers after exposure were also determined. Liver, lung, and adipose tissue from rats dosed with Clophen A50 were analyzed for the MeSO2-PCB atropisomers of 3-methylsulfonyl-2,2',4',5,6-pentachlorobiphenyl (5-MeSO2-CB91), 4-methylsulfonyl-2,2',3,4',6-pentachlorobiphenyl (4-MeSO2-CB91), 3-methylsulfonyl-2,2',3',4',5,6-hexachlorobiphenyl (5'-MeSO2-CB132), 4-methylsulfonyl-2,2',3,3',4',6-hexachlorobiphenyl (4'-MeSO2-CB132), 3-methylsulfonyl-2,2',4',5,5',6-hexachlorobiphenyl (5-MeSO2-CB149), and 4-methylsulfonyl-2,2',3,4',5',6-hexachlorobiphenyl (4-MeSO2-CB149). In all tissues analyzed, especially lung, the para-MeSO2-PCBs were more abundant than the meta-MeSO2-PCBs. The concentration ratio was higher for 4-MeSO2-CB149 versus 5-MeSO2-CB149 than for the corresponding ratio 4-/5-MeSO2-CB91 and 4'-/5'-MeSO2-CB132. Enantioselective MeSO2-PCB analysis of the lung samples showed an excess and dominance of the second eluting atropisomer of 4-MeSO2-CB149. In both lung and adipose tissues, small amounts of the first eluting atropisomer of 5-MeSO2-CB149 was present, but this atropisomer was not detected in the liver. No significant time-dependent changes in the EFs of 4-MeSO2-CB91, 5'-MeSO2-CB132, 4'-MeSO2-CB132, 5-MeSO2-CB149, and 4-MeSO2-CB149 atropisomers were found for either lung, liver, or adipose tissue. The results of the present study suggest that enantioselective formation occur for both meta- and para-MeSO2-PCBs.

Adipose Tissue↗
PubMed2006

Synthesis of zinc, copper, nickel, cobalt, and iron complexes using tris(pyrazolyl)methane sulfonate ligands: a structural model for N,N,O binding in metalloenzymes.

Ligands of intermediate steric bulk were designed to mimic metalloenzymes with histidine and carboxlyate binding sites. The reaction between tris(3-isopropylpyrazolyl)methane and butyllithium followed by SO3NMe3 in THF yielded the new ligand lithium tris(3-isopropylpyrazolyl)methane sulfonate (LiTpmsiPr). Various metal salts reacted with LiTpmsiPr to give the octahedral complexes M(TpmsiPr)2 (M = Zn, Cu, Ni, Co, Fe) in which each ligand has N,N,O binding to the metal. In the reaction between LiTpmsiPr and ZnCl2, in addition to the major product Zn(TpmsiPr)2, [LiTpmsiPrZnCl2].2THF was also formed as a minor product with a tetrahedral zinc atom coordinated to either N,N,Cl,Cl in the solid phase or N,N,N,Cl in acetonitrile solution. Although TpmsiPr is coordinatively flexible and can act as a bipodal or tripodal ligand, it appears to favor the formation of octahedral L2M complexes.

Binding Sites↗
PubMed2003

Application of the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation assay to a flow injection system for the evaluation of antioxidant activity of some pure compounds and beverages.

The 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(*)(+)) assay was adapted to a flow injection (FI) system to obtain a sensitive and rapid technique for the monitoring of antioxidant activity of pure compounds and complex matrixes, such as beverages and food extracts. The FI system includes a HPLC pump that flows the mobile phase (a solution of ABTS(*)(+) in ethanol) through a 20 microL loop injector, a single bead string reactor filled with acid-washed silanized beads, a delay coil and a photodiode array UV-visible detector. The technique was very sensitive, with limits of detection and of quantification of 4.14 and 9.29 micromol of Trolox/L, respectively, and demonstrated high repeatability and reproducibility. The proposed technique was then applied to the evaluation of the antioxidant activity of some pure compounds, demonstrating good agreement with published data obtained by the original spectrophotometric ABTS(*)(+) assay. Finally, the total antioxidant activity of 10 beverages was determined by both the proposed and the original method. The values ranged from 0.09 mmol L(-)(1) for cola to 49.24 mmol L(-)(1) for espresso coffee and did not result significantly different from those obtained by the original spectrophotometric ABTS(*)(+) assay (Student's paired t-test: t = 1.4074, p = 0.1929). In conclusion, the proposed FI technique seems suitable for the direct, rapid and reliable monitoring of total antioxidant activity of pure compounds and beverages and, due to the ability to operate in continuous, it allows the analysis of about 30 samples h(-)(1) making the assay particularly suitable for large screening of total antioxidant activity in food samples.

Antioxidants↗
PubMed2003

Pseudoperoxidase activity of myoglobin: kinetics and mechanism of the peroxidase cycle of myoglobin with H2O2 and 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonate) as substrates.

Using 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) as substrate, it has been shown that the increased peroxidase activity for decreasing pH of myoglobin activated by hydrogen peroxide is due to a protonization of ferrylmyoglobin, MbFe(IV)=O, facilitating electron transfer from the substrate and corresponding to pK(a) approximately 5.2 at 25.0 degrees C and ionic strength 0.16, rather than due to specific acid catalysis. On the basis of stopped flow absorption spectroscopy with detection of the radical cation ABTS(.+), the second-order rate constant and activation parameters for the reaction between MbFe(IV)=O and ABTS were found to have the values k = 698 +/- 32 M(-1) s(-1), DeltaH# = 66 +/- 4 kJ mol(-1), and DeltaS# = 30 +/- 15 J mol(-1) K(-1) at 25.0 degrees C and physiological pH (7.4) and ionic strength (= 0.16 M NaCl). At a lower pH (5.8) corresponding to the conditions in meat, values were found as follows: k = 3.5 +/- 0.3 x 10(4) M(-1) s(-1), DeltaH# = 31 +/- 6 kJ mol(-1), and DeltaS# = -53 +/- 19 J mol(-1) K(-1), indicative of a shift from outersphere electron transfer to an innersphere mechanism. For steady state assay conditions, this shift is paralleled by a shift from saturation kinetics at pH 7.4 to first-order kinetics for H2O2 as substrate at pH 5.8. In contrast, the activation reaction between myoglobin and hydrogen peroxide was found at 25.0 degrees C to be slow and independent of pH with values of 171 +/- 7 and 196 +/- 19 M(-1) s(-1) found at physiological and meat pH, respectively, as determined by sequential stopped flow spectroscopy, from which a lower limit of k = 6 x 10(5) M(-1) s(-1) for the reaction between perferrylmyoglobin, .MbFe(IV)=O, and ABTS could be estimated. As compared to the traditional peroxidase assay, a better characterization of pseudoperoxidase activity of heme pigments and their denatured or proteolyzed forms is thus becoming possible, and specific kinetic effects on activation, substrate oxidation, or shift in rate determining steps may be detected.

Benzothiazoles↗
PubMed2006

Modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (abts) method to measure antioxidant capacity of Selected small fruits and comparison to ferric reducing antioxidant power (FRAP) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) methods.

The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. Of the phenolic compounds examined, chlorogenic and caffeic acids exhibited the most complex reaction kinetics and reaction rates that precluded end point analysis while gallic acid and quercetin reached stable end points. All fruit extracts exhibited complex and varied kinetics and required long reaction times to approach an end point. Because the antioxidant capacity of fruit extracts is a function of the array of individual antioxidants present, accurate comparisons among fruit samples require that reaction times be standardized and of sufficient length to reach steady state conditions and that more than one assay be used to describe the total antioxidant activity of fruit samples.

Antioxidants↗
PubMed1976

Biologically oriented organic sulfur chemistry. 14. Antiinflammatory properties of some aryl sulfides, sulfoxides, and sulfones.

To extend earlier work, to examine the possibility that certain sulfoxides might serve as counterparts of amines in receptor-site interactions, and to add to the little information available about sulfoxides in medicinal chemistry, sulfoxides were prepared of the general structure XArS(O)C6H4(CHR)nCO2H, together with the sulfides and some of the sulfones. The products were evaluated as antiinflammatory agents by carrageenan-edema inhibition and uv-erythema inhibition. Four of the compounds had activity roughly comparable to aspirin or phenylbutazone in one or the other of these assays (2a-c, 3b). Sulfoxides did not seem especially promising as a class and usually were less active than the corresponding sulfides. The two most interesting compounds in these assays, o-(phenylthio)phenylacetic acid (2b) and its sulfoxide 3b, had no significant activity in adjuvant arthritis. Hydrogen-bonding effects are indicated in certain of the acids by their absence in the corresponding esters.

Animals↗
PubMed1987

A quantitative structure-activity relationship analysis of some 4-aminodiphenyl sulfone antibacterial agents using linear free energy and molecular modeling methods.

A set of 36 congeneric 4-aminodiphenyl sulfones with measured inhibition potencies of dihydropteroate synthase were studied by using both linear free energy and molecular modeling methods. The goals of the investigation were to identify the "active" conformation for these compounds as inhibitors and, correspondingly, to contruct a quantitative structure-activity relationship (QSAR). These molecules are quite flexible and possess multiple conformational energy minima. Application of molecular shape analysis (MSA), using all intramolecular energy minima as part of the analysis, was not successful in generating a QSAR. However, the calculated intramolecular conformational entropy of these compounds was found to correlate with inhibition potency leading to a highly significant QSAR. Inhibition potency increases as entropy decreases. A decrease in entropy enhances the population of specific, symmetry-related minimum-energy conformations. In this indirect way, it was possible to postulate an "active" conformation. This investigation illustrates that specific knowledge of the "active" shape of a molecule may not provide the information needed to quantitatively explain the observed structure-activity relationship.

Anti-Bacterial Agents↗
PubMed1987

Resolution, absolute configuration, and cholinergic enantioselectivity of (-)- and (+)-c-2-methyl-r-5-[(dimethylamino)methyl]-1,3-oxathiolane t-3-oxide methiodide and related sulfones.

As a continuation of previous studies on chiral cholinergic agonists carrying a 1,3-oxathiolane nucleus, the enantiomers of c-2-methyl-r-5-[(dimethylamino)methyl]-1,3-oxathiolane t-3-oxide methiodide ((+)- and (-)-1) and of cis-2-methyl-5-[(dimethylamino)methyl]-1,3-oxathiolane 3,3-dioxide ((+)- and (-)-2) were obtained and their absolute configurations established by synthesis. The cholinergic potency of the four isomers was evaluated in vitro on guinea pig ileum and frog rectus abdominis models, and the results show that (-)-1, which has the same absolute configuration as L-(+)-muscarine, is a selective and potent muscarinic agent. The (+)-1 enantiomer is some hundred times less potent than (-)-1 on the muscarinic guinea pig ileum while, on the same tissue, the corresponding sulfone derivatives ((+)- and (-)-2) show no enantioselectivity.

Animals↗
PubMed1987

Synthesis, chemical reactivity, and antileukemic activity of 5-substituted 6,7-bis(hydroxymethyl)pyrrolo[1,2-c]thiazole biscarbamates and the corresponding sulfoxides and sulfones.

A series of bis(N-methylcarbamate) and bis[N-(2-propyl)carbamate] derivatives of 5-substituted 6,7-bis(hydroxy-methyl)pyrrolo[1,2-c]thiazoles was prepared. The compounds were tested for activity in vivo against P388 lymphocytic leukemia, and the chemical reactivities of the compounds were compared by using the model nucleophile 4-(4-nitrobenzyl)pyridine (NBP). The 5-(3,4-dichlorophenyl)-substituted biscarbamates 6b, 8b, and 12b were inactive and unreactive toward NBP. The 5-methyl-substituted biscarbamates 6a, 7a, 8a, 9a, 12a, and 13a were all active against murine P388 lymphocytic leukemia. The chemical reactivities of the active compounds depended on the oxidation state of the sulfur. The reactivity toward NBP followed the order S greater than SO much greater than SO2. The sulfones 12a and 13a are the most active compounds in this series, and their lack of reactivity toward NBP led to the suggestion that 12a and 13a are activated in vivo.

Animals↗
PubMed1988

Methotrexate analogues. 32. Chain extension, alpha-carboxyl deletion, and gamma-carboxyl replacement by sulfonate and phosphonate: effect on enzyme binding and cell-growth inhibition.

Analogues of methotrexate (MTX) and aminopterin (AMT) with aminophosphonoalkanoic, aminoalkanesulfonic, and aminoalkanephosphonic acid side chains in place of glutamate were synthesized and tested as inhibitors of folylpolyglutamate synthetase (FPGS) from mouse liver. The aminophosphonoalkanoic acid analogues were also tested as inhibitors of dihydrofolate reductase (DHFR) from L1210 murine leukemia cells and as inhibitors of the growth of MTX-sensitive (L1210) and MTX-resistant (L1210/R81) cells in culture. The optimal number of CH2 groups in aminophosphonoalkanoic acid analogues of AMT was found to be two for both enzyme inhibition and cell growth inhibition but was especially critical for activity against FPGS. Deletion of the alpha-carboxyl also led to diminished anti-FPGS activity in comparison with previously studied homocysteic acid and 2-amino-4-phosphonobutyric acid analogues. In the aminoalkanesulfonic acid analogues of MTX without an alpha-carboxyl, anti-FPGS activity was low and showed minimal variation as the number of CH2 groups between the carboxamide and sulfonate moieties was changed from one to four. In similar aminoalkanephosphonic acid analogues of MTX, anti-FPGS activity was also low, was comparable for two and three CH2 groups between the carboxamide and phosphonate moieties, and was diminished by monoesterification of the phosphonate group. These effects demonstrate that the alpha-carboxyl group of folate analogues is involved in binding to the active site of FPGS, and that an alpha-carboxyl group should be retained as part of the structure of FPGS inhibitors.

Aminopterin↗
PubMed2003

Novel indolyl aryl sulfones active against HIV-1 carrying NNRTI resistance mutations: synthesis and SAR studies.

The potent anti-HIV-1 activities of L-737,126 (2) and PAS sulfones prompted us to design and test against HIV-1 in acutely infected MT-4 cells a number of novel 1- and 3-benzenesulfonylindoles. Indoles belonging to the 1-benzenesulfonyl series were found poorly or totally inactive. On the contrary, some of the 3-benzenesulfonyl derivatives turned out to be as potent as 2, being endowed with potencies in the low nanomolar concentration range. In particular, (2-methylphenyl)sulfonyl (72) and (3-methylphenyl)sulfonyl (73) derivatives showed EC(50) values of 1 nM. Introduction of two methyl groups at positions 3 and 5 of the phenyl ring of 2 furnished derivatives (80 and 83) which showed very potent and selective anti-HIV-1 activity not only against the wt strain, but also against mutants carrying NNRTI-resistant mutations at positions 103 and 181 of the reverse transcriptase gene.

Anti-HIV Agents↗
PubMed2004

Folate-synthesizing enzyme system as target for development of inhibitors and inhibitor combinations against Candida albicans-synthesis and biological activity of new 2,4-diaminopyrimidines and 4'-substituted 4-aminodiphenyl sulfones.

The paper describes the design, synthesis, and testing of inhibitors of folate-synthesizing enzymes and of whole cell cultures of Candida albicans. The target enzymes used were dihydropteroic acid synthase (SYN) and dihydrofolate reductase (DHFR). Several series of new 2,4-diaminopyrimidines were synthesized and tested as inhibitors of DHFR and compared with their activity against DHFR derived from mycobacteria and Escherichia coli. To test for selectivity, also rat DHFR was used. A series of substituted 4-aminodiphenyl sulfones was tested for inhibitory activity against SYN and the I(50) values compared to those obtained previously against Plasmodium berghei- and E. coli-derived SYN. Surprisingly, QSAR equations show very similar structural dependencies. To find an explanation for the large difference in the I(50) values observed for enzyme inhibition (SYN, DHFR) and for inhibition of cell cultures of Candida, mutant strains with overexpressed efflux pumps and strains in which such pumps are deleted were included in the study and the MICs compared. Efflux pumps were responsible for the low activity of some of the tested derivatives, others showed no increase in activity after pumps were knocked out. In this case it may be speculated that these derivatives are not able to enter the cells.

Aminopyridines↗
PubMed2006

Design, molecular modeling, synthesis, and anti-HIV-1 activity of new indolyl aryl sulfones. Novel derivatives of the indole-2-carboxamide.

Molecular modeling studies and an updated highly predictive 3-D QSAR model led to the discovery of exceptionally potent indolyl aryl sulfones (IASs) characterized by the presence of either a pyrrolidyn-2-one nucleus at the indole-2-carboxamide or some substituents at the indole-2-carbohydrazide. Compounds 7 and 9 were found active in the sub-nanomolar range of concentration in both MT-4 and C8166 cell-based anti-HIV assays. These compounds, and in particular compound 9, also showed excellent inhibitory activity against both HIV-112 and HIV-AB1 primary isolates in lymphocytes and against HIV WT in macrophages.

Anti-HIV Agents↗