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PubMed2004

Antimicrobial activity of hydrophobic xanthones from Cudrania cochinchinensis against Bacillus subtilis and methicillin-resistant Staphylococcus aureus.

Ten xanthones with one or two isoprenoid groups and a prenylated benzophenone isolated from roots of Cudrania cochinchinensis (Moraceae) were tested for their antimicrobial activities against Bacillus subtilis and methicillin-resistant Staphylococcus aureus (MRSA). Among these compounds, gerontoxanthone H exhibited considerable antibacterial activity against B. subtilis (MIC = 1.56 microg/ml). Four xanthones, gerontoxanthone I, toxyloxanthone C, cudraxanthone S, and 1,3,7-trihydroxy-2-prenylxanthone, showed weak antibacterial activity against the bacterium (MICs = 3.13-6.25 microg/ml). These compounds also exhibited similar MIC values against methicillin-sensitive S. aureus, MRSAs, and Micrococcus luteus.

Anti-Infective Agents↗

PubMed2004

Substituent-dependent reactivity in the photodimerization of N-substituted dibenz[b,f]azepines.

The photoprocesses of a series of N-substituted dibenz[b,f]azepines (iminostilbenes) were studied by absorption and emission spectroscopy, by laser flash photolysis, and by preparative irradiation with NMR analysis. In solutions, 2pi+2pi photodimers of N-cyano and N-acyl dibenzazepines are formed via the triplet state upon acetone- or benzophenone-sensitized energy transfer. T-T absorption spectra were measured and absorption coefficients were determined. The triplet energy transfer is equally efficient for N-alkyl dibenzazepines, which do not dimerize. Excited states of npi* character in the latter cases are discussed to rationalize the different reactivities. In spite of negligible intersystem crossing of 21 dibenzazepine derivatives, photodimers of N-acyl and N-cyano dibenzazepines are formed upon direct excitation in concentrated solutions (0.01-0.1 mol dm(-3)) as well as in the solid state. A selective anti-configuration of the photodimers was found throughout.

Journal Article↗

PubMed2006

Insertion, reduction, and carbon-carbon coupling induced by monomeric aluminum hydride compounds bearing substituted pyrrolyl ligands.

A monomeric aluminum hydride complex bearing substituted pyrrolyl ligands, AlH[C(4)H(3)N(CH(2)NMe(2))-2](2) (1), was synthesized and structurally characterized. To further confirm the presence of Al--H bonds, the compound AlD[C(4)H(3)N(CH(2)NMe(2))-2](2) ([D]1) was synthesized by reacting LiAlD(4) with [C(4)H(4)N(CH(2)NMe(2))-2]. Compound 1 and [D]1 react with phenyl isothiocyanate yielding Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCHNPh] (2) and Al[C(4)H(3)N(CH(2)NMe(2))-2](2)[eta(3)-SCDNPh] ([D]2) by insertion. The reactions of 1 with 9-fluorenone and benzophenone generated the unusual aluminum alkoxide complexes 3 and 4, respectively, through intramolecular proton abstraction and C-C coupling. A mechanistic study shows that 9-fluorenone coordinates to [D]1 and releases one equivalent of HD followed by C-C coupling and hydride transfer to yield the final product. Reduction of benzil with 1 affords aluminum enediolate complex 5 in moderate yield. Mechanistic studies also showed that the benzil was inserted into the aluminum hydride bond of [D]1 through hydroalumination followed by proton transfer to generate the final product [D]5. All new complexes have been characterized by (1)H and (13)C NMR spectroscopy and X-ray crystallography.

Journal Article↗

PubMed2006

Intramolecular triplet energy transfer in donor-acceptor molecules linked by a crown ether bridge.

Bichromophoric compounds BP-C-NP and BP-C-NBD were synthesized with benzophenone chromophore (BP) as the donor, and 2-naphthyl (NP) and norbornadiene group (NBD) as the acceptor, respectively. Their intramolecular triplet energy transfer was examined. The bridges linking the donor and acceptors in these molecules involve a crown ether moiety complexing a sodium ion. Phosphorescence quenching, flash photolysis and photosensitized isomerization experiments indicate that intramolecular triplet energy transfer occurs with rate constants of about 3.3 x 10(5) and 4.8 x 10(5) s(-1) and efficiencies of about 33 and 42 % for BP-C-NP and BP-C-NBD, respectively. Theoretical calculations indicate that these molecules adopt conformations below room temperature which allow their two-end chromophores conducive to through-space energy transfer.

Journal Article↗

PubMed2006

Mechanistic investigations of imine hydrogenation catalyzed by cationic iridium complexes.

Complexes [IrH2(eta6-C6H6)(PiPr3)]BF4 (1) and [IrH2(NCMe)3(PiPr3)]BF4 (2) are catalyst precursors for homogeneous hydrogenation of N-benzylideneaniline under mild conditions. Precursor 1 generates the resting state [IrH2{eta5-(C6H5)NHCH2Ph}(PiPr3)]BF4 (3), while 2 gives rise to a mixture of [IrH{PhN=CH(C6H4)-kappaN,C}(NCMe)2(PiPr3)]BF4 (4) and [IrH{PhN=CH(C6H4)-kappaN,C}(NCMe)(NH2Ph)(PiPr3)]BF4 (5), in which the aniline ligand is derived from hydrolysis of the imine. The less hindered benzophenone imine forms the catalytically inactive, doubly cyclometalated compound [Ir{HN=CPh(C6H4)-kappaN,C}2(NH2CHPh2)(PiPr3)]BF4 (6). Hydrogenations with precursor 1 are fast and their reaction profiles are strongly dependent on solvent, concentrations, and temperature. Significant induction periods, minimized by addition of the amine hydrogenation product, are commonly observed. The catalytic rate law (THF) is rate = k[1][PhN=CHPh]p(H2). The results of selected stoichiometric reactions of potential catalytic intermediates exclude participation of the cyclometalated compounds [IrH{PhN=CH(C6H4)-kappaN,C}(S)2(PiPr3)]BF4 [S = acetonitrile (4), [D6]acetone (7), [D4]methanol (8)] in catalysis. Reactions between resting state 3 and D2 reveal a selective sequence of deuterium incorporation into the complex which is accelerated by the amine product. Hydrogen bonding among the components of the catalytic reaction was examined by MP2 calculations on model compounds. The calculations allow formulation of an ionic, outer-sphere, bifunctional hydrogenation mechanism comprising 1) amine-assisted oxidative addition of H2 to 3, the result of which is equivalent to heterolytic splitting of dihydrogen, 2) replacement of a hydrogen-bonded amine by imine, and 3) simultaneous H delta+/H delta- transfer to the imine substrate from the NH moiety of an arene-coordinated amine ligand and the metal, respectively.

Journal Article↗

PubMed2005

Novel lead structures for antimalarial farnesyltransferase inhibitors.

Through the combination of nitrophenylfurylacryloyl moiety which has been designed to occupy an aryl binding site of farnesyltransferase with several AA(X)-peptidomimetic substructures some novel farnesyltransferase inhibitors were obtained. Evaluation of their antimalarial activity and some initial modifications yielded a 4-benzophenone- and a sulfonamid-based novel lead for antimalarial farnesyltransferase inhibitors.

Alkyl and Aryl Transferases↗

PubMed1995

Circular dichroism of ketoprofen complexed to serum albumins: conformational selection by the protein: a novel optical purity determination technique.

Complexation of 2-(3'-benzoylphenyl)propionic acid (ketoprofen), 1, to bovine serum albumin (BSA) results in an intense negative circular dichroism in the ketonic n-->pi* band of the benzoylphenyl moiety. This high CD contrasts with the weak CD of 1-enantiomers dissolved in common solvents. Furthermore, a number of chiral and achiral molecules containing the benzophenone moiety are easily complexed to BSA: all these complexes show an intense CD at the same transition. To account for the observed CD intensities of the above molecules, it appears that BSA complexation markedly shifts the equilibrium between strongly asymmetric, antipodic conformers. Dissymmetry of these conformers is connected to the instability of a structure with phenyl rings coplanar to the carbonyl chromophore, as also indicated by molecular mechanics calculations. The magnification of the Cotton effects of the 1-antipodes, due to the protein, can be used to measure the optical purity of 1-samples with excellent precision. In contrast with BSA, human SA is unable to recognize the chirality of 1-antipodes; oleic acid cocomplexation modifies this fact as well as other features of the binding.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1988

Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: intralaboratory results for sixty-three coded chemicals tested at Litton Bionetics, Inc.

The reliability of the L5178Y TK+/- forward mutation assay as a rapid screen for genotoxicity was evaluated by testing 63 coded chemicals. Replicate treatments were used, and at least two independent experiments were performed for each test condition. The test conditions consisted of no exogenous activation, activation by Aroclor 1254-induced Fischer 344 rat liver S9 homogenate, and in some cases activation by noninduced Fischer 344 rat liver S9. The results were organized into tables that show the mutant colony counts, mutant frequency, and toxicity for each test chemical treatment, positive control treatment, and solvent negative control cultures. The repeat experiments were highly consistent and yielded contradictory evaluations for only a few of the chemicals studied. Fifty-one of the chemicals (81%) were evaluated as mutagenic under one or both of the test conditions. A range in minimum effective concentrations of almost 10(6)-fold (0.008 to 5,000 micrograms/ml) was observed among the mutagenic chemicals. Nine chemicals (14%) were considered to be nonmutagenic. Three chemicals (progesterone, p-rosaniline HCl, and 1,1,1-trichloroethane) gave responses that were not easily evaluated under any test condition: evidence for mutagenesis was obtained in some experiments but not for all repeat studies. Under nonactivation conditions, specifically, the mutagenic activities of 4,4'-bis(dimethylamino)benzophenone, progesterone, and p-rosaniline HCl remained uncertain. With S9 activation, uncertain evidence for mutagenesis was obtained for 2-naphthylamine, progesterone, and 1,1,1-trichloroethane. In some cases, changes in the treatment conditions could lead to different evaluations of the mutagenic activity, and these possibilities are discussed in the descriptive evaluations of each chemical. Comparisons of the observed responses with published results were possible for 29 of the compounds and yielded highly confirmatory evaluations.

Animals↗

PubMed1991

Cytotoxicity of a BIS-GMA dental composite before and after leaching in organic solvents.

Cell culture techniques were used to determine the source of cytotoxic agents in a commercial BIS-GMA composite. The material was polymerized according to the manufacturer's directions and leachable components were removed by room temperature extraction in ethanol, chloroform, or toluene. The leachable components in the extracts were identified using infrared spectrographic analysis. Thin layer chromatographic analysis was used to determine the number of constituents. These constituents were separated by gas chromatography and then identified by mass spectrographic analysis. Succinic dehydrogenase activity and radioactive labeling with tritiated leucine were used to evaluate cell metabolism and protein synthesis, respectively. The infrared analysis of the extracts showed that the primary component was unreacted BIS-GMA. Trace amounts of 2-hydroxy-4-methoxy-benzophenone, a light stabilizer, as well as a phenyl ester of benzoic acid which was probably degraded from BIS-GMA, were detected by the mass spectrographic method. The removal of leachable components caused a 90% decrease in toxicity compared to the nonextracted BIS-GMA samples. The extracted BIS-GMA samples showed no cellular response compared to the Teflon negative control.

Animals↗

PubMed2003

Fabrication of micropored elastomeric film-covered stents and acute-phase performances.

To prevent thrombus formation in the acute phase and restenosis in the subacute to chronic phase after stenting of atherosclerotic arteries, we developed a covered stent with a micropored elastomeric film, the blood-contacting surface of which was coated with a photocured gelatin layer immobilized with heparin. Segmented polyurethane (SPU) film (30 microm in wall thickness) as a cover material was multiply micropored by excimer laser-directed microprocessing (pore diameter, 30 microm; interpore distance, 125 microm). An aqueous mixed solution of benzophenone-derivatized gelatin and heparin was coated on the micropored SPU film. Upon ultraviolet light irradiation, a thin layer of a gelatin gel immobilized with heparin was formed and simultaneously fixed on the SPU film. The fully covered stents were assembled by wrapping a balloon-expandable stent with gelatin/heparin gel-layered SPU film and subsequently suturing and then gluing. To assess the validity of this covered stent in vivo, "half-covered" stents, in which half at the distal side was covered with the gel-layered SPU film, was implanted in rabbit common carotid arteries (about 3 mm in diameter). After 3 months of implantation, all the half-covered stents (n = 7) were patent. Regardless of the covered or noncovered region of the stents, the entire luminal surface of the stents was fully endothelialized and a thin neointimal tissue was formed. The potential advantages of a covered stent as designed above are discussed.

Animals↗

PubMed2003

Thermodynamics of solutions IV: Solvation of ketoprofen in comparison with other NSAIDs.

The present work discusses the characteristics of solvation (Gibbs energy, enthalpic and entropic terms of Gibbs energy) for ketoprofen together with other nonsteroidal antiinflammatory drugs (NSAIDs) in aliphatic alcohols. Ketoprofen was studied by classical thermoanalytical methods of sublimation calorimetry, solution calorimetry, and solubility. Temperature dependence of the saturated vapor pressure was determined, and the sublimation enthalpy, delta H(sub) (0) and sublimation entropy, delta S(sub)(0), as well as their respective relative fractions in the total process were calculated. The parameters yielded for ketoprofen were compared with the respective literature data of other benzophenone derivatives. The Gibbs energy of solvation as well as enthalpic and entropic terms thereof in aliphatic alcohols were also studied for ketoprofen and compared with the properties of model substances and other NSAIDs (benzoic acid, diflunisal, flurbiprofen, and naproxen). In all cases, the major driving force of the solvation process is enthalpy. Correlations were derived between Gibbs energy of solvation in octanol, delta G(solv)(oct), and the transfer Gibbs energy from water to octanol, delta G(tr)(0).

Alcohols↗

PubMed1975

GLC determination of plasma drug levels after oral administration of clorazepate potassium salts.

Plasma nordiazepam levels resulting from the oral administration of clorazepate potassium salts were determined by a sensitive GLC assay. Nordiazepam and the internal standard (diazepam) were selectively extracted into ether at pH 9.2, hydrolyzed to their respective benzophenones, and quantified by electron-capture detection. The assay was used in a comparative bioavailability study of single equimolar oral doses of monopotassium and dipotassium salts of clorazepate in dogs. Both clorazepate salts were rapidly absorbed and exhibited mean peak total drug levels after 1 hr. Clorazepate levels accounted for about 50% of the total drug levels present. No statistical difference in the plasma drug levels of clorazepate mono- and dipotassium salts and the metabolite was found in dogs.

Administration, Oral↗

PubMed1976

Kinetics and mechanisms of hydrolysis of 1,4-benzodiazepines I: chlordiazepoxide and demoxepam.

Differential absorbance spectroscopy was successfully used to follow the hydrolysis kinetics of chlordiazepoxide and demoxepam from pH 1 to 11. Loss of the methylamino group from chlordiazepoxide produced demoxepam. Demoxepam degraded by a parallel consecutive reaction to 2-amino-5-chlorobenzophenone and a glycine derivative. Two intermediates were observed by TLC for demoxepam hydrolysis. One was assigned the open-ring structure resulting from amide hydrolysis, which kinetically appears to be the major mechanistic route leading to the benzophenone product. The other intermediate, representing an alternative but minor pathway, presumably results from initial scission of the azomethine linkage. Protonation of the N-oxide slightly alters the importance of these two pathways. Recyclization of the carboxylic acid intermediate was facile at pH values below the pKa of this intermediate. The stability parameters involving buffer catalysis, ionic strength effects, and temperature dependence of rate constants are reported.

Benzodiazepines↗

PubMed1977

Kinetics and mechanisms of hydrolysis of 1,4-benzodiazepines II: oxazepam and diazepam.

The hydrolysis kinetics of oxazepam and diazepam leading to a benzophenone product and a glycine derivative were quantified from pH 1 to 11. For oxazepam, two intermediates were isolated and identified, indicating a parallel consecutive reaction mechanism. The hydrolysis occurred uncatalyzed and demonstrated acid-base catalysis for both reaction steps. One intermediate was observed by TLC for diazepam hydrolysis. This intermediate, resulting from breakage of the azomethine linkage, was different than the major intermediate isolated for oxazepam hydrolytic degradation (amide hydrolysis preferred). Stability parameters involving rate constant-temperature dependence are reported.

Chemical Phenomena↗

PubMed1978

Potential source of error in official diazepam assays.

A possible source of interference by a benzophenone hydrolysis product with the USP XIX spectrophotometric determination of diazepam in dosages forms is reported. A minor adaptation of the official assay procedures is briefly proposed as one method to correct this error.

Diazepam↗

PubMed1992

Gamma-pyrone compounds. II: Synthesis and antiplatelet effects of tetraoxygenated xanthones.

Norathyriol and its analogues, 1,3,5,6-, 3,4,5,6-, 3,4,6,7- and 2,3,6,7-tetrahydroxyxanthone, were synthesized from benzophenone precursors by Friedel-Crafts acylation and subsequent base-catalyzed cyclization to eliminate methanol. Both 3,4,6,7- and 2,3,6,7-tetrahydroxyxanthone tetraacetate showed potent anti-platelet aggregation effects on arachidonic acid-induced platelet aggregation. 3,4,6,7-Tetrahydroxyxanthone tetraacetate and 1,3,5,6-tetrahydroxyxanthone showed potent and significant anti-platelet aggregation effects on collagen-induced platelet aggregation.

Adenosine Diphosphate↗

PubMed1993

gamma-Pyrone compounds. IV: Synthesis and antiplatelet effects of mono- and dioxygenated xanthones and xanthonoxypropanolamine.

Xanthodilol, mono- and dioxygenated xanthones, and 1,3-, 2,3-, 3,4-, 3,5-, 1,6-, 2,6- and 3,6-dioxygenated xanthones were synthesized from benzophenone precursors by Friedel-Crafts acylation and subsequent base-catalyzed cyclization to eliminate methanol. 3-Hydroxy-xanthone, xanthodilol, 2,3-dihydroxyxanthone diacetate, and 3,4-dihydroxyxanthone and its diacetate showed potent antiplatelet effects on arachidonate- and collagen-induced aggregation. 3,5-Dihydroxyxanthone and its diacetate, 1,6-dimethoxyxanthone, and 3,6-dihydroxyxanthone and its diacetate showed potent antiplatelet effects on arachidonate-induced aggregation.

Adenosine Diphosphate↗

PubMed2004

Suppression of inducible nitric oxide synthase and cyclooxygenase-2 in downregulating nuclear factor-kappa B pathway by Garcinol.

Garcinol is a polyisoprenylated benzophenone derivative of Garcinia indica fruit rind and other species. Recent studies have demonstrated that garcinol exhibited antioxidative effects in vitro. In this study, we found that garcinol inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-activated macrophages. Western blot analyzes and gel-shift assays revealed that garcinol strongly blocks the activation of eukaryotic transcription factor nuclear factor-kappa B (NF-kappa B)-induced by LPS. Moreover, transient transfection experiments showed that garcinol inhibited the NF-kappa B-dependent transcriptional activity. Based on these data, we demonstrated that inhibition of LPS-induced NF-kappa B activation occurred through suppressing the phosphorylation of I kappa B alpha and p38 mitogen-activated kinase (MAPK). Garcinol also lowers the LPS-induced increase of intracellular reactive oxygen species (ROS), which contributes to the activation of NF-kappa B. The NF-kappa B signaling pathway leads to inflammatory reaction and our results suggest that garcinol suppresses the expression of iNOS in this pathway.

Animals↗