SEARCH · PubMed Health

Results for “Benzophenones”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources

PubMed2003

Characterization of peptide-protein interactions using photoaffinity labeling and LC/MS.

The combination of photoaffinity labeling (PAL) with modern mass spectrometric techniques is a powerful approach for the characterization of peptide-protein interactions. Depending on the analytical strategy applied, a PAL experiment can provide different levels of information ranging from the identification of interaction partners to the structural characterization of ligand-binding sites. On the basis of LC/MS data generated in the framework of the identification of the binding site of the neuropeptide corticotropin-releasing factor (CRF) on its binding protein (CRFBP), the key role of LC/MS in the characterization of photoadducts on different structural levels was demonstrated. Covalent photoadducts of rat CRFBP (rCRFBP) were obtained by PAL with different mono- and bifunctional benzophenone photoprobes designed on the basis of the sequence of the synthetic CRF fragment human/rat CRF(6-33) which binds to CRFBP with high affinity. In view of the stoichiometry, LC/MS analysis revealed that the photoadducts consisted of one molecule of photoprobe and one molecule of rCRFBP. For a further characterization of the photoadducts on the oligopeptide level, enzymatic digests of unlabeled rCRFBP and of the respective photoadduct were compared by peptide mapping monitored with LC/MS. Thereby, it was found that the photoprobe that contained the photophore at its N-terminus labeled the amino acid sequence rCRFBP(34-38), whereas the photoprobe that contained the photophore at its C-terminus labeled rCRFBP(12-26). On the basis of the characterization of the photoadduct formed by rCRFBP and the bifunctional photoprobe that contained photophores on both termini, semiquantitative comparison of different enzymatic digests was accomplished by application of the mass-selective multiple ion chromatogram strategy.

Amino Acid Sequence↗

PubMed2005

Quantification of urinary conjugates of bisphenol A, 2,5-dichlorophenol, and 2-hydroxy-4-methoxybenzophenone in humans by online solid phase extraction-high performance liquid chromatography-tandem mass spectrometry.

Urinary concentrations of phenols or their metabolites have been used as biomarkers to assess the prevalence of exposure to these compounds in the general population. Total urinary concentrations, which include both free and conjugated (glucuronide and sulfated) forms of the compounds, are usually reported. From a toxicologic standpoint, the relative concentrations of the free species compared with their conjugated analogs can be important because conjugation may reduce the potential biologic activity of the phenols. In this study, we determined the percentage of glucuronide and sulfate conjugates of three phenolic compounds, bisphenol A (BPA), 2,5-dichlorophenol (2,5-DCP), and 2-hydroxy-4-methoxybenzophenone (benzophenone-3, BP-3) in 30 urine samples collected between 2000 and 2004 from a demographically diverse group of anonymous adult volunteers. We used a sensitive on-line solid phase extraction-isotope dilution-high performance liquid chromatography-tandem mass spectrometry method. These three phenols were detected frequently in the urine samples tested. Only small percentages of the compounds (9.5% for BPA, and 3% for 2,5-DCP and BP-3) were excreted in their free form. The percentage of the sulfate conjugate was about twice that of the free compound. The glucuronide conjugate was the major metabolite, representing 69.5% (BPA), 89% (2,5-DCP), and 84.6% (BP-3) of the total amount excreted in urine. These results are in agreement with those reported before which suggested that BPA-glucuronide was an important BPA urinary metabolite in humans. To our knowledge, this is the first study describing the distribution of urinary conjugates of BP-3 and 2,5-DCP in humans.

Benzhydryl Compounds↗

PubMed2006

A validated method for the determination of traces of UV filters in fish using LC-MS/MS.

An analytical method for the determination of UV filter substances in fish tissue has been developed and validated using benzophenone-3, 3-(4-methylbenzylidene)-camphor, 2-ethylhexyl-2-cyano-3,3-diphenyl-2-propenoate and 2-ethylhexyl 3-(methoxyphenyl)-2-propenoate as target analytes. The fish fillets were homogenised and extracted by Soxhlet extraction. The extracts were run through a clean-up process including gel permeation chromatography followed by solid-phase extraction. Quantification of the compounds was performed using liquid chromatography with tandem mass spectrometric detection. Blank fish as well as spiked blank fish were analysed to validate the analytical method. The analytical method developed has the multiple advantages of enabling separation, simultaneous identification and quantification of each of the four selected compounds in a single run. Contamination of blank samples and abnormally high concentrations in spiked samples were avoided by taking extensive precautions during the fish preparation procedure. The method was validated in accordance with internationally accepted criteria, such as specificity, accuracy and repeatability. The combination of LC with tandem mass spectrometry ensures a high level of specificity. The accuracy of the method was reported as the mean recovery rate for the analytes in the sample matrix. Mean recoveries were in the range 86-108%. The precision is expressed as the relative standard deviation, and in all but one of the cases was 20% or below. The accuracy of the method allows residue analyses to be performed on biological matrices at ng/g levels. The determined limit of quantification for each analyte was 8 ng/g fish. For all spiking levels > or =8 ng/g, relative standard deviations were < or = 20%.

Acrylates↗

PubMed2006

Laser flash photolysis study on antioxidant properties of hydroxycinnamic acid derivatives.

The antioxidant properties of hydroxycinnamic acid derivatives (HCA) were studied by laser flash photolysis. The transient species with maximum absorption at 360 nm were assigned to the phenoxyl radical of HCA. The SO (4) (.-) induced oxidation of HCA was also investigated. It was shown that the interaction of SO (4) (.-) with HCA resulted in the formation of HCA phenoxyl radicals with rate constants of 2.0-3.9 x 10(9 )M(-1) s(-1). The reactions of HCA with triplet state of benzophenone were analyzed and quenching rate constants of 4.3-7.8 x 10(9 )M(-1) s(-1) were determined.

Absorption↗

PubMed1992

A rapid colorimetric assay for gamma-glutamyl hydrolase (conjugase).

A simple procedure for the measurement of gamma-glutamyl hydrolase (conjugase) activity is described. Glutamic acid released from pteroylpenta-gamma-glutamate by hog kidney and chicken pancreas conjugases was quantitated using the dye 4,4'-bis(dimethylamino)benzophenone hydrazone. The procedure involves hydrolysis of the folylpoly-gamma-glutamate substrate by conjugase, conversion of glutamate to alpha-ketoglutarate by L-glutamate dehydrogenase and colorimetric measurement of the BDBH derivative of alpha-ketoglutarate. The release of as little as one nmol of glutamic acid from the substrate can be measured by this procedure, which is well suited for the assay of a variety of conjugase preparations. In addition, the method should provide a general assay for the enzymatic hydrolysis of various folate and antifolate polyglutamates.

Animals↗

PubMed1991

Formation and properties of smooth muscle myosin 20-kDa light chain-skeletal muscle myosin hybrids and photocrosslinking from the maleimidylbenzophenone-labeled light chain to the heavy chain.

Experimental conditions which permit the exchange of smooth muscle 20-kDa light chain into skeletal muscle myosin are described. The hybridization does not result in the regulation of actin-activated ATPase activity of the hybrid myosin by smooth light chain phosphorylation. Further, the KCl dependence of the Mg-ATPase activity of the hybrid was similar to that of skeletal muscle myosin. The dephosphorylation of the smooth light chain in the hybrid did not induce a conformational change in the hybrid from the 6 S to the 10 S state, thereby indicating that the conformational transition is dependent also on the nature of the heavy chain subunit. Exchange of the smooth light chain premodified at its Cys-108 by photolabile 4-(N-maleimido)benzophenone and photolysis resulted in crosslinking to the heavy chain subunit. Immunopeptide mapping using a monoclonal antibody against residues 1-23 at the N-terminus of the skeletal muscle myosin heavy chain identified the location of the photocrosslinking site to be beyond 92 kDa away from the N-terminus.

Actins↗

PubMed1988

Photoaffinity labelling of a 150 kDa (Na + K + Cl)-cotransport protein from duck red cells with an analog of bumetanide.

We have used a radiolabelled, benzophenone analog of bumetanide, 4-[3H]benzoyl-5-sulfamoyl-3-(3-thenyloxy)benzoic acid ([3H]BSTBA) to photolabel plasma membranes from duck red blood cells. BSTBA, like bumetanide, is a loop diuretic and a potent inhibitor of (Na + K + Cl) cotransport, and [3H]BSTBA binds to intact duck red cells with a high affinity similar to that of [3H]bumetanide (K 1/2 congruent to 0.1 microM). We incubated duck red cells with [3H]BSTBA, then lysed the cells and exposed the ghosts to ultraviolet light. The ghosting and photolysis was done at 0 degree C to prevent dissociation of the [3H]BSTBA. The ghosts were then sonicated to remove the nuclei and run on SDS-polyacrylamide gels. Analysis of H2O2-digested gel slices revealed [3H]BSTBA to be incorporated into a protein of approx. 150 kDa. This is the same molecular weight we obtain for a protein from dog kidney membranes which is photolabelled by [3H]BSTBA in a manner highly consistent with labelling of the (Na + K + Cl) cotransporter (Haas and Forbush (1987) Am. J. Physiol. 253, C243-C252). Several lines of evidence strongly suggest that the 150 kDa protein from duck red cell membranes is an integral component of the (Na + K + Cl)-cotransport system in these cells: (1) Photolabelling of this protein by [3H]BSTBA is blocked when 10 microM unlabelled bumetanide is included in the initial incubation medium with [3H]BSTBA; (2) Photoincorporation of [3H]BSTBA into the 150 kDa protein is markedly increased when the initial incubation medium is hypertonic or contains norepinephrine, conditions which similarly stimulate both (Na + K + Cl) cotransport and saturable [3H]bumetanide binding in duck red cells; (3) The photolabelling of this protein shows a saturable dependence on [3H]BSTBA concentration, with a K1/2 (0.06 microM) similar to that for the reversible, saturable binding of [3H]BSTBA and [3H]bumetanide to duck red cells; and (4) [3H]BSTBA photoincorporation into the 150 kDa protein, like saturable [3H]bumetanide binding to intact cells, requires the simultaneous presence of Na+, K+, and Cl- in the medium containing the radiolabelled diuretic.

Affinity Labels↗

PubMed1987

Induction of peroxisomal fatty acyl-CoA oxidase and microsomal laurate hydroxylase activities by beclobric acid and two metabolites in primary cultures of rat hepatocytes.

Beclobrate [2-(4-[(4-chlorophenyl)methyl]phenoxy)-2-methylbutyric acid ethyl ester], a structural analog of clofibrate, is used clinically as a lipid-lowering agent. Although, like clofibrate, beclobrate produces a profound hepatomegalic response in rodents, no studies of this drug on hepatic peroxisome proliferation have appeared. We have examined, relative to clofibric acid (CPIB), the concentration-dependent effects of beclobric acid (Beclo), the activity moiety of beclobrate, and two oxidized metabolites [a carbinol (M2) and a benzophenone (M3)] on peroxisomal fatty acyl-CoA oxidase (FACO) and microsomal laurate hydroxylase (LH) activities in primary cultures of rat hepatocytes. All compounds induced FACO and LH activities in a concentration-dependent manner after a 72 hr incubation with the cultured cells. Beclo was 4.8- and 6.5-fold more potent than CPIB as an inducer of FACO and LH respectively. M2 and M3 were more potent than Beclo as inducers of FACO and LH. Additionally, all compounds produced significant elevations relative to untreated control cultures in cellular lactate dehydrogenase activity (1.6- to 2.2-fold). We conclude that (1) Beclo is more potent than CPIB as an inducer of peroxisome proliferation-associated enzyme activities; (2) two metabolites of Beclo are more potent than the parent molecule as inducers of these activities and (3) these metabolites may contribute to the lipid-lowering and/or hepatomegalic effects of beclobrate in rats.

Acyl-CoA Oxidase↗

PubMed1992

The amino-terminal fragment of gelsolin is cross-linked to Cys-374 of actin in the EGTA-resistant actin-gelsolin complex.

It has been shown that the EGTA-resistant actin, one of the two actin molecules associated to gelsolin, can be predominantly cross-linked to gelsolin by benzophenone-4-maleimide (BPM), a photoaffinity-labeling reagent, which was conjugated to Cys-374 of actin prior to cross-linking (Doi, Y., Banba, M. and Vertut-Doï, A. (1991) Biochemistry 30, 5769-5777). When a chymotryptic digest of gelsolin containing the amino-terminal 15-kDa fragment was mixed with BPM-actin (42 kDa) and irradiated for cross-linking, a band of 58 kDa appeared on SDS-PAGE which was shown to contain actin molecule by using fluorescently labeled actin. The amino-terminal sequence of the 58-kDa complex was identical to that of gelsolin, confirming that the amino-terminal segment (residues 1-133) of pig plasma gelsolin lies closely to Cys-374 of actin in the EGTA-resistant complex.

Actins↗

PubMed1983

Specific interaction of some non-steroidal compounds with the progesterone binding site of uteroglobin.

Uteroglobin binds progesterone with high affinity. A few substituted diphenyl ketones were observed to inhibit uteroglobin-progesterone binding in a dose-dependent manner. 4,4'-Dimethoxy-2-hydroxy benzophenone had relatively higher affinity for uteroglobin. The structure-activity relationship amongst the substituted diphenyl ketones indicated considerable sensitivity towards minor structural modifications. These observations offer a tool to investigate nonsteroidal compounds in relation to progesterone related functions of uteroglobin in pregnancy.

Animals↗

PubMed1987

The effects of exifone, a new agent for senile memory disorder, on two models of memory in the mouse.

The effects of exifone (ADLONE), hexahydro-2,3,4,3',4',5'-benzophenone, were tested in two models of memory in the mouse: habituation of exploratory activity and antagonism of amnesia induced by scopolamine in a passive avoidance task. In the first model, mice which had received exifone (128 and 256 mg/kg IP) 30 minutes before a 3 minute exposure to a staircase exploratory test showed a more marked decrease in exploratory activity in the same apparatus 24 hours later (habituation) than a control group indicating improved memory. Similar results were obtained with piracetam (512 mg/kg, IP). In the second model exifone (512 mg/kg PO), administered 60 minutes before both the learning and retention trials of a standard step-through passive avoidance, task partially antagonized the amnesia induced by 10 mg/kg scopolamine IP administered immediately after the learning trial. Similar results were obtained with piracetam (800 mg/kg PO). Taken together these results suggest that exifone facilitates memory function in simple rodent models in a manner consistent with its supposed therapeutic effects in man.

Amnesia↗

PubMed1988

Testing of the abiotic degradation of chemicals in the atmosphere: the smog chamber approach.

Methods for measuring the hydroxyl-, ozone-, and direct photochemical reactivity of a substance in one specially designed medium size smog chamber are described. Rate coefficients for the reaction of OH with n-hexane, n-heptane, ethene, ethyne, chloroform, trichloroethene, methanol, 2-propanol, benzene, o-xylene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene, p-chloroaniline, naphthalene, acenaphthene, 1,4-dichloronaphthalene, biphenyl, and fluorenone are given and discussed. An upper limit of 5 X 10(-13) cm3/sec is given for the sum penta- and hexa-chlorobiphenyls (PCB). Rate coefficients for the ozone reaction are given for beta-pinene, limonene, delta 3-carene, cineol, vinyl chloride and 1,3-butadiene. In cases where the literature data are available for comparison, the rate coefficients (kappa OH and kappa O3) reported here compare favorably with the best data reported. The direct photochemical reactivity has been shown to be measurable if the chamber is cleaned carefully. Preliminary results on benzophenone are reported. The methods described here, except that of direct photochemical reactivity, are in agreement with those proposed to OECD. Moreover, part of the Draft OECD Test Guideline (Berlin, 1987) on "Photochemical-Oxidative Degradation in the Atmosphere" is based on work described here and on closely related work in other laboratories (Becker et al., 1984).

Benzophenones↗

PubMed1983

A comparison of the mutagenicity and macromolecular binding of the carcinogens Michler's ketone and reduced Michler's ketone.

The mutagenicity of 4,4'-bis(dimethylamino)benzophenone (Michler's ketone, MK, CAS No. 90-94-8) and 4,4'-methylenebis(N,N-dimethyl)benzamine (reduced Michler's ketone, RMK, CAS No. 101-61-1) for Salmonella typhimurium strain TA100 was compared using activated 9000 X g (S9) liver supernatants from 2 animal species. RMK, but not MK, was mutagenic when incubated with phenobarbital-induced B6D2F1 mouse or Osborne-Mendel rat-liver S9. The mutagenic response for RMK was linear at doses from 1 to 33 micrograms/plate. A higher percentage of RMK and MK became irreversibly bound to mouse-liver macromolecules than to rat-liver macromolecules when incubated at 37 degrees C in the presence of reduced nicotinamide adenine dinucleotide phosphate.

Aniline Compounds↗

PubMed1987

CGP 11.952: an experimental benzodiazepine derivative. Effects on cognitive functioning in patients with epilepsy.

1. In two open studies using patients with intractable epilepsy, the effects of CGP 11.952, a triazolyl benzophenone, on cognitive functioning were assessed by means of a computerized neuropsychological battery. 2. In the first study CGP 11.952 turned out to have a positive effect on information processing speed, perceptual sensitivity and preciseness of responses. 3. Negative effects were found on reaction time. 4. In the second study this latter effect was less clear. 5. A striking result was the less negative effect on memory consolidation under influence of CGP 11.952 in comparison with other benzodiazepines.

Adolescent↗

PubMed1992

Analysis of photoacoustic waveforms using the nonlinear least squares method.

Pulsed-laser photoacoustics is a technique which measures photoinduced enthalpic and volumetric changes on the nano- and microsecond timescales. Analysis of photoacoustic data generally requires deconvolution for a sum of exponentials, a procedure which has been developed extensively in the field of time-resolved fluorescence decay. Initial efforts to adapt an iterative nonlinear least squares computer program, utilizing the Marquardt algorithm, from the fluorescence field to photoacoustics indicated that significant modifications were needed. The major problem arises from the wide range of transient decay times which must be addressed by the photoacoustic technique. We describe an alternative approach to numerical convolution with exponential decays, developed to overcome the problems. Instead of using an approximation method (Simpson's rule) for evaluating the convolution integral, we construct a continuous instrumental response function by quadratic fitting of the discrete data and evaluate the convolution integral directly, without approximations. The success and limitations of this quadratic-fit convolution program are then demonstrated using simulated data. Finally, the program is applied to the analysis of experimental data to compare the resolution capabilities of two commercially available transducers. The advantages of a broadband, heavily damped transducer are shown for a standard organic photochemical system, the quenching of the triplet state of benzophenone by 2,5-dimethyl-2,4-hexadiene.

Algorithms↗

PubMed1990

Dioxygenolytic cleavage of aryl ether bonds: 1,2-dihydro-1,2-dihydroxy-4-carboxybenzophenone as evidence for initial 1,2-dioxygenation in 3- and 4-carboxy biphenyl ether degradation.

A bacterial strain, Pseudomonas sp. POB 310, was enriched with 4-carboxy biphenyl ether as sole source of carbon and energy. Resting cells of POB 310 co-oxidize a substrate analogue, 4-carboxybenzophenone, yielding 1,2-dihydro-1,2-dihydroxy-4-carboxy-benzophenone. The ether bond of 3- and 4-carboxy biphenyl ether is cleaved analogously by initial 1,2-dioxygenation, yielding a hemiacetal which is hydrolysed to protocatechuate and phenol. These intermediates are degraded via an ortho and meta pathway, respectively. Alternative 2,3- and 3,4-dioxygenation can be ruled out as triggering steps in carboxy biphenyl ether degradation.

Benzoates↗

PubMed1995

Interaction of melanin with carbon- and oxygen-centered radicals from methanol and ethanol.

The interaction of dopa-melanin (DM) and cysteinyldopa-melanin (CDM) with carbon- and oxygen-centered radicals generated by benzophenone-photosensitized hydrogen abstraction from ethanol, or by pulse radiolysis of aqueous solutions of methanol and ethanol, is reported. Photosensitized formation of carbon-centered radicals and their interaction with melanin was monitored by electron paramagnetic resonance (EPR) spin trapping using DMPO, and via the melanin free radical signal itself. In the pulse radiolysis experiments, the interaction of DM or CDM with hydroxymethyl, hydroxyethyl, and the corresponding methanol peroxyl radical was monitored by recording time-dependent changes of the melanin absorbance at selected wavelengths. The data indicate that both melanins are good scavengers of carbon-centered radicals, with corresponding rate constants in the range of 10(7) to 10(8) M-1 s-1. Significantly, compared to DM, CDM is also an exceptionally efficient scavenger of oxygen-centered radicals derived from methanol with corresponding rate constants of 2.7 x 10(4) and 2 x 10(6) M-1 s-1 for DM and CDM, respectively. The results are discussed with reference to the potential role of melanin in protecting the integrity of melanosomes by inhibiting peroxidation of lipid components of the organelle membrane.

Benzophenones↗

PubMed2005

The effect of camphorquinone (CQ) and CQ-related photosensitizers on the generation of reactive oxygen species and the production of oxidative DNA damage.

Recent evidence suggests that following visible-light (VL) irradiation, CQ and the CQ-related photosensitizers benzil (BZ), benzophenone (BP), and 9-fluorenone (9-F) generate initiating radicals that may indiscriminately react with molecular oxygen forming reactive oxygen species (ROS). The purpose of this investigation was to determine whether VL-irradiated CQ, BZ, BP, and 9-F cause DNA damage due to the generation of ROS in vitro. ROS formation by CQ and CQ-related photosensitizers+/-dimethyl-p-toluidine (DMT) was investigated in a cell-free system with VL irradiation. DNA damage was determined using PhiX-174 RF I supercoiled double-stranded plasmid DNA and ROS quantified with 4-((9-acridinecarbonyl)amino)-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO-9-AC), a fluorogenic ROS-sensitive probe. VL-irradiated CQ, BZ, BP, and 9-F (+/-DMT) produced significant DNA damage at 0.1, 0.5, and 1.0 mM and in a concentration-dependent manner (p<0.05). TEMPO-9-AC revealed that all investigated VL-irradiated photosensitizers produced significant amounts of ROS with BZ in the presence of DMT generating the most ROS after 30, 60, and 90 min. VL-irradiated CQ, BZ, BP, and 9-F +/-DMT continued to generate significant amounts of ROS 90 min after VL irradiation. As a result, future investigations should evaluate the effect of VL-irradiated photosensitizers in cells and possible protective effects provided by antioxidants.

Benzophenones↗