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PubMed2005

Anti-tumor and proapoptotic effect of novel synthetic benzophenone analogues in Ehrlich ascites tumor cells.

A series of substituted benzophenone analogues, (2-aroyl-4-methylphenoxy)acetamides 4a-e, have been synthesized via three-step synthesis sequence beginning with the 2-hydroxybenzophenones 1a-e in excellent yield. 1a-e on reaction with ethyl chloroacetate afford ethyl (2-aroyl-4-methylphenoxy)acetates 2a-e which on alkaline hydrolysis afforded (2-aroyl-4-methylphenoxy)ethanoic acid 3a-e. Compounds 3a-e on condensation with p-chloroaniline furnished benzophenone analogues 4a-e. In the present report, we investigated the anti-tumor and proapoptotic effect of benzophenones in Ehrlich ascites tumor (EAT) cells. Treatment of benzophenones in vivo resulted in inhibition of proliferation of EAT cells and ascites formation. Further, we demonstrate that the induction of apoptosis in EAT cells is mediated through activation of caspase-3. These results suggest a further possible clinical application of these synthetic compounds as potent anti-tumor and proapoptotic compounds.

Animals↗

PubMed2003

Determination of benzophenones in a cosmetic matrix by supercritical fluid extraction and capillary electrophoresis.

Benzophenones are common additives in commercial sunscreen products. These UV absorbers were extracted by supercritical fluid extraction (SFE), and then analyzed by capillary zone electrophoresis (CZE) and high-performance liquid chromatography. This study was applied to identify the contents of benzophenones in cosmetic matrix, and simultaneously, to investigate the behavior of migration in CZE. Adding non-ionic surfactant (Tween 20) to optimize the separation in the CZE operation improves resolution. In SFE, we chose carbon dioxide with 2.5% modifier of 10% aqueous phosphoric acid-MeOH (1:1) as the supercritical fluid. Real recoveries of up to 92% with relative standard deviations of less than 4.0% were achieved. These analytical techniques were also applied to assay benzophenones for ten commercial sunscreen cosmetics. We found benzophenone 3 was the most commonly used sunscreen additive in Taiwan.

Benzophenones↗

PubMed2002

Modulation of GABA(A) receptor-mediated currents by benzophenone derivatives in isolated rat Purkinje neurones.

We investigated modulation of GABA(A) receptor-mediated whole-cell currents in cerebellar Purkinje neurones by several derivatives of benzophenone. A metabolite of phenazepam, 5-bromo-2'-chloro-2-aminobenzophenone (I), caused dual modification of peak amplitudes of GABA-gated currents that depended upon the concentration of applied GABA and incubation time. Following short 10 s pre-incubations, 1-30 microM I facilitated activation and delayed deactivation of currents evoked by 500 ms pulses of 20 microM GABA. In addition, 10 microM I prominently enhanced desensitisation of currents during applications of 500 microM GABA mainly by decreasing the value of the fast time constant of the desensitisation. Continuous 6 min incubation with 10 microM I during GABA stimulation or its administration between but not during 1 s pulses of 500 microM GABA led to a gradual, partly reversible attenuation of GABA-activated currents. This inhibition was not observed when I was applied only during pulses of GABA, indicating that the blockade was not use-dependent. One of the possible mechanisms of this down-modulation could be an intracellular effect of I, because when applied intracellularly it caused slow inhibition of responses to consecutive GABA pulses. When 3-30 microM I was applied on the background of small 'plateau'-like current 5-7 s after application of 500 microM GABA, it was able to block open channels with on and off rates similar to those observed with 30 microM picrotoxin but much slower than in the case of 500 microM benzylpenicillin. At a concentration of 10 microM, 5-substituted benzophenones, but not 2-aminobenzophenone or benzophenone itself, exhibited modulatory properties similar to I and distinct from those of picrotoxin and benzylpenicillin. Therefore, we conclude that derivatives of benzophenone are a novel class of GABA(A) receptor modulators with a unique pharmacological profile.

Animals↗

PubMed2000

Benzophenones of Garcinia pseudoguttifera (Clusiaceae).

Four biogenetically related benzophenones have been isolated from the Fijian Garcinia pseudoguttifera. They are: 6-hydroxy-2,4-dimethoxy-3,5-bis(3-methyl-2-butenyl)benzophenone (myrtiaphenone-A); 2,2-dimethyl-8-benzoyl-7-hydroxy-5-methoxy-6-(3-methyl-2-butenyl)benzopy ran (myrtiaphenone-B); 2,6-dihydroxy-4-methoxy-3,5-bis(3-methyl-2-butenyl)benzophenone (vismiaphenone-C) and a new benzophenone, 2,2-dimethyl-8-benzoyl-3,7-dihydroxy-5-methoxy- 6-(3-methyl-2-butenyl)-3,4-dihydrobenzopyran (pseudoguttiaphenone-A). Pseudoguttiaphenone-A could be biogenetically derived from vismiaphenone-C. The major component of G. pseudoguttifera was identified as eupha-8,24-dien-3 beta-ol.

Benzophenones↗

PubMed1991

Further studies on ultraviolet-absorbing hydrogels for intraocular lenses: relationship between concentration of a polymerizable benzophenone, absorption, and extractability.

A tendency to reduce the use of benzophenone absorbers is currently evident in the manufacture of the UV-absorbing IOLs, mainly because the cutoff wavelengths are inferior to those provided by benzotriazoles. In principle, by incorporating large amounts of benzophenones it may be possible to achieve high cutoff wavelengths. A covalently bondable benzophenone UV absorber, Cyasorb UV-2098, was incorporated in poly(2-hydroxyethyl methacrylate) (PHEMA) in increasing concentrations, and certain associated phenomena were investigated. At 4% w/w absorber content, the nonhydrated polymers turned partially opaque. In water-swollen hydrogels, opacification occurred at a lower absorber content (2% w/w). By using extraction techniques and gas chromatography, we also found that up to 8% w/w of the absorber remained unpolymerized and could leach out from any material containing less than 5% w/w absorber. In samples with higher initial content of absorber, the amount of unreacted, leachable absorber was significantly higher (25% to 30%). Based on this study model (hydrogel/Cyasorb UV-2098), we concluded that benzophenone absorbers cannot provide cutoff wavelengths higher than those provided by benzotriazoles.

Acrylates↗

PubMedDate not supplied

Sulfhydryl-reactive, cleavable, and radioiodinatable benzophenone photoprobes for study of protein-protein interaction.

The major task in proteomics is to understand how proteins interact with their partners. The photo-cross-linking technique enables direct probing of protein-protein interaction. Here we report the development of three novel sulfhydryl-reactive benzophenone photoprobes of short "arm" length, each with a substitution of either amino, iodo, or nitro at the para-position, rendering the benzophenone moiety directly radioiodinatable. Their potential for study of protein-protein interaction was assessed using the inhibitory subunit of rod cGMP phosphodiesterase (PDEgamma) and the activated transducin alphasubunit (G alpha t-GTPgammaS) as a model system. These photoprobes proved to be stable at neutral pH and dithiothreitol-cleavable in addition. The PDEgamma constructs derivatized at the C-terminal positions with these probes could be readily purified, had unaltered PDEgamma functional activity, and were shown to photo-cross-link to G alpha t-GTPgammaS with an efficiency as high as 40%. Additionally, the amino benzophenone probe was radioiodinated, facilitating sensitive detection of label transfer. The uniquely combined features of these benzophenone photoprobes promise robust and flexible methods for characterization of protein-protein interaction, either by mass spectrometry when a nonradioactive label is available or by autoradiography when using radioiodinated derivatives.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1995

Benzophenone derivatives: a novel series of potent and selective inhibitors of human immunodeficiency virus type 1 reverse transcriptase.

A series of benzophenone derivatives has been synthesized and evaluated as inhibitors of HIV-1 reverse transcriptase (RT) and the growth of HIV-1 in MT-4 cells. Through the use of the structure-activity relationships within this series of compounds and computational chemistry techniques, a binding conformation is proposed. The SAR also indicated that the major interactions of 1h with the RT enzyme are through hydrogen bonding of the amide and benzophenone carbonyls and pi-orbital interactions with the benzophenone nucleus and an aromatic function separated from the benzophenone by a suitable spacer group. The crystal structure of compound 1h has been determined. A number of compounds with potent inhibitory activity against HIV-1 RT and HIV in cellular assays at levels comparable with AZT and our efforts to identify a metabolically stable analogue are described.

Benzophenones↗

PubMed2007

Synthesis and properties of benzophenone-spiropyran and naphthalene-spiropyran conjugates.

We have designed and synthesized four compounds integrating luminescent and photochromic components in their molecular skeletons. Two of them combine a nitrospiropyran photochrome with either one or two naphthalene fluorophores and can be prepared in three synthetic steps. The other two consist of a nitrospiropyran photochrome and a benzophenone phosphore connected by either ether or ester linkages and can be prepared in six or five, respectively, synthetic steps. The luminescent components of these assemblies are expected to transfer energy intramolecularly to the photochromic species upon excitation and encourage their photoisomerization. Consistently, the phosphorescence of the benzophenone units and the fluorescence of the naphthalene components are effectively quenched when these species are connected covalently to a nitrospiropyran. Nonetheless, the photoisomerization of the photochrome becomes significantly less efficient after the covalent attachment to the luminescent partner. The fraction of incident radiations absorbed by either the benzophenone or the naphthalene fragment does not promote the isomerization of the photochromic appendage. Instead, irreversible transformations occur upon irradiation of the luminophore-photochrome assemblies. Thus, the covalent attachment of a benzophenone or a naphthalene to a nitrospiropyran is not a viable strategy to improve the photocoloration efficiency of the photochromic component. Even although the very same luminophores are known to sensitize intermolecularly the isomerization of nitrospiropyrans, the transition to covalent luminophore-photochrome assemblies tends to promote degradation, rather than sensitization, upon irradiation.

Benzophenones↗

PubMed1993

Benzophenone-sensitized lipid peroxidation in linoleate micelles.

Benzophenone-photosensitized peroxidation in linoleic acid micelles (Type I reaction) has been investigated and quantum yields of both sensitizer photolysis and lipid peroxidation have been obtained. Benzophenone as well as its derivative, benzophenone-4'-heptyl-4-pentanoic acid (BHPA) have been utilized as sensitizers in this study. A quantum yield of 1.2 for hydroperoxide formation, compared with a benzophenone disappearance quantum yield of 0.41 (in the same linoleate micellar solution) was obtained; yields of 1.3 and 0.6 were found for comparable systems in which BHPA was the sensitizer. Although such data are consistent with the peroxidation mechanism of chain reaction, it is necessary to know the yields of initiating species to arrive at chain reaction lengths in these systems. Such yields have been determined by flash photolysis. The dependencies of sensitizer photolysis and hydroperoxide yields on linoleate concentration have also been determined in order to elucidate the effects of micelle formation or molecular organization on the peroxidative process. Additionally, for comparison in a saturated surfactant (lipid) system hydrogen abstraction was investigated by photolysis techniques in sodium dodecyl sulfate alone using these two sensitizers.

Benzophenones↗

PubMed2000

Iron-mediated synthetic routes to unsymmetrically substituted, sterically congested benzophenones

A new synthetic route to unsymmetrically substituted benzophenones, relying upon iron-mediated reactions in all of the key steps, is described. The key buiding block, eta6-2-chloro-carbomethoxybenzene-eta5-cyclopentadienyl iron hexafluorophosphate (4), is reacted with a variety of substituted phenols, providing diaryl ether complexes (6). After hydrolysis of the ester functionalities, these complexes are subjected to Friedel-Crafts conditions. The efficiency of this intramolecular acylation reaction is very much dependent upon the substituents on the phenols. If these are appropriately chosen, xanthone complexes are isolated in fair to good yields. Regioselective ring-opening, using oxygen-nucleophiles, delivers substituted benzophenone complexes. After regioselective nucleophilic addition of cyanide ion, performed in the presence of DDQ, highly substituted benzophenones are isolated. To demonstrate the applicability of the new route, a formal synthesis of the benzophenone moiety of the protein kinase C inhibitor Balanol (3) is described.

Journal Article↗

PubMed1997

Stereoselective Synthesis of 4'-Benzophenone-Substituted Nucleoside Analogs: Photoactive Models for Ribonucleotide Reductases.

Ribonucleotide reductases (RNRs) catalyze the 2'-reduction of ribonucleotides, thus providing 2'-deoxyribonucleotides, the monomers for DNA biosynthesis. The current mechanistic hypothesis for the catalysis effected by this class of enzymes involves a sequence of radical reactions. A reversible 3'-hydrogen abstraction, effected by a radical at the enzyme's active site, is believed to initiate the catalytic cycle. For the study of this substrate-enzyme interaction, a series of 4'-benzophenone-substituted model compounds was designed and synthesized. In these models, the benzophenone carbonyl group is oriented such that irradiation is expected to result in an enzyme-like, reversible 3'-hydrogen abstraction. The key step of our synthetic approach is the highly diastereoselective (dr > 95:5) Grignard-addition of carbonyl-protected o-benzophenone magnesium bromide to 2,3-O-isopropylidene-beta-L-erythrofuranose. The configuration of the newly established chiral center was unambiguously proven by X-ray crystallography. The erythritol derivative thus obtained was dehydrated to a base-free, 4'-benzophenone-substituted nucleoside analog. This first model system was further modified by transforming the free 2',3'-hydroxyl groups into the mono- and bis-methyl ethers, into the cyclic carbonate, and into the mono- and bis-mesylates. Alternatively, the primary hydroxyl group of the erythritol intermediate was selectively oxidized to the aldehyde. In the furanose thus obtained, the stage is set for the additional introduction of a nucleobase at the 1'-position.

Journal Article↗

PubMed1994

Photochemical and photobiological properties of ketoprofen associated with the benzophenone chromophore.

Irradiation of ketoprofen in neutral aqueous medium gave rise to 3-ethylbenzophenone as the major photoproduct. Its formation is justified via protonation of a benzylic carbanion or hydrogen abstraction by a benzylic radical. Minor amounts of eight additional compounds were isolated. Four of them are derived from the benzylic radical: 3-(1-hydroperoxyethyl)benzophenone, 3-(1-hydroxyethyl)benzophenone, 3-acetylbenzophenone and 2,3-bis-(3-benzoylphenyl)butane. The other four products involve initial hydrogen abstraction by the excited benzophenone chromophore of ketoprofen: 1,2-bis-(3-ethylphenyl)-1,2-diphenyl-1,2-ethanediol, 2-(3-benzoylphenyl)-1-(3-ethylphenyl)-1-phenylpropan-1-ol, alpha-(3-ethylphenyl)phenylmethanol, 1,2-bis-[3-(2-hydroxycarbonylethyl) phenyl]-1,2-diphenyl-1,2-ethanediol. The latter process was found to mediate the photoperoxidation of linoleic acid through a type I mechanism, as evidenced by the inhibition produced by the radical scavengers butylated hydroxyanisole and reduced glutathione. The major photoproduct, which contains the benzophenone moiety but lacks the propionic acid side chain, also photosensitized linoleic acid peroxidation. Because lipid peroxidation is indicative of cell membrane lysis, the above findings are highly relevant to explain the photobiological properties of ketoprofen.

Dermatitis, Phototoxic↗

PubMed2005

Intramolecular interactions in the triplet excited states of benzophenone-thymine dyads.

Time-resolved and product studies on the synthesized dyads 1 and 2 have provided evidence that the benzophenone-to-thymine orientation strongly influences intramolecular photophysical and photochemical processes. The prevailing reaction mechanism has been established as a Paterno-Büchi cycloaddition to give oxetanes 3-6; however, the ability of benzophenone to achieve a formal hydrogen abstraction from the methyl group of thymidine has also been evidenced by the formation of photoproducts 7 and 8. These processes have been observed only in the case of the cisoid dyad 1. Adiabatic photochemical cycloreversion of the oxetane ring is achieved upon direct photolysis to give the starting dyad 1 in its excited triplet state. The photobiological implications of the above results are discussed with respect to benzophenone-photosensitized damage of thymidine.

Benzophenones↗

PubMed2005

Analyses of benzophenones by capillary electrochromatography using methacrylate ester-based monolithic columns.

In this study, eight benzophenones, which are commonly used as UV filters in various cosmetics and plastics, were analyzed by capillary electrochromatography with a methacrylate ester-based monolithic column. The effects of the composition and pH of mobile phase, porogenic solvent ratio, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) content on benzophenone separations were examined. For all benzophenones, separation performances were markedly improved in monolithic columns with larger 1-propanol ratio and higher AMPS content. Furthermore, a twofold increase in AMPS content almost reduced the separation time in half when a monolithic column had an adequately high surface area, i.e. monolithic column was produced in a higher ratio of 1-propanol. As well, the retention behaviors of these analytes in the monolithic column were strongly influenced by the level of acetonitrile in the mobile phase, and the pH of the mobile phase also had an apparent influence on separation resolution.

Benzophenones↗

PubMed2002

Two benzophenone O-arabinosides and a chromone from Hypericum annulatum.

Two benzophenone O-arabinosides, annulatophenonoside (1) and acetylannulatophenonoside (2) were isolated from the methanol extract of the herb of Hypericum annulatum. The structures of the benzophenones were established as 2-O-alpha-L-arabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone (1) and 2-O-alpha-L-3"-acetylarabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone (2) based on spectral and chemical evidence. A chromone, 5,7-dihydroxy-3-methylchromone (3) was isolated from the chloroform extract. Although it has been previously synthesized it is encountered in a plant source for the first time. Co-occurrence of the two new benzophenone O-arabinosides along with the biogenetically related 1,5,7-trihydroxy-3-methoxyxanthone was not found.

Benzophenones↗

PubMed2002

Polarographic determination of phenytoin and benzophenone (as impurity) in pharmaceutical preparations.

A differential pulse polarographic method is described for detection and trace determination of benzophenone (the main impurity) in phenytoin powder. The method depends upon the polarographic activity of benzophenone in Britton-Robinson buffer pH 5.6. The limit of detection was found to be 2.5 x 10(-6) microg ml(-1). Phenytoin has been analysed polarographically after oxidation with alkaline permanganate to give benzophenone; the limit of detection was found to be 6 x 10(-6) microg ml(-1).

Benzophenones↗

PubMed2002

4,4'-Benzophenone-O,O'-disulfamate: a potent inhibitor of steroid sulfatase.

We investigated whether the benzophenone moiety can be used as core element of steroid sulfatase (STS) inhibitors. While 4- and 3-benzophenone-O-sulfamates inhibit STS with IC(50) values between 5 and 7 microM irrespective of additional hydroxy and methoxy substituents at the second phenyl ring, benzophenone-O,O'-disulfamates show increased activity. With an IC(50) value of 190 nM the 4,4'-derivative is the first small monocyclic STS inhibitor coming close to the potency of the steroidal standard estrone sulfamate.

Arylsulfatases↗

PubMed2001

Slow photo-cross-linking kinetics of benzophenone-labeled voltage sensors of ion channels.

Voltage-gated ion channels have voltage sensors that move in response to changes in membrane potential. This movement regulates the gates that control access of ions to the permeation pathway. To study the coupling between voltage sensors and gates, we immobilize the voltage sensors, using a bifunctional photo-cross-linking reagent that can be attached to an introduced cysteine, and observe the consequences for gate movement [Horn, R., Ding, S., and Gruber, H. J. (2000) J. Gen. Physiol. 116, 461-475]. UV irradiation of the benzophenone adduct attached to the cysteine residue immobilizes the voltage sensors, S4 segments, of both Na(+) and Shaker K(+) channels. Here we examine the kinetics of S4 immobilization after a brief UV flash. Immobilization has an exponential time course with time constants of >200 ms for Shaker and 17 ms for Na(+) channels, whereas the triplet excited state lifetime of the benzophenone adduct is <1 ms. This result suggests that H-atom abstraction by benzophenone is rapid and that the rate-limiting step in immobilization is the recombination of alkyl and ketyl free radicals generated by H-abstraction. H-Abstraction is also 2.7-fold more efficient at a hyperpolarized voltage than at a depolarized membrane potential in Shaker S4 segments. S4 immobilization after a UV flash can be prevented by depolarization of Shaker channels, suggesting that movement in the activation pathway is capable of separating the ketyl and alkyl free radicals. Exploiting the unique charge movement and gating properties of the L382V mutant of Shaker, we show that free radical separation follows S4 movement itself and is relatively independent of the movement of activation gates.

Benzophenones↗