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PubMed2003

Cytotoxic benzophenone derivatives from Garcinia species display a strong apoptosis-inducing effect against human leukemia cell lines.

We examined the in vitro effects of the benzophenone derivatives garcinol, isogarcinol, and xanthochymol on cell growth in four human leukemia cell lines. All of the compounds exhibited significant growth suppression due to apoptosis mediated by the activation of caspase-3. A loss of mitochondrial membrane potential was found in garcinol- and isogarcinol-induced apoptosis, but not in xanthochymol-induced apoptosis. The growth inhibitory effects of isogarcinol and xanthochymol were more potent than that of garcinol, which is a well- known cytotoxic benzophenone derivative.

Apoptosis↗
PubMedDate not supplied

Polyisoprenylated benzophenones in cuban propolis; biological activity of nemorosone.

The Copey tree (Clusia rosea) has a large distribution in Cuba and its floral resin is a rich source of polyisoprenylated benzophenones. To determine the presence of these natural products, we carried out a study by HPLC of 21 propolis samples produced by honey bees (Apis mellifera) from different provinces of Cuba. Nemorosone resulted to be the most abundant polyisoprenylated benzophenone and the mixture of xanthochymol and guttiferone E was also observed, but in minor proportion. We studied the biological activity of the pure natural product nemorosone and its methyl derivatives. We found that nemorosone has cytotoxic activity against epitheloid carcinoma (HeLa), epidermoid carcinoma (Hep-2), prostate cancer (PC-3) and central nervous system cancer (U251). It also exhibited antioxidant capacity. Methylated nemorosone exhibited less biological activity than the natural product.

Animals↗
PubMed2001

Comparison of DNA damage photoinduced by ketoprofen, fenofibric acid and benzophenone via electron and energy transfer.

Ketoprofen (KP) and fenofibrate, respectively, anti-inflammatory and hypolipidemiant agents, promote anormal photosensitivity in patients and may induce photoallergic cross-reactions correlated to their benzophenone-like structure. Here, their ability to photosensitize the degradation of biological targets was particularly investigated in DNA. The photosensitization of DNA damage by KP and fenofibric acid (FB), the main metabolite of fenofibrate, and their parent compound, benzophenone (BZ), was examined on a 32P-end-labeled synthetic oligonucleotide in phosphate-buffered solution using gel sequencing experiments. Upon irradiation at lambda > 320 nm, piperidine-sensitive lesions were induced in single-stranded oligonucleotides by KP, FB and BZ at all G sites to the same extent. This pattern of damage, enhanced in D2O is characteristic of a Type-II mechanism. Spin trapping experiments using 2,2,6,6-tetramethyl-4-piperidone have confirmed the production of singlet oxygen during drug photolysis. On double-stranded oligonucleotides, highly specific DNA break occurred selectively at 5'-G of a 5'-GG-3' sequence, after alkali treatment. Prolonged irradiation led to the degradation of all G residues, with efficiency decreasing in the order 5'-GG > 5'-GA > 5'-GC > 5'-GT, in good agreement with the calculated lowest ionization potentials of stacked nucleobase models supporting the assumption of a Type-I mechanism involving electron transfer, also observed to a lesser extent with adenine. Cytosine sites were also affected but the action of mannitol which selectively inhibited cytosine lesions suggests, in this case, the involvement of hydroxyl radical, also detected by electronic paramagnetic resonance using 5,5-dimethyl-1-pyrrolidine-1-oxide as spin trap. On a double-stranded 32P-end-labeled 25-mer oligonucleotide containing TT and TTT sequences, the three compounds were found to photosensitize by triplet-triplet energy transfer the formation of cyclobutane thymine dimers detected using T4 endonuclease V.

Anticholesteremic Agents↗
PubMed2003

Solid-liquid extraction and preconcentration of trace nickel using 2-nitroso-1-naphthol-4-sulfonic acid (Nitroso-S) and TDBA onto benzophenone and determination by atomic absorption spectrometry.

Nickel was quantitatively retained by 2-nitroso-1-naphthol-4-sulfonic acid (Nitroso-S) and tetradecyldimethylbenzylammonium chloride (TDBA Cl) onto benzophenone in the pH range 5.0-6.0 from large volumes of aqueous solutions of various samples. After filtration, each solid mass consisting of a nickel complex and benzophenone was dissolved with 5 ml of dimethylformamide (DMF) and the metal was determined by atomic absorption spectrometry (AAS). About 0.6 microg of nickel could be concentrated from 200 ml of an aqueous sample, where its concentration was as low as 3.0 ng/ml. Eight replicate determinations of 2.5 microg/ml of nickel in the final DMF solution gave a mean absorbance of 0.112 with a relative standard deviation of 1.9%. The sensitivity for 1% absorption was 98 ng/ml. The interference of a number of anions and cations was studied and the developed optimized conditions were utilized for the trace determination of nickel in various alloys and biological samples.

Alloys↗
PubMed2002

[Determination of alkylphenols, bisphenol A, benzophenone and phthalates in containers of baby food, and migration into food simulants].

Infants, whose growth and development are highly dependent upon the endocrine system, are particularly vulnerable to endocrine disruptor exposure. In our study, we examined whether or not alkylphenols, bisphenol A, benzophenone, di(2-ethylhexyl)adipate and 10 phthalates are present in containers of baby food. Furthermore, the migration into food-simulating solvents was also examined. Sixteen types of containers of baby food, obtained on the Japanese market in 2001, were examined: 8 glass bottle types, 1 plastic type, 1 metallic package (laminated with plastic) and 6 multilayered laminated film packages. Alkylphenols, benzophenone, bisphenol A and di(2-ethylhexyl)adipate were not detected in any of the samples. On the other hand, dibutylphthalate (DBP) was detected in 7 samples (1.2-9.1 micrograms/sample), and di(2-ethylhexyl)phthalate (DEHP) was detected in 15 samples (1.3-18 micrograms/sample). Migration tests were carried out for 5 samples, and the levels of DBP and DEHP that migrated into n-heptane were 0.68-1.7 micrograms/sample and 0.33-3.5 micrograms/sample, respectively. From these results, a baby's intake levels of DBP and DEHP were estimated to be about 1/2,500 and 1/90-300 of the tolerable daily intake (TDI), respectively.

Alkylation↗
PubMed2006

Activity related to the carcinogenicity of plastic additives in the benzophenone group.

This study examines the activities relating to the carcinogenicity of six types of benzophenone derivatives (benzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone) currently used in plastic products as additives to serve as ultraviolet absorbing agents. The evaluation of the initiation activity used a light absorption umu-test, a luminescent umu-test and the Ames test. The promotion activity was examined by a Bhas assay, a method that uses Bhas 42 cells for the formation of transformation foci. The luminescent umu-test indicated positive initiation activity of 2-hydroxy-4-methoxybenzophenone, and pseudo-positive activity of 2,4-dihydroxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone. In the Ames test, 2-hydroxy-4-octyloxybenzophenone showed pseudo-positive initiation activity. Conversely, 2,4-dihydroxybenzophenone indicated weak promotion activity at 10 microg/ml concentration.

Benzophenones↗
PubMed2004

Improved activity and stability of alkaline phosphatases from psychrophilic and mesophilic organisms by chemically modifying aliphatic or amino groups using tetracarboxy-benzophenone derivatives.

The activity-stability-structure relationship of the cold-active alkaline phosphatase from Red Arctic shrimp, Pandalus borealis (SAP) was studied by chemically modifying aliphatic (C-H) or amino (NH2) groups using benzophenone tetracarboxylic derivatives in either a light (UV-A) or dark reaction. The response of the cold-adapted enzyme was compared to a similarly modified calf alkaline phosphatase (CAP). MALDI-TOF-MS was used to determine the extent and nature of the modifications in both SAP and CAP. On average 2 to 4 amino acid residues were linked to a BP-modifier, with up to 18 to 21 amino acids modified in a smaller portion of the material. The effect of the modifications on kinetic and thermodynamic properties varied with the enzyme and type of modification. The aliphatic-group modified SAP demonstrated typical characteristics of a mesophilic enzyme, consistent with an activity-stability trade-off where gain in thermostability was attained at the expense of decreased activity. In contrast, the activity of the amino-group modified SAP attained an even more psychrophilic character with respect to its kinetic (increase in kcat and Km) and thermodynamic (reduction in deltaH#) properties. Interestingly, the amino-group modified SAP also acquired higher thermostability, thus demonstrating that both activity and stability can be simultaneously enhanced using chemical modification. The study demonstrates the applicability of benzophenone chemical modification for improving the thermal properties of enzymes from psychrophiles and mesophiles.

Alkaline Phosphatase↗
PubMed1989

Benzodiazepines identified by capillary gas chromatography-mass spectrometry, with specific ion screening used to detect benzophenone derivatives.

We developed algorithms for confirmation and identification of benzodiazepines and their metabolites, initially detected in urine samples by enzyme-multiplied immunoassay (EMIT). These algorithms are based on the pattern of benzophenone derivatives of benzodiazepines obtained by gas chromatography-mass spectrometry (GC-MS) with use of a modified specific ion selection mode. Benzophenone derivatives were produced by acid hydrolysis of urine samples containing benzodiazepines and (or) their metabolites. We present mass spectra of the newer benzodiazepines--alprazolam, midazolam, and triazolam--and we determined the detection limit (0.2 mg/L) for these drugs as measured with the EMIT d.a.u. benzodiazepine assay and the ETS instrument (both from Syva Co.). We conclude that these algorithms are useful mostly in forensic toxicology in which unequivocal identification of benzodiazepines is the desired goal.

Alprazolam↗
PubMedDate not supplied

Metabolism of benzophenone-3 in rats.

Benzophenone-3 [2-hydroxy-4-methoxybenzophenone (HMB), oxybenzone, Spectra-Sorb UV-9 light absorber] is used in many cosmetics and sunscreens as a UV absorber. This study was conducted to investigate the metabolism of HMB (100 mg/kg body weight administered orally). 2,4-Dihydroxybenzophenone (DHB), 2,2'-dihydroxy-4-methoxybenzophenone (DHMB), and 2,3,4-trihydroxy-benzophenone (THB) metabolites were identified as free and conjugated forms by HPLC analysis. HMB was rapidly absorbed, metabolized, and detected in plasma (as free and protein bound) at 5 min postadministration. The parent compound and metabolites (free and conjugated) were detected at 6 hr in most tissues. DHB was present in most tissues with the highest concentration in the liver. DHMB was only detected as the conjugated form in liver, spleen, and heart. Trace amounts of THB were also detected in biological samples. Urine was the primary route, whereas feces was the secondary route of elimination of HMB and its metabolites. This study revealed O-dealkylation as the major pathway of HMB metabolism.

Animals↗
PubMed2006

Properties of excited ketyl radicals of benzophenone analogues affected by the size and electronic character of the aromatic ring systems.

The properties of benzophenone ketyl radical analogues with large aromatic ring systems, such as naphthylphenylketone (2), 4-benzoylbiphenyl (3), and bis(biphenyl-4-yl)methanone (4), were investigated in the excited state by using nanosecond-picosecond two-color two-laser flash photolysis. Fluorescence and transient absorption spectra of ketyl radicals of 2-4 in the excited state were observed for the first time. The fluorescence and properties of the excited ketyl radicals were significantly affected by the size and electronic properties of the aromatic ring systems. The reactivity of the ketyl radicals in the excited state with several quenchers was examined and they were found to show reactivity toward N,N-diethylaniline. In addition, for the benzophenone ketyl radical, a unique quenching process of the radical in the excited state by the ground-state parent molecule was found. The factors regulating the fluorescence lifetime of the ketyl radicals in the excited state are discussed quantitatively.

Journal Article↗
PubMed1996

Benzophenone synthase from cultured cells of Centaurium erythraea.

A central step in xanthone biosynthesis is the formation of the C13 skeleton, i.e. an intermediate benzophenone. Biosynthesis of 2,3',4,6-tetrahydroxybenzophenone from m-hydroxybenzoyl-CoA and malonyl-CoA was shown in cell-free extracts from cultured cells of Centaurium erythraea. The enzyme catalyzing this reaction was named benzophenone synthase.

Acyl Coenzyme A↗
PubMed2002

Hammett rho of reactions of MeLi with benzophenones.

Relative rates of reactions of MeLi with benzophenones in diethyl ether at 0 degrees C that furnish methyldiarylmethanols were determined using slow addition of a MeLi solution to solutions containing an excess of two benzophenones. The additions exhibit a Hammett rho of 0.94.

Journal Article↗
PubMed2005

Origin of a large temperature dependence of regioselectivity observed for [2 + 2] photocycloaddition (Paternò-Büchi reaction) of 1,3-dimethylthymine with benzophenone and its derivatives: conformational property of the intermediary triplet 1,4-diradicals.

[reaction: see text] The [2 + 2] photochemical additions of 1,3-dimethylthymine (DMT) with benzophenone and its 4,4'-substituted derivatives (BPs), difluoro, di-tert-butyl, and dimethoxy benzophenones, have been investigated at a temperature range from -40 to 70 degrees C. The photochemical reactions, which are cycloaddition of the 5-6 double bond of DMT with the carbonyl group of BPs, the so-called the Paternò-Büchi (PB) reaction, reveal largely temperature-dependent regioselectivity. The chemical yields of one series of regioisomers, 2, decrease with the increase of the reaction temperature, but those of another regioisomer series, 3, increase, and thus the ratio of 2/3 is strongly dependent on the temperature (2/3 = ca. 70:30 to 30:70). The temperature dependence of the regioselectivity yields two linear functions in the corresponding Eyring diagrams. The Eyring plot with changed slopes is clearly indicative of the change for the selectivity-determining step in the PB reaction, in which the triplet 1,4-diradicals play a crucial role. Computational studies reveal the conformational equilibrium structures of the triplet 1,4-diradicals, energy barriers between the conformers, and the conjectural equilibrium constants from relative potential energies of the stable conformers. A proposed mechanism can reasonably explain the temperature-dependent regioselectivity and chemical yields of two regioisomers varying with the reaction temperature.

Journal Article↗
PubMed2005

Contrastive photoreduction pathways of benzophenones governed by regiospecific deprotonation of imidazoline radical cations and additive effects.

[Reaction: see text]. In the photoreaction of benzophenones with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI), benzhydrols were major products. Addition of H2O accelerated the reaction with no change in the product distribution, while AcOH, PhOH, and metal salts such as LiClO4 and Mg(ClO4)2 were effective additives to produce benzpinacols. In contrast, benzpinacols were exclusively formed regardless of the solvent and the additive in the reactions with 2-(o-hydroxyphenyl)-1,3-dimethylbenzimidazoline (o-HPDMBI). These observations are consistent with the hypothesis that DMPBI*+ donates a proton at the C2 position to the benzophenone ketyl radicals while o-HPDMBI*+ donates a phenol proton.

Journal Article↗
PubMed2002

Photoreduction of benzophenones by amines in room-temperature ionic liquids.

[reaction: see text] The amine-mediated photoreduction of benzophenones in room temperature ionic liquids was investigated. Unlike the analogous reaction in organic solvents, the photoreduction produces mainly the corresponding benzhydrol in most cases. Because the reaction consumes only 1 equiv of amine and the solvent can be easily recycled, the photoreduction allows a very clean method for the conversion of benzophenones to benzhydrols.

Journal Article↗
PubMed2005

Formal intramolecular photoredox chemistry of meta-substituted benzophenones.

[reaction: see text]. Photolysis of 3-(hydroxymethyl)benzophenone (1) in aqueous solution (pH < 3) results in clean formation of 3-formylbenzhydrol (2) at dilute (<10(-4) M) conditions. Evidence suggests that the highly efficient (Phi approximately 0.6) reaction involves a unimolecular mechanism and an overall formal intramolecular photoredox process, which requires electronic communication between the 1,3-positions of the benzene ring, an unprecedented example of the photochemical meta effect. The photoredox reaction was not observed in organic solvents, where only photoreduction of the benzophenone moiety was observed.

Journal Article↗
PubMed2006

Catalytic enantioselective borohydride reduction of ortho-fluorinated benzophenones.

[reaction: see text] In the presence of the optically active ketoiminatocobalt(II) complexes, the enantioselective borohydride reduction of benzophenones was successfully completed. The fluorine atom on the ortho position of the benzophenone and aryl ketones proved effective for obtaining high enantioselectivities. The combined use of modified lithium borohydride afforded the corresponding benzhydrols and arylcarbinols in high yield and high enantioselectivity (88-96% ee).

Journal Article↗