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Results for “Benzophenones”

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PubMed1999

GC-MS determination of flunitrazepam and its major metabolite in whole blood and plasma.

A gas chromatography-mass spectrometry method was developed for the analysis of flunitrazepam (FN) and its major metabolite, 7-amino-flunitrazepam (7-amino-FN), in both plasma and whole blood. The method was based on acid hydrolysis of the samples after dilution with HPLC water followed by extraction and derivatization (heptafluorobutyrate) of the resulting benzophenones. Analysis of plasma and whole blood samples from subjects administered 2-mg doses of FN showed that FN was only detected in whole blood (LOD 5 ng/mL) and not in plasma. However, 7-amino-FN was detected in both plasma and whole blood, although the levels were much higher in plasma. 7-Amino-FN was detected for the entire period of specimen collection (12 h), but FN was only detected in whole blood for 4 h after ingestion with peak levels after 1 h.

Anti-Anxiety Agents↗

PubMed2005

Asymmetric photocross-linking of singly phosphorylated smooth muscle heavy meromyosin.

Although activities of smooth muscle myosin are regulated by phosphorylation, the molecular mechanisms of regulation have not been fully established. Phosphorylation of both heads of myosin is known to activate ATPase and motor activities, but the effects of phosphorylation of only one of the heads have not been established. Such information on singly phosphorylated myosin can serve to elucidate the molecular mechanism of the phosphorylation-dependent regulation. To understand the structural properties of the singly phosphorylated state, we prepared singly phosphorylated heavy meromyosin (HMM) containing a photoreactive benzophenone-labeled RLC and examined its photocross-linking reactivity. The two heads in the singly phosphorylated HMM showed different reactivities. The dephosphorylated RLC in the singly phosphorylated HMM was cross-linked to a heavy chain, like that in the dephosphorylated HMM, whereas the phosphorylated RLC did not react, like that in the fully phosphorylated HMM. These results indicate that the two heads of the singly phosphorylated HMM have an asymmetric structure, suggesting that phosphorylation of one head can to some extent activate smooth muscle HMM.

Amino Acid Sequence↗

PubMed1994

Effect of sunscreens on UV radiation-induced enhancement of melanoma growth in mice.

BACKGROUND: Epidemiologic evidence suggests that exposure to UV radiation plays a significant role in the development of melanoma skin cancers. As early surgical removal of the melanoma is the only effective therapy, current strategies for reducing mortality from melanoma focus on prevention of the disease. Chemical sunscreens protect mice from development of skin cancers that resemble sunlight-induced human squamous cell cancers, but there appears to be a complex relationship between UV radiation exposure and development of melanoma. PURPOSE: We asked whether common sunscreens would protect mice against UV radiation-induced enhancement of melanoma incidence. METHODS: C3H mice were exposed to 4.8 kJ/m2 UVB from FS40 sunlamps twice a week for 3 weeks. Sunscreens containing 7.5% 2-ethylhexyl-p-methoxycinnamate, 8% octyl-N-dimethyl-p-aminobenzoate, 6% benzophenone-3, or the oil-in-water vehicle alone were applied to the ears and tails of the mice 20 minutes before irradiation. At various times during and after exposure, we determined UV radiation-induced inflammation by measuring ear swelling. We also examined the ears histologically for UV radiation-induced alterations. One day after the final irradiation, 2.5 x 10(4) syngeneic K1735 melanoma cells were injected into the external ears. Mice were examined weekly for tumor growth for 5-8 weeks after tumor cell injection. Control mice were treated in the identical way except for exposure to UV radiation. RESULTS: The incidence of melanomas was significantly higher in the UV-irradiated mice. All three sunscreens protected against UV radiation-induced ear swelling and clearly diminished histopathologic alterations, including sunburn cell formation, epidermal hyperplasia, and mononuclear cell infiltrate in the dermis. However, the sunscreens failed to protect against UV radiation-induced increase in melanoma incidence. The sunscreens or vehicle alone did not significantly alter tumor growth. CONCLUSIONS: Protection against sunburn does not necessarily imply protection against other possible UV radiation effects, such as enhanced melanoma growth. IMPLICATIONS: Sunscreen protection against UV radiation-induced inflammation may encourage prolonged exposure to UV radiation and thus may actually increase the risk of melanoma development. These findings suggest that further research on the ability of sunscreens to prevent melanoma is urgently needed.

4-Aminobenzoic Acid↗

PubMed2006

Identifying an interaction site between MutH and the C-terminal domain of MutL by crosslinking, affinity purification, chemical coding and mass spectrometry.

To investigate protein-protein interaction sites in the DNA mismatch repair system we developed a crosslinking/mass spectrometry technique employing a commercially available trifunctional crosslinker with a thiol-specific methanethiosulfonate group, a photoactivatable benzophenone moiety and a biotin affinity tag. The XACM approach combines photocrosslinking (X), in-solution digestion of the crosslinked mixtures, affinity purification via the biotin handle (A), chemical coding of the crosslinked products (C) followed by MALDI-TOF mass spectrometry (M). We illustrate the feasibility of the method using a single-cysteine variant of the homodimeric DNA mismatch repair protein MutL. Moreover, we successfully applied this method to identify the photocrosslink formed between the single-cysteine MutH variant A223C, labeled with the trifunctional crosslinker in the C-terminal helix and its activator protein MutL. The identified crosslinked MutL-peptide maps to a conserved surface patch of the MutL C-terminal dimerization domain. These observations are substantiated by additional mutational and chemical crosslinking studies. Our results shed light on the potential structures of the MutL holoenzyme and the MutH-MutL-DNA complex.

Adenosine Triphosphatases↗

PubMed2000

The estrogen receptor relative binding affinities of 188 natural and xenochemicals: structural diversity of ligands.

We have utilized a validated (standardized) estrogen receptor (ER) competitive-binding assay to determine the ER affinity for a large, structurally diverse group of chemicals. Uteri from ovariectomized Sprague-Dawley rats were the ER source for the competitive-binding assay. Initially, test chemicals were screened at high concentrations to determine whether a chemical competed with [3H]-estradiol for the ER. Test chemicals that exhibited affinity for the ER in the first tier were subsequently assayed using a wide range of concentrations to characterize the binding curve and to determine each chemical's IC50 and relative binding affinity (RBA) values. Overall, we assayed 188 chemicals, covering a 1 x 10(6)-fold range of RBAs from several different chemical or use categories, including steroidal estrogens, synthetic estrogens, antiestrogens, other miscellaneous steroids, alkylphenols, diphenyl derivatives, organochlorines, pesticides, alkylhydroxybenzoate preservatives (parabens), phthalates, benzophenone compounds, and a number of other miscellaneous chemicals. Of the 188 chemicals tested, 100 bound to the ER while 88 were non-binders. Included in the 100 chemicals that bound to the ER were 4-benzyloxyphenol, 2,4-dihydroxybenzophenone, and 2,2'-methylenebis(4-chlorophenol), compounds that have not been shown previously to bind the ER. It was also evident that certain structural features, such as an overall ring structure, were important for ER binding. The current study provides the most structurally diverse ER RBA data set with the widest range of RBA values published to date.

Animals↗

PubMed1987

An animal model for evaluation of topical photoprotection against ultraviolet A (320-380 nm) radiation.

Recent studies reporting UVA (ultraviolet A radiation 320-380 nm) as an integral part of the cumulative sun-induced damage in human skin have prompted an interest in developing effective UVA photoprotective agents. The development of such compounds has been impeded by the absence of a clinically relevant animal model for evaluating their efficacy. This report describes the development and use of such a laboratory animal system. Selected concentrations of oxybenzone (2-hydroxy-4-methoxybenzophenone) in vehicle (0.1% to 6%) or vehicle alone were applied to the depilated dorsal skin of 30 Hartley strain female albino guinea pigs. The skin was irradiated with solar simulated UVA from a xenon light source. Acute radiation-induced damage was assayed by erythema grading and inhibition of [3H]thymidine incorporation into epidermal DNA. Data from erythema grading studies indicated that a significant degree of photoprotection was achieved with 6%, 3%, and 1% solutions of benzophenone compared with the control vehicle; the 6% solution was significantly more photoprotective than the 3% and 1% solutions. A 6% solution afforded significant photoprotection when assayed by [3H]thymidine incorporation.

Administration, Topical↗

PubMed1983

Ornithine decarboxylase induction in psoralen-treated mouse epidermis used as a test of UV-A sunscreen potency.

Inhibition by sunscreens of UV-A-induced epidermal ornithine decarboxylase (ODC) activity in 8-methoxypsoralen-treated mice was used to examine the UV-A sunscreen activity of two commercial preparations, Uval (para-aminobenzoic acid) and PreSun (a benzophenone derivative). Both gave significant protection against UV-A doses of up to 3 J/cm2 and Uval was more effective that PreSun in the UV-A range. At intermediate doses (5-15 J/cm2) neither Uval nor PreSun significantly altered the ODC response to UV-A. At doses of 20-40 J/cm2 UV-A, control and PreSun-treated animals showed a decline in ODC activity which histological studies suggested was due to severe epidermal damage. This decline in ODC activity and severe epidermal damage was not seen in Uval-treated animals. Topical zinc oxide was highly effective in preventing induction of ODC by UV-A irradiation at doses up to 40 J/cm2, and was significantly more effective than either PreSun or Uval.

4-Aminobenzoic Acid↗

PubMed1994

Photoallergic contact dermatitis to oxybenzone.

A 21-year-old woman developed an erythematous papulovesicular eruption of photo-exposed sites, following the use of an oxybenzone-containing sunscreen. Patch testing, photopatch testing, phototesting, and histology produced findings strongly suggestive of oxybenzone photoallergy. Photopatch testing with a monochromator source showed abnormal UVA responses, with evidence of immediate urticaria, and delayed-onset dermatitis. Sun-barrier use is associated with a risk of the development of contact or photocontact allergic reactions. The benzophenones are frequently used in high-protection factor sun-barrier preparations, and appear to have a particular ability to induce such responses.

Adult↗

PubMed1988

Randomized, double-blind trial of exifone versus cognitive problems in Parkinson's disease.

Exifone is a novel substance of the benzophenone group that possesses potent scavenging properties. Initial findings demonstrate beneficial effects on age-related cognitive disorders. In this double-blind clinical trial versus placebo, the efficacy of 2 dosages (600 and 1200 mg/d) was evaluated with regard to Parkinson's disease (PD)-related cognitive disorders, for which there is increasing suspicion of a free-radicals origin. Despite disparities between the treatment groups as assessed by validated scales and subtests, and a considerable placebo effect on main parameters, both dose levels of exifone produced statistically significant improvement of the cognitive items most commonly impaired by PD: immediate recall, naming of objects presented, spatiotemporal orientation, and calculation. These properties suggest a new slot for exifone in the range of therapeutics available.

Aged↗

PubMed1993

Contact allergy to sunscreen chemicals in photosensitivity dermatitis/actinic reticuloid syndrome (PD/AR) and polymorphic light eruption (PLE).

From 1989-1991, 214 patients (45 PD/AR, 54 PLE, 115 controls) were patch tested to a sunscreen series containing 9 constituents. 16/214 (7.5%) patients reacted to one or more sunscreens, with allergy being significantly more common in PD/AR patients (10/45 versus 2/54 PLE and 4/115 contact dermatitis clinic controls). The benzophenone group of sunscreens (mexenone, oxybenzone) were the most frequent sensitizers, accounting for 8 of the 27 positive patch tests observed. Clinicians should consider contact allergy to sunscreens in PD/AR patients as an explanation for exposed-site dermatitis episodes.

4-Aminobenzoic Acid↗

PubMed1990

Characterization of radical adducts formed during photochemical spin trapping in liposomes.

There exists an urgent need to monitor radical reactions in biological membranes. With the exception of a few studies in model and natural membranes, most biological spin trapping reactions have been confined to homogeneous media. In the present work we have devised a methodology by which spin trapping reactions can be investigated in liposomes composed of a fully-saturated phospholipid, dimyristoylphosphatidylcholine. Using photochemical spin trapping, we have detected and characterized the formation and partitioning of spin adducts in liposomes. Benzophenone (a lipid-soluble photosensitizer) and benzoyl peroxide (a lipid-soluble radical initiator) have been used to generate free radicals from hydrogen donors during photolysis in liposomes. Both water-soluble and lipid-soluble spin traps have been used to trap the radicals.

Benzophenones↗

PubMed1984

Microbial removal of wastewater organic compounds as a function of input concentration in soil columns.

The fate of six organic compounds during rapid infiltration of primary wastewater through soil columns was studied. Feed solutions were prepared which contained all six compounds in individual concentrations ranging from 1 to 1,000 micrograms/liter and were applied to separate soil columns on a flooding-drying schedule. Feed solutions and column effluents were analyzed for the compounds by XAD resin (Rohm and Haas Co.) extraction and gas chromatography-mass spectrometry during each of three successive inundation cycles. Breakthrough profiles of o-phenylphenol were relatively consistent during the test, with fractional breakthrough (mass output/mass input) being independent of input concentration. Consistent profiles were also observed for 2-(methylthio)benzothiazole, although fractional breakthroughs were higher at lower input concentrations, indicating that removal processes were operating less efficiently at these levels. The behavior of p-dichlorobenzene was similar to that of 2-(methylthio)benzothiazole after the first inundation cycle, with the exception that increased fractional breakthroughs were observed at the highest input concentration as well. Microbial adaptation was evident for benzophenone, 2-methylnaphthalene, and p-(1,1,3,3-tetramethylbutyl)phenol, as indicated by increased removal efficiencies during successive inundation cycles, especially at the higher input concentrations. Column effluent concentrations of the latter two compounds were independent of input concentrations during the final stage of the test. Microbial activity and adaptation were confirmed for several of the compounds by using isotopes and measuring the extent of mineralization in batch tests with soil from one of the columns.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzophenones↗

PubMedDate not supplied

Percutaneous absorption of sunscreens in vitro: interspecies comparison, skin models and reproducibility aspects.

Appropriate evaluation of sunscreens is required to provide better knowledge of their safety and efficacy. One of the most important elements of this evaluation is the assessment of percutaneous absorption. In vitro methods are largely used for such assessments, and the accuracy of the measurements generated with these methods depends on the use of a proper methodology. This study was designed to evaluate an in vitro protocol for investigating the percutaneous absorption of two sunscreens under standardized experimental conditions. Octyl methoxycinnamate and benzophenone 4 were each incorporated in a typical oil-in-water emulsion and tested separately. Salicylic acid was tested as a reference compound. In vitro percutaneous absorption was evaluated using two species, the pig and human, and two models, full-thickness and split-thickness skin. The reproducibility of study results was evaluated by comparing the data generated by two industrial laboratories, L'Oréal and Hoffmann-La Roche. The correlation of quantitative data between pig skin and human skin was very good, and the split-thickness skin model seemed to be more appropriate for measuring the absorption of sunscreens. Results obtained for salicylic acid demonstrated the relevance of the protocol in terms of prediction of in vivo percutaneous absorption. Finally, the comparison of pig skin data between the two laboratories demonstrated a good correlation and underlined the need for a standardized in vitro procedure.

Animals↗

PubMedDate not supplied

Skin penetration and sun protection factor of five UV filters: effect of the vehicle.

To gain information about efficacy and safety of sunscreens, we compared the skin penetration of ultraviolet (UV) filters from two vehicles, i.e. an oil-in-water (O/W) emulsion gel and petrolatum jelly both in vitro and in vivo, as well as the corresponding pharmacological effect, i.e. the sun protection factor (SPF) in vivo. The UV filters studied were benzophenone-3 (BPH), ethylhexyl methoxycinnamate (EHM), butyl methoxydibenzoyl methane, ethylhexyl salicylate and homosalate. The human skin penetration of these five chemicals from the two vehicles was determined both in vitro using Franz cells and in vivo using a standardized tape-stripping method. The SPF of the two sunscreens was determined in vivo following the COLIPA guidelines. In vitro none of the filters permeated through the skin after 6 h of product application and very little could be found in the skin. BPH and EHM were the only UV filters found in the dermis (both after 30 min and 6 h). An effect of the vehicle could be noticed only for BPH after 30 min in the dermis and 6 h in both dermis and epidermis. In vivo, no differences in the amount of individual UV filters (in % of the applied dose) in the 15 first strips of the stratum corneum (SC) were found following 30 min of application of the formulations; however, the amount of UV filters that were retained in the SC was significantly higher (around 3 times) with the O/W emulsion gel than with the petrolatum jelly. This difference between the two vehicles was also of consequence for the SPF in vivo measured 30 min after application of the products (SPF congruent with 18 with the O/W emulsion gel compared to SPF congruent with 10 with the petrolatum jelly). By choosing the right vehicle or optimizing it, not only sunscreen products can be significantly improved in terms of pharmacological efficacy but the potential toxicological risk associated with the skin penetration of UV filters may be significantly reduced.

Adult↗

PubMed1998

Chemical modification and photograft polymerization upon expanded poly(tetrafluoroethylene).

Poly(tetrafluoroethylene) (PTFE) films were surface-modified by employing a reaction solution of benzophenone and sodium hydride in anhydrous dimethylformamide at a temperature of 150 degrees C for 12 h. Electron spectroscopy for chemical analysis (ESCA) showed defluorination, oxygen incorporation, and extensive unsaturation within the treated PTFE surfaces. The suitably of these reduced PTFE films as substrates for graft polymerization was initially assessed via photograft polymerization of the sodium salt of styrenesulfonic acid (SS-Na), which permitted unequivocal surface analysis by the introduction of a new atom, as well as poly(ethylene glycol) monoacrylate (PEG-Ac). All photograpt polymerization was performed employing ultraviolet irradiation with 2,2-dimethoxy-2-phenylacetophenone as an initiator. Photograft polymerization of SS-Na was verified by further reduction of fluorine atomic content and the appearance of new sulfur and sodium atomic peaks on ESCA survey spectra, and that of PEG-Ac was verified by further reduction of fluorine atomic content and increase of atomic percent ratio of O/C from ESCA survey spectra as well as appearance of a new ester peak on high resolution ESCA C 1s spectra. Dynamic water contact angles on reduced and PEG-Ac photograft polymerized films were measured and showed that the PTFE film surface became more hydrophilic after reduction (from 120 to 89 deg) and the reduced film became more hydrophilic after photograft polymerization with PEG-Ac (from 89 to 36 deg). Modification of the complete surface of expanded PTFE (ePTFE), i.e. of the lumenal, outside and pore surfaces, was performed by employing the reaction described above, except at 105 degrees C for 1 day, followed by photograft polymerization of PEG-Ac. ESCA was performed on the superficial surfaces (i.e. the lumen and exterior) as well as on cross-sections of the ePTFE to permit analysis of the pore surfaces. This analysis showed that both the initial surface reduction and subsequent photograft polymerization were successful as indicated from F/C and O/C atomic percent ratios from ESCA survey spectra, from overall peaks shapes of high resolution ESCA C 1s spectra and from generation of new ester peaks on high resolution ESCA C 1s spectra of ePTFE graft polymerized with PEG-Ac, which demonstrated an O/C atomic percent ratio close to that of PEG-Ac homopolymer. Low voltage scanning electron microscopy confirmed minimal morphological damage to the ePTFE microstructure after reduction and graft polymerization. The approach explored thus provides a means for modulation of biological interactions at ePTFE surfaces with only minimal modification of material morphology, with some surface texture appearing on a length scale of 50-100 nm.

Benzophenones↗

PubMed2004

In vitro estrogenicity of resin composites.

Previously, we have reported that sealants incorporating bisphenol A dimethacrylate showed estrogenicity by a reporter gene assay. This study tested the hypothesis that commercial composites, which contain various monomers and additives, exhibit estrogenic activity in vitro. The estrogenic activities of eluates obtained from 24 composites and 18 chemicals identified from the composites tested were examined with the use of the reporter gene assay. Among the 24 composites, 6 products were estrogenic, and among the 18 constituents, 1 photostabilizer, 2-hydroxy-4-methoxy-benzophenone (HMBP), 1 photoinitiator, 2,2-dimethoxy-2-phenyl-acetophenone (DMPA), and 1 inhibitor, 2,6-di-tert-butyl-p-cresol (BHT) had significant estrogenic activity. The concentration of HMBP in 4 estrogenic eluates was greater than the minimum concentration required for estrogenicity, and DMPA was found at a higher level than the minimum estrogenic concentration in the remaining 2 estrogenic specimens. These results suggest that the observed estrogenic activity of 6 composites is associated with the elution of either HMBP or DMPA.

Acetophenones↗

PubMed2004

Polymeric nanoparticles composed of fatty acids and polyvinylalcohol for topical application of sunscreens.

Benzophenone-3 (BZP) or oxybenzone is widely used in many cosmetic formulations, such as sunscreen lotions or emulsions, shampoos and hair sprays. The nature of the vehicle used can enhance or block the percutaneous absorption of UV filter. In this work, we hydrophobically modified polyvinylalcohol 10 000 (PVA) with fatty acids (FAs) to obtain PVA-FA derivatives for the preparation of lipophilic polymeric nanoparticles able to prevent BZP movement towards the skin. Synthesized PVA-FA derivatives were confirmed by H1 NMR. Nanoparticles loaded with BZP were prepared using a solvent extraction method. The particle size was monitored by means of dynamic light scattering measurements. In-vitro skin permeation studies were performed.

Administration, Topical↗

PubMed2005

Four new phenones from the cortexes of Polygala tenuifolia.

From the 95% EtOH extract of the cortexes of Polygala tenuifolia, four new phenones and three known xanthones were isolated. The structures of the four new phenones were identified as 4-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl]-2-hydroxyl-6-methoxybenzophenone (tenuiphenone A, 1), 3,5-di-C-beta-glucopyranosyl-2,4,6,3'-tetrahydroxybenzophenone (tenuiphenone B, 2), 2',4',6'-trihydroxyphenyl-(24Z)-triacontene-1-one (tenuiphenone C, 3), 2',4',6'-trihydroxyphenyl-(26Z)-dotriacontene-1-one (tenuiphenone D, 4) respectively, on the basis of spectroscopic analyses. The isolation of 1 and 2 supplied an evidence for the hypothesis that xanthone was biosynthesized from benzophenone in the plants.

Benzophenones↗