Objective Hydroquinone(HQ),one of the phenolic metabolites of benzene,is widely recognized as an important participant in benzene-induced hematotoxicity.However,there are few relevant proteomics in HQ-induced hematoto...Objective Hydroquinone(HQ),one of the phenolic metabolites of benzene,is widely recognized as an important participant in benzene-induced hematotoxicity.However,there are few relevant proteomics in HQ-induced hematotoxicity and the mechanism hasn’t been fully understood yet.Methods In this study,we treated K562 cells with 40μmol/L HQ for 72 h,examined and validated protein expression changes by Label-free proteomic analysis and Parallel reaction monitoring(PRM),and performed bioinformatics analysis to identify interaction networks.Results One hundred and eighty-seven upregulated differentially expressed proteins(DEPs)and 279 downregulated DEPs were identified in HQ-exposed K562 cells,which were involved in neutrophilmediated immunity,blood microparticle,and other GO terms,as well as the lysosome,metabolic,cell cycle,and cellular senescence-related pathways.Focusing on the 23 DEGs and 5 DEPs in erythroid differentiation-related pathways,we constructed the network of protein interactions and determined 6 DEPs(STAT1,STAT3,CASP3,KIT,STAT5B,and VEGFA)as main hub proteins with the most interactions,among which STATs made a central impact and may be potential biomarkers of HQ-induced hematotoxicity.Conclusion Our work reinforced the use of proteomics and bioinformatic approaches to advance knowledge on molecular mechanisms of HQ-induced hematotoxicity at the protein level and provide a valuable basis for further clarification.展开更多
Objective To explore the toxicological mechanism of hydroquinone in human bronchial epithelial cells and to investigate whether DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone. M...Objective To explore the toxicological mechanism of hydroquinone in human bronchial epithelial cells and to investigate whether DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone. Methods DNA polymerase beta knock-down cell line was established via RNA interference as an experimental group. Normal human bronchial epithelial cells and cells transfected with the empty vector of pEGFP-C1 were used as controls. Cells were treated with different concentrations of hydroquinone （ranged from 10 μmol/L to 120 μmol/L） for 4 hours. MTT assay and Comet assay [single-cell gel electrophoresis （SCGE）] were performed respectively to detect the toxicity of hydroquinone. Results assay showed that DNA polymerase beta knock-down cells treated with different concentrations of hydroquinone had a lower absorbance value at 490 nm than the control cells in a dose-dependant manner. Comet assay revealed that different concentrations of hydroquinone caused more severe DNA damage in DNA polymerase beta knock-down cell line than in control cells and there was no significant difference in the two control groups. Conclusions Hydroquinone has significant toxicity to human bronchial epithelial cells and causes DNA damage. DNA polymerase beta knock-down cell line appears more sensitive to hydroquinone than the control cells. The results suggest that DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.展开更多
The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The...The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The results show that the hydroquinone derivatives are adsorbed on a gold surface with vertical orientation, which makes the electron transfer between the bulk species and the electrode surface easier than that in the case of flat adsorption of hydroquinone derivatives that occurs at a platinum electrode. The formation of the vertical conformation and the rapid process of electron transfer were also confirmed by quantum chemistry calculations. In addition, the pre-adsorbed iodine on the electrodes played a key role on the adsorbed configuration and electron transfer of redox species.展开更多
Hydroquinone(HQ)is an phenolic aromatic compound used in cosmetic medicine as skin lightening material since long time ago.Accordingly the several pathological conditions that observed,the use of HQ for this purpose w...Hydroquinone(HQ)is an phenolic aromatic compound used in cosmetic medicine as skin lightening material since long time ago.Accordingly the several pathological conditions that observed,the use of HQ for this purpose was recently contraindicated.The commonly noted health problem associated with hydroquinone use was contact dermatitis.The present study was designed and conducted to determine the HQ presence and concentrations in ten samples of skin lightening cosmetics available in the local market.GC-MS analysis was employed for detection of HQ qualitatively while HPLC analysis was used as a quantitative analysis for determination of the HQ concentrations in each sample.The results obtained indicated that the overall range of HQ levels in all respected samples ranged from 0.0039%to 0.14%.展开更多
Hydroquinone is potentially carcinogenic and is known to be a skin and respiratory irritant.Hydroquinone is carcinogenic it has been banned in some countries because of fears of a cancer risk[1,2].Animal studies have ...Hydroquinone is potentially carcinogenic and is known to be a skin and respiratory irritant.Hydroquinone is carcinogenic it has been banned in some countries because of fears of a cancer risk[1,2].Animal studies have shown that topically applied retinoic acid can be photocarcinogenic[3].The aim of this study was qualitative and quantitative determination of hydroquinone and retinoic acid contents in facial whitening creams by colour reaction tests,FT-IR after TLC separation and HPLC.展开更多
In this study, an efficient way by plasma induced mutation was applied to improve the hydroquinone degradation capacity of Serratia marcescens AB 90027 （SM27）. The results showed that combined with the selection of ...In this study, an efficient way by plasma induced mutation was applied to improve the hydroquinone degradation capacity of Serratia marcescens AB 90027 （SM27）. The results showed that combined with the selection of hydroquinone tolerance, the mutant with high hy- droquinone degradation ability induced by plasma could be achieved. The best dose for plasma mutation was 15 s, which showed a 47.0% higher positive mutation ratio. Besides, the aimed mutant was markedly different from the parent strain （SM27） in colonial traits while cultivated on Kings media. Finally, the hydroquinone degradation ratio reached 70.5~o using the induced mutant strain with 1500 mg/L hydroquinone （HQ） after 15 days of cultivation as the selective conditions; however, it was only 46.7% for SM27. The improvement of the degradation capacity by the induced mutant with a high concentration of HQ selection was attributed to its faster growth and higher hydroquinone tolerance compared with that of the parent strain.展开更多
The oxidation of hydroquinone(QH_2) was investigated for the first time at liquid/liquid(L/L) interface by scanning electrochemical microscopy(SECM).In this study,electron transfer(ET) from QH_2 in aqueous to ferrocen...The oxidation of hydroquinone(QH_2) was investigated for the first time at liquid/liquid(L/L) interface by scanning electrochemical microscopy(SECM).In this study,electron transfer(ET) from QH_2 in aqueous to ferrocene(Fc) in nitrobenzene (NB) was probed.The apparent heterogeneous rate constants for ET reactions were obtained by fitting the experimental approach curves to the theoretical values.The results showed that the rate constants for oxidation reaction of QH_2 were sensitive to the changes of the dri...展开更多
First total synthesis of triprenylquinone and hydroquinones, three naturally occurringcompound 1, 2 and （±） 3, have been achieved from readily available 2-bromo-5-methyl-1,4-dimethoxybenzene 4 and geranyl bromi...First total synthesis of triprenylquinone and hydroquinones, three naturally occurringcompound 1, 2 and （±） 3, have been achieved from readily available 2-bromo-5-methyl-1,4-dimethoxybenzene 4 and geranyl bromide. The triprenylquinone and hydroquinones precursor were readily prepared with use of a Julia reaction.展开更多
ENOX (ECTO-NOX) proteins are proteins of the external surface of the plasma membrane that catalyze oxidation of both NADH and hydroquinones as well as carry out protein disulfidethiol interchange. They exhibit both pr...ENOX (ECTO-NOX) proteins are proteins of the external surface of the plasma membrane that catalyze oxidation of both NADH and hydroquinones as well as carry out protein disulfidethiol interchange. They exhibit both prion-like and time-keeping (clock) properties. The oxidative and interchange activities alternate to generate a regular period of 24 min in length. Here we report the cloning, expression, and characterization of a plant candidate constitutive ENOX (CNOX or ENOX1) protein from Arabidopsis lyrata. The gene encoding the 335 (165) amino acid protein is found in accession XP-002882467. Functional motifs characteristics of ENOX proteins previously identified by site-directed mutagenesis and present in the candidate ENOX1 protein from plants include adenine nucleotide and copper binding motifs along with essential cysteines. However, the drug binding motif (EEMTE) sequence of human ENOX2 is absent. The activities of the recombinant protein expressed in E. coli were unaffected by capsaicin, EGCg, and other ENOX2-inhibiting substances. Periodic oxidative activity was exhibited both with NAD(P)H and reduced coenzyme Q as substrate. Bound copper was necessary for activity and activity was inhibited by the ENOX1-specific inhibitor simalikalactone D. Addition of melatonin phased the 24-min period such that the next complete period began 24 min after the melatonin addition as appeared to be characteristic of ENOX1 activities in general. Periodic protein disulfide-thiol interchange activity also was demonstrated along with the 2 oxidative plus 3 interchange activity pattern characteristics of the 24-min ENOX1 protein period. Concentrated solutions of the purified plant ENOX1 protein formed insoluble aggregates, devoid of enzymatic activity, resembling amyloid. Activity was restored to aggregate preparations by isoelectric focusing.展开更多
It was tried to prepare temperature and water responsive microcapsules containing hydroquinone as a water soluble core material with the spray drying method. Microcapsules were composed of ethyl cellulose (EC), methyl...It was tried to prepare temperature and water responsive microcapsules containing hydroquinone as a water soluble core material with the spray drying method. Microcapsules were composed of ethyl cellulose (EC), methyl cellulose (MC) and P-N-isopropylacrylamid (PNIPAM). P-N-isopropylacrylamid and methyl cellulose were used as a temperature responsive polymer and as a water responsive polymer, respectively. Ethyl cellulose was the main shell material of microcapsule. At the microencapsulation process, the core and shell materials were dissolved in ethyl alcohol dissolving water (20 wt%) and then, spray-dried to prepare microcapsules. In the fundamental operation, the concentration and molecular weight of methyl cellulose were mainly changed. The releasing rate of hydroquinone was repressed at 40°C and increased at 20°C due to temperature responsive PNIPAM. Furthermore, responsibility to water was increased with the concentration of methyl cellulose.展开更多
Hydroquinone (HQ) is the most important hydroxy aromatic compound which is produced on a large scale. Understanding its fate in the environment is therefore of primary importance to prevent its migration in the soil a...Hydroquinone (HQ) is the most important hydroxy aromatic compound which is produced on a large scale. Understanding its fate in the environment is therefore of primary importance to prevent its migration in the soil and/or the contamination of the aquatic ecosystems. Here we present a column based method to investigate the physicochemical processes controlling the removal from the aqueous phase and the adsorption onto natural quartz sand (NQS), of organic pollutant such as HQ molecules. We will focus on the interactions that occur between the organic pollutant and the NQS substrate. Thus, column reactors filled with NQS were used to investigate the influence of physicochemical parameters such as the ionic strength, the pH, the flow rate, and the nature of the electrolyte cation, on the HQ adsorption from water onto NQS substrate. The data indicate that, when divalent instead of monovalent cations, are present in the effluent water injection phase, and/or when the ionic strength of the effluent increases, the adsorbed HQ amount decreases. Similar decrease of the adsorbed HQ amount was also observed, at constant ionic strength, by increasing either, the pH from 3 to 9, the flow rate Q from 1 to 3 ml·mn-1, or by decreasing the HQ initial concentration, C0 from 30 to 6 mg·L-1. Further, large amount of the organic pollutant (up to 93 wt% of HQ molecules) was removed from the effluent water phase by using NQS column. The overall data seem to indicate that the adsorption of HQ molecules on the NQS surface is mainly controlled by electrostatic interaction forces occurring between the organic molecule polar groups and the inorganic matrix silanol groups.展开更多
Hydroquinone has been used for decades as a skin lightening agent. Its use in cosmetics has been banned as a result of skin problems including contact dermatitis and ochronosis. A total of 22 samples of different skin...Hydroquinone has been used for decades as a skin lightening agent. Its use in cosmetics has been banned as a result of skin problems including contact dermatitis and ochronosis. A total of 22 samples of different skin whitening cosmetics were collected from local market. They were analyzed by using thin layer chromatography and HPLC for qualitative and quantitative determination of their hydroquinone contents. The hydroquinone was extracted from samples by using 96% ethanol and was subjected to TLC analysis. Eleven out of 22 samples were found to contain hydroquinone. The HPLC analysis showed the concentration of hydroquinone ranged from 0.002% to 0.092% in the cosmetic samples.展开更多
Many countries in the world wide banned hydroquinone in cosmetics skin lightening but it is still used in most of Africa countries, including Sudan. Few studies were carried out on the side effect of hydroquinone on S...Many countries in the world wide banned hydroquinone in cosmetics skin lightening but it is still used in most of Africa countries, including Sudan. Few studies were carried out on the side effect of hydroquinone on Sudanese women. Therefore, the present study was carried out in Khartoum state in April to May/2014 to assess the awareness of Sudanese women about using hydroquinone and its probable risks. The results revealed that, highly using cosmetics containing hydroquinone by women aged between 20 - 29 years (78.3%) as well as by those classified as single (69.6%). The results also showed that the highest percentage of women was using it during evening (81.2%) and a high percentage of them was using it for skin lightening (65.2%), followed by elimination acne (20.3%) and about 10.1% for both skin lightening and elimination of acne and very little (4.3%) for freckle elimination. Moreover, the results showed a very high percentage of women (94.2%) used the chemical without being prescribed by doctors and about (85.5%) of them didn’t know its nature and risks on human health. Consequently, (50.7%) of women have had sides effects, (44.9 %) used more than one and (44.1%) used it regularly. In addition, the results revealed that a wide range of products of this chemical was available in local market with amalico (34.8%) being highly used. The study can conclude that the awareness of Sudanese women about this compound was poor and needs to be raised by health authorities.展开更多
Background: Melasma and post-inflammatory hyperpigmentation provide a significant source of psychosocial morbidity, especially in those with Fitzpatrick skin types III-VI. In Europe, a proprietary product aimed at tre...Background: Melasma and post-inflammatory hyperpigmentation provide a significant source of psychosocial morbidity, especially in those with Fitzpatrick skin types III-VI. In Europe, a proprietary product aimed at treating these conditions, similar to Kligman’s formula but with a longer expiry date, has become available. Objectives: To assess patient satisfaction with a newly available combination de-pigmenting preparation. Methods: We conducted a small study to see if patients felt that this new product affected their quality of life and skin symptoms from hyperpigmentation. 41 subjects, who had all been prescribed a 15 g tube to use sparingly at night for 90 days within the last 12 months were telephoned to rate the effect the cream had on their quality of life and skin symptom improvement. Each patient also had their Dermatology Life Quality Index (DLQI) score assessed. Results: Out of the 29 patients who responded to the study, 22 had melasma and 7 had post-inflammatory hyperpigmentation from acne. 21 subjects felt that the cream made either a marked or moderate improvement on their quality of life and 23 subjects felt that the cream made either a marked or moderate improvement on their skin symptoms. Conclusion: Patients reported improvement in both hyperpigmentation and quality of life, suggesting a high level of satisfaction with treatment. The long shelf life of the product may also promote compliance and reduce health-care costs.展开更多
1,4-Naphthoquinones (NQ) is a class of organic compounds with a number of important properties. However, the existing methods of their synthesis either give a low NQ yield or multistage and require a lot of time. In t...1,4-Naphthoquinones (NQ) is a class of organic compounds with a number of important properties. However, the existing methods of their synthesis either give a low NQ yield or multistage and require a lot of time. In the present work new one-pot process of NQ synthesis from hydroquinone (HQ) and substituted 1,3-dienes at room temperature is proposed. The solution of heteropolyacid H7PMo8V4O40 (HPA-4) is used as a bifunctional (acid and redox) catalyst for this process. The influence of a number of factors on key process parameters has been studied. It is demonstrated that unsubstituted and a number of alkyl substituted NQ with the yields of 50% - 80% and purity of 92% - 99% can be obtained by this method. The results obtained allow to significantly simplify the synthesis of NQ directly from HQ in comparison with the described similar methods.展开更多
Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active ca...Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co(II) could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(II) was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(II). The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃ , pH 5 and reaction time 2.5h.展开更多
In this work,the framework of Co nanoparticles and nitrogen-doped carbon nanotubes(Co/NCNTs)derived from metal-organic frameworks(MOFs)through solid pyrolysis was successfully synthesized in the atmosphere of H2 and A...In this work,the framework of Co nanoparticles and nitrogen-doped carbon nanotubes(Co/NCNTs)derived from metal-organic frameworks(MOFs)through solid pyrolysis was successfully synthesized in the atmosphere of H2 and Ar gases.The Co/NCNTs composites exhibited superior electrocatalytic performance for tert-butyl hydroquinone(TBHQ)oxidation due to the synergistic effect between chemical composition and the specific structure of Co nanoparticles and nitrogen-doped carbon nanotubes.It was found that the reaction underwent a quasi-reversible redox reaction with 37-fold higher anodic current for TBHQ at Co/NCNT-modified electrode when compared to bare glassy carbon electrode(GCE).In optimal condition,Co/NCNTs/GCE exhibited a linear range of0.05-80.00μmol·L^(-1) for detecting TBHQ,and the limit of detection(LOD)was estimated to be as low as10 nmol·L^(-1)(signal/noise of S/N=3).Moreover,the asobtained modified electrode was successfully used to assay the content of TBHQ in edible oil samples.展开更多
The title inclusion complex with the formula [(C42H70O35)2 · (C6O2H6)3 · (H2O)21.2(CH3OH)2] has been crystallized and characterized by single crystal X-ray analysis. The complex crystallizes in the triclinic...The title inclusion complex with the formula [(C42H70O35)2 · (C6O2H6)3 · (H2O)21.2(CH3OH)2] has been crystallized and characterized by single crystal X-ray analysis. The complex crystallizes in the triclinic system, space group P1, with a =1.5500 (1), b =1.5536(1), c = 1.8246(1) nm, α = 113.17(2), β = 99.12(2), γ=103.37(3)? V = 3.7739(4) nm3, Z = 1; Dc =1.343 g/cm3, μ = 0.124 mm-1, F(000) = 1594, R = 0.0795 and S = 0.9639. Two independent molecules of β-cyclodextrin (β-CD) form a 'head-to-head' dimer. The fairly important factor of the position and stability of the guest in the host cavity is the solvation of the polar group of the guest.展开更多
A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts...A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles （AuPtNPs） since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite （PG） were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy （Ea） for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts （electrodeposited on the PG） offer less activation energy （ca. 9.500 kJ mo1-1） than the bare PG （ca. 10.345 kJ mol-1）. The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.展开更多
Bis[（perfluoroalkyl）sulfonyl]imides [HN（SO2Rf）2, and Rf represents the perfluorinated alkyl group] supported on MCM-41 were synthesized and characterized by XRD, FTIR, SEM, TGA and N2-adsorption techniques. The su...Bis[（perfluoroalkyl）sulfonyl]imides [HN（SO2Rf）2, and Rf represents the perfluorinated alkyl group] supported on MCM-41 were synthesized and characterized by XRD, FTIR, SEM, TGA and N2-adsorption techniques. The supported catalysts, HN（SO2Rf）2/MCM-41, were used as the catalysts for the tert-butylafion of hydroquinone （HQ） with tert-butyl alcohol （TBA） in the liquid phase. A high yield （52.0%） of 2-tert-butyl hydroquinone （TBHQ） could be obtained in the presence of 5 tool% HN（SO2C4F9）2/MCM-41 under the optimized reaction conditions and the heterogeneous catalyst could be recycled at least 6 times without substantial loss of activity.展开更多
基金supported by the National Natural Science Foundation of China[Project No.81573192].
文摘Objective Hydroquinone(HQ),one of the phenolic metabolites of benzene,is widely recognized as an important participant in benzene-induced hematotoxicity.However,there are few relevant proteomics in HQ-induced hematotoxicity and the mechanism hasn’t been fully understood yet.Methods In this study,we treated K562 cells with 40μmol/L HQ for 72 h,examined and validated protein expression changes by Label-free proteomic analysis and Parallel reaction monitoring(PRM),and performed bioinformatics analysis to identify interaction networks.Results One hundred and eighty-seven upregulated differentially expressed proteins(DEPs)and 279 downregulated DEPs were identified in HQ-exposed K562 cells,which were involved in neutrophilmediated immunity,blood microparticle,and other GO terms,as well as the lysosome,metabolic,cell cycle,and cellular senescence-related pathways.Focusing on the 23 DEGs and 5 DEPs in erythroid differentiation-related pathways,we constructed the network of protein interactions and determined 6 DEPs(STAT1,STAT3,CASP3,KIT,STAT5B,and VEGFA)as main hub proteins with the most interactions,among which STATs made a central impact and may be potential biomarkers of HQ-induced hematotoxicity.Conclusion Our work reinforced the use of proteomics and bioinformatic approaches to advance knowledge on molecular mechanisms of HQ-induced hematotoxicity at the protein level and provide a valuable basis for further clarification.
基金This work was supported by a grant from the Major State Basic Research Development Program of China (No. 2002CB512904, 2002CB512903).
文摘Objective To explore the toxicological mechanism of hydroquinone in human bronchial epithelial cells and to investigate whether DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone. Methods DNA polymerase beta knock-down cell line was established via RNA interference as an experimental group. Normal human bronchial epithelial cells and cells transfected with the empty vector of pEGFP-C1 were used as controls. Cells were treated with different concentrations of hydroquinone （ranged from 10 μmol/L to 120 μmol/L） for 4 hours. MTT assay and Comet assay [single-cell gel electrophoresis （SCGE）] were performed respectively to detect the toxicity of hydroquinone. Results assay showed that DNA polymerase beta knock-down cells treated with different concentrations of hydroquinone had a lower absorbance value at 490 nm than the control cells in a dose-dependant manner. Comet assay revealed that different concentrations of hydroquinone caused more severe DNA damage in DNA polymerase beta knock-down cell line than in control cells and there was no significant difference in the two control groups. Conclusions Hydroquinone has significant toxicity to human bronchial epithelial cells and causes DNA damage. DNA polymerase beta knock-down cell line appears more sensitive to hydroquinone than the control cells. The results suggest that DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.
基金Supported by the National Natural Science Foundation of China(No. 20475053) and Department of Science and Technology ofJilin Province(No.20050102)
文摘The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The results show that the hydroquinone derivatives are adsorbed on a gold surface with vertical orientation, which makes the electron transfer between the bulk species and the electrode surface easier than that in the case of flat adsorption of hydroquinone derivatives that occurs at a platinum electrode. The formation of the vertical conformation and the rapid process of electron transfer were also confirmed by quantum chemistry calculations. In addition, the pre-adsorbed iodine on the electrodes played a key role on the adsorbed configuration and electron transfer of redox species.
文摘Hydroquinone(HQ)is an phenolic aromatic compound used in cosmetic medicine as skin lightening material since long time ago.Accordingly the several pathological conditions that observed,the use of HQ for this purpose was recently contraindicated.The commonly noted health problem associated with hydroquinone use was contact dermatitis.The present study was designed and conducted to determine the HQ presence and concentrations in ten samples of skin lightening cosmetics available in the local market.GC-MS analysis was employed for detection of HQ qualitatively while HPLC analysis was used as a quantitative analysis for determination of the HQ concentrations in each sample.The results obtained indicated that the overall range of HQ levels in all respected samples ranged from 0.0039%to 0.14%.
文摘Hydroquinone is potentially carcinogenic and is known to be a skin and respiratory irritant.Hydroquinone is carcinogenic it has been banned in some countries because of fears of a cancer risk[1,2].Animal studies have shown that topically applied retinoic acid can be photocarcinogenic[3].The aim of this study was qualitative and quantitative determination of hydroquinone and retinoic acid contents in facial whitening creams by colour reaction tests,FT-IR after TLC separation and HPLC.
文摘In this study, an efficient way by plasma induced mutation was applied to improve the hydroquinone degradation capacity of Serratia marcescens AB 90027 （SM27）. The results showed that combined with the selection of hydroquinone tolerance, the mutant with high hy- droquinone degradation ability induced by plasma could be achieved. The best dose for plasma mutation was 15 s, which showed a 47.0% higher positive mutation ratio. Besides, the aimed mutant was markedly different from the parent strain （SM27） in colonial traits while cultivated on Kings media. Finally, the hydroquinone degradation ratio reached 70.5~o using the induced mutant strain with 1500 mg/L hydroquinone （HQ） after 15 days of cultivation as the selective conditions; however, it was only 46.7% for SM27. The improvement of the degradation capacity by the induced mutant with a high concentration of HQ selection was attributed to its faster growth and higher hydroquinone tolerance compared with that of the parent strain.
基金supported by the Natural Science Foundation of China(No.20775060,No.20875077 and No. 20927004)the Natural Science Foundation of Gansu(No.0701RJZA109 and No.0803RJZA105)Key Projects of Scientific Research Base of Department of Education,Gansu Province(No.08zx-07)
文摘The oxidation of hydroquinone(QH_2) was investigated for the first time at liquid/liquid(L/L) interface by scanning electrochemical microscopy(SECM).In this study,electron transfer(ET) from QH_2 in aqueous to ferrocene(Fc) in nitrobenzene (NB) was probed.The apparent heterogeneous rate constants for ET reactions were obtained by fitting the experimental approach curves to the theoretical values.The results showed that the rate constants for oxidation reaction of QH_2 were sensitive to the changes of the dri...
基金This research work was financially supported by the National Natural Science Foundation of China(Grant No.20272020).
文摘First total synthesis of triprenylquinone and hydroquinones, three naturally occurringcompound 1, 2 and （±） 3, have been achieved from readily available 2-bromo-5-methyl-1,4-dimethoxybenzene 4 and geranyl bromide. The triprenylquinone and hydroquinones precursor were readily prepared with use of a Julia reaction.
文摘ENOX (ECTO-NOX) proteins are proteins of the external surface of the plasma membrane that catalyze oxidation of both NADH and hydroquinones as well as carry out protein disulfidethiol interchange. They exhibit both prion-like and time-keeping (clock) properties. The oxidative and interchange activities alternate to generate a regular period of 24 min in length. Here we report the cloning, expression, and characterization of a plant candidate constitutive ENOX (CNOX or ENOX1) protein from Arabidopsis lyrata. The gene encoding the 335 (165) amino acid protein is found in accession XP-002882467. Functional motifs characteristics of ENOX proteins previously identified by site-directed mutagenesis and present in the candidate ENOX1 protein from plants include adenine nucleotide and copper binding motifs along with essential cysteines. However, the drug binding motif (EEMTE) sequence of human ENOX2 is absent. The activities of the recombinant protein expressed in E. coli were unaffected by capsaicin, EGCg, and other ENOX2-inhibiting substances. Periodic oxidative activity was exhibited both with NAD(P)H and reduced coenzyme Q as substrate. Bound copper was necessary for activity and activity was inhibited by the ENOX1-specific inhibitor simalikalactone D. Addition of melatonin phased the 24-min period such that the next complete period began 24 min after the melatonin addition as appeared to be characteristic of ENOX1 activities in general. Periodic protein disulfide-thiol interchange activity also was demonstrated along with the 2 oxidative plus 3 interchange activity pattern characteristics of the 24-min ENOX1 protein period. Concentrated solutions of the purified plant ENOX1 protein formed insoluble aggregates, devoid of enzymatic activity, resembling amyloid. Activity was restored to aggregate preparations by isoelectric focusing.
文摘It was tried to prepare temperature and water responsive microcapsules containing hydroquinone as a water soluble core material with the spray drying method. Microcapsules were composed of ethyl cellulose (EC), methyl cellulose (MC) and P-N-isopropylacrylamid (PNIPAM). P-N-isopropylacrylamid and methyl cellulose were used as a temperature responsive polymer and as a water responsive polymer, respectively. Ethyl cellulose was the main shell material of microcapsule. At the microencapsulation process, the core and shell materials were dissolved in ethyl alcohol dissolving water (20 wt%) and then, spray-dried to prepare microcapsules. In the fundamental operation, the concentration and molecular weight of methyl cellulose were mainly changed. The releasing rate of hydroquinone was repressed at 40°C and increased at 20°C due to temperature responsive PNIPAM. Furthermore, responsibility to water was increased with the concentration of methyl cellulose.
文摘Hydroquinone (HQ) is the most important hydroxy aromatic compound which is produced on a large scale. Understanding its fate in the environment is therefore of primary importance to prevent its migration in the soil and/or the contamination of the aquatic ecosystems. Here we present a column based method to investigate the physicochemical processes controlling the removal from the aqueous phase and the adsorption onto natural quartz sand (NQS), of organic pollutant such as HQ molecules. We will focus on the interactions that occur between the organic pollutant and the NQS substrate. Thus, column reactors filled with NQS were used to investigate the influence of physicochemical parameters such as the ionic strength, the pH, the flow rate, and the nature of the electrolyte cation, on the HQ adsorption from water onto NQS substrate. The data indicate that, when divalent instead of monovalent cations, are present in the effluent water injection phase, and/or when the ionic strength of the effluent increases, the adsorbed HQ amount decreases. Similar decrease of the adsorbed HQ amount was also observed, at constant ionic strength, by increasing either, the pH from 3 to 9, the flow rate Q from 1 to 3 ml·mn-1, or by decreasing the HQ initial concentration, C0 from 30 to 6 mg·L-1. Further, large amount of the organic pollutant (up to 93 wt% of HQ molecules) was removed from the effluent water phase by using NQS column. The overall data seem to indicate that the adsorption of HQ molecules on the NQS surface is mainly controlled by electrostatic interaction forces occurring between the organic molecule polar groups and the inorganic matrix silanol groups.
文摘Hydroquinone has been used for decades as a skin lightening agent. Its use in cosmetics has been banned as a result of skin problems including contact dermatitis and ochronosis. A total of 22 samples of different skin whitening cosmetics were collected from local market. They were analyzed by using thin layer chromatography and HPLC for qualitative and quantitative determination of their hydroquinone contents. The hydroquinone was extracted from samples by using 96% ethanol and was subjected to TLC analysis. Eleven out of 22 samples were found to contain hydroquinone. The HPLC analysis showed the concentration of hydroquinone ranged from 0.002% to 0.092% in the cosmetic samples.
文摘Many countries in the world wide banned hydroquinone in cosmetics skin lightening but it is still used in most of Africa countries, including Sudan. Few studies were carried out on the side effect of hydroquinone on Sudanese women. Therefore, the present study was carried out in Khartoum state in April to May/2014 to assess the awareness of Sudanese women about using hydroquinone and its probable risks. The results revealed that, highly using cosmetics containing hydroquinone by women aged between 20 - 29 years (78.3%) as well as by those classified as single (69.6%). The results also showed that the highest percentage of women was using it during evening (81.2%) and a high percentage of them was using it for skin lightening (65.2%), followed by elimination acne (20.3%) and about 10.1% for both skin lightening and elimination of acne and very little (4.3%) for freckle elimination. Moreover, the results showed a very high percentage of women (94.2%) used the chemical without being prescribed by doctors and about (85.5%) of them didn’t know its nature and risks on human health. Consequently, (50.7%) of women have had sides effects, (44.9 %) used more than one and (44.1%) used it regularly. In addition, the results revealed that a wide range of products of this chemical was available in local market with amalico (34.8%) being highly used. The study can conclude that the awareness of Sudanese women about this compound was poor and needs to be raised by health authorities.
文摘Background: Melasma and post-inflammatory hyperpigmentation provide a significant source of psychosocial morbidity, especially in those with Fitzpatrick skin types III-VI. In Europe, a proprietary product aimed at treating these conditions, similar to Kligman’s formula but with a longer expiry date, has become available. Objectives: To assess patient satisfaction with a newly available combination de-pigmenting preparation. Methods: We conducted a small study to see if patients felt that this new product affected their quality of life and skin symptoms from hyperpigmentation. 41 subjects, who had all been prescribed a 15 g tube to use sparingly at night for 90 days within the last 12 months were telephoned to rate the effect the cream had on their quality of life and skin symptom improvement. Each patient also had their Dermatology Life Quality Index (DLQI) score assessed. Results: Out of the 29 patients who responded to the study, 22 had melasma and 7 had post-inflammatory hyperpigmentation from acne. 21 subjects felt that the cream made either a marked or moderate improvement on their quality of life and 23 subjects felt that the cream made either a marked or moderate improvement on their skin symptoms. Conclusion: Patients reported improvement in both hyperpigmentation and quality of life, suggesting a high level of satisfaction with treatment. The long shelf life of the product may also promote compliance and reduce health-care costs.
文摘1,4-Naphthoquinones (NQ) is a class of organic compounds with a number of important properties. However, the existing methods of their synthesis either give a low NQ yield or multistage and require a lot of time. In the present work new one-pot process of NQ synthesis from hydroquinone (HQ) and substituted 1,3-dienes at room temperature is proposed. The solution of heteropolyacid H7PMo8V4O40 (HPA-4) is used as a bifunctional (acid and redox) catalyst for this process. The influence of a number of factors on key process parameters has been studied. It is demonstrated that unsubstituted and a number of alkyl substituted NQ with the yields of 50% - 80% and purity of 92% - 99% can be obtained by this method. The results obtained allow to significantly simplify the synthesis of NQ directly from HQ in comparison with the described similar methods.
基金Science and Technical Department Innovation Fund and Graduate Student Innovation Project of Jiangsu Province.
文摘Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co(II) could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(II) was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(II). The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃ , pH 5 and reaction time 2.5h.
基金the National Natural Science Foundation of China(No.21904004)the Domestic Visiting Scholar Program for Outstanding Young Talents of Anhui Province(Nos.gxgnfx2019019 and gxgnfx2019020)+1 种基金the Natural Foundation of Anhui Province(No.1808085MB31)the Stable Talent Program and the Outstanding Talent Program of Anhui Science and Technology University。
文摘In this work,the framework of Co nanoparticles and nitrogen-doped carbon nanotubes(Co/NCNTs)derived from metal-organic frameworks(MOFs)through solid pyrolysis was successfully synthesized in the atmosphere of H2 and Ar gases.The Co/NCNTs composites exhibited superior electrocatalytic performance for tert-butyl hydroquinone(TBHQ)oxidation due to the synergistic effect between chemical composition and the specific structure of Co nanoparticles and nitrogen-doped carbon nanotubes.It was found that the reaction underwent a quasi-reversible redox reaction with 37-fold higher anodic current for TBHQ at Co/NCNT-modified electrode when compared to bare glassy carbon electrode(GCE).In optimal condition,Co/NCNTs/GCE exhibited a linear range of0.05-80.00μmol·L^(-1) for detecting TBHQ,and the limit of detection(LOD)was estimated to be as low as10 nmol·L^(-1)(signal/noise of S/N=3).Moreover,the asobtained modified electrode was successfully used to assay the content of TBHQ in edible oil samples.
文摘The title inclusion complex with the formula [(C42H70O35)2 · (C6O2H6)3 · (H2O)21.2(CH3OH)2] has been crystallized and characterized by single crystal X-ray analysis. The complex crystallizes in the triclinic system, space group P1, with a =1.5500 (1), b =1.5536(1), c = 1.8246(1) nm, α = 113.17(2), β = 99.12(2), γ=103.37(3)? V = 3.7739(4) nm3, Z = 1; Dc =1.343 g/cm3, μ = 0.124 mm-1, F(000) = 1594, R = 0.0795 and S = 0.9639. Two independent molecules of β-cyclodextrin (β-CD) form a 'head-to-head' dimer. The fairly important factor of the position and stability of the guest in the host cavity is the solvation of the polar group of the guest.
基金financially supported by a Research University Grant(1001/PKIMIA/811056)financial support from Universiti Sains Malaysia
文摘A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles （AuPtNPs） since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite （PG） were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy （Ea） for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts （electrodeposited on the PG） offer less activation energy （ca. 9.500 kJ mo1-1） than the bare PG （ca. 10.345 kJ mol-1）. The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.
文摘Bis[（perfluoroalkyl）sulfonyl]imides [HN（SO2Rf）2, and Rf represents the perfluorinated alkyl group] supported on MCM-41 were synthesized and characterized by XRD, FTIR, SEM, TGA and N2-adsorption techniques. The supported catalysts, HN（SO2Rf）2/MCM-41, were used as the catalysts for the tert-butylafion of hydroquinone （HQ） with tert-butyl alcohol （TBA） in the liquid phase. A high yield （52.0%） of 2-tert-butyl hydroquinone （TBHQ） could be obtained in the presence of 5 tool% HN（SO2C4F9）2/MCM-41 under the optimized reaction conditions and the heterogeneous catalyst could be recycled at least 6 times without substantial loss of activity.
