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Kyung Ah Cheong, Tae Ryong Lee, Ai-Young Lee
BACKGROUND: Retinoic acid (RA) enhances skin-lightening capabilities of hydroquinone (HQ), at least in part, by facilitating desquamation which leads to increase penetration of HQ. The desquamation also affects skin irritation levels. The mechanism of RA-induced desquamation, however, has not been completely explored and no such data has been available for HQ uses. OBJECTIVE: To examine the role of HQ, RA, and their combination in the desquamation. METHODS: Primary cultured normal human keratinocytes, which were treated with HQ and/or RA in presence or absence of serine-specific inhibitor Kazal type5 (SPINK5)/lympho-epithelial Kazal-type-related inhibitor (LEKTI) knockdown or recombinant human SPINK5/LEKTI, and biopsied skin samples applied with HQ or RA were examined...
April 7, 2017: Journal of Dermatological Science
Angela van der Werf, Matic Hribersek, Nicklas Selander
A highly efficient N-trifluoromethylation of nitrosoarenes is reported. The inexpensive and convenient Langlois reagent (sodium triflinate) is employed as a CF3-radical source in combination with a copper catalyst and an oxidant. N-Trifluoromethylated hydroxylamines are obtained in high yields within 1 h at room temperature. The addition of hydroquinone was found to be instrumental to prevent the formation of side products. The method is high-yielding, is scalable, and displays a high functional group tolerance...
April 12, 2017: Organic Letters
Jing Li, Bin-Bin Gu, Fan Sun, Jian-Rong Xu, Wei-Hua Jiao, Hao-Bing Yu, Bing-Nan Han, Fan Yang, Xi-Chun Zhang, Hou-Wen Lin
Nine new sesquiterpene quinones/hydroquinones (1-7, 10, and 12), three solvent-generated artifacts (8, 9, and 11), and three known compounds, 5-epi-smenospongine (13), smenospongine (14), and smenospongiadine (15), were isolated from the marine sponge Spongia pertusa Esper. The planar structures of the new compounds were elucidated on the basis of spectroscopic analyses. Their absolute configurations were determined by comparison between the calculated and experimental ECD spectra. In the cytotoxicity bioassay, compounds 13-15 exhibited activities against the human cancer cell lines U937, HeLa, and HepG2, with most potent cytotoxicities to U937 cells with IC50 values of 2...
April 11, 2017: Journal of Natural Products
Marwa Brahem, Catherine M G C Renard, Severin Eder, Michèle Loonis, Rim Ouni, Messaoud Mars, Carine Le Bourvellec
The flesh and peel of 19 pear cultivars (8 Tunisian dessert cultivars, 8 European dessert cultivars and 3 French perry pear cultivars) were studied for their phenolic composition. Phenolic compounds were identified by HPLC/ESI-MS(2) and individually quantified by HPLC-DAD. Five classes of polyphenols were present: flavan-3-ols, phenolic acids, flavonols, anthocyanins and simple phenolics (hydroquinones). The total phenolic content ranged between 0.1g/kg Fresh Weight (FW) ('Conference' cultivar) and 8.6g/kg FW ('Plant De Blanc' cultivar) in the flesh and between 1...
May 2017: Food Research International
Murugan Velmurugan, Natarajan Karikalan, Shen-Ming Chen, Yi-Hui Cheng, Chelladurai Karuppiah
This paper describes the electrochemical preparation of highly electrochemically active and conductive activated graphene oxide (aGO). Afterwards, the electrochemical properties of aGO was studied towards the simultaneous determination of hydroquinone (HQ) and catechol (CC). This aGO is prepared by the electrochemical activation of GO by various potential treatments. The resultant aGOs are examined by various physical and electrochemical characterizations. The high potential activation (1.4 to -1.5) process results a highly active GO (aGO1), which manifest a good electrochemical behavior towards the determination of HQ and CC...
March 31, 2017: Journal of Colloid and Interface Science
M K Kureel, S R Geed, B S Giri, B N Rai, R S Singh
Benzene removal in free and immobilized cells on polyurethane foam (PUF) and polyvinyl alcohol (PVA)-alginate beads was studied using an indigenous soil bacterium Bacillus sp. M3 isolated from petroleum-contaminated soil. The important process parameters (pH, temperature and inoculums size) were optimized and found to be 7, 37°C and 6.0×10(8)CFU/mL, respectively. Benzene removals were observed to be 70, 84 and 90% within 9days in a free cell, immobilized PVA-alginate beads and PUF, respectively under optimum operating conditions...
March 30, 2017: Bioresource Technology
Maximiliano Martínez-Cifuentes, Wilson Cardona, Claudio Saitz, Boris Weiss-López, Ramiro Araya-Maturana
A theoretical exploration about hydrogen bonding in a series of synthetic regioisomeric antitumor tricyclic hydroquinones is presented. The stabilization energy for the intramolecular hydrogen bond (IHB) formation in four structurally different situations were evaluated: (a) IHB between the proton of a phenolic hydroxyl group and an ortho-carbonyl group (forming a six-membered ring); (b) between the oxygen atom of a phenolic hydroxyl group and the proton of an hydroxyalkyl group (seven membered ring); (c) between the proton of a phenolic hydroxyl group with the oxygen atom of the hydroxyl group of a hydroxyalkyl moiety (seven-membered ring); and (d) between the proton of a phenolic hydroxyl group and an oxygen atom directly bonded to the aromatic ring in ortho position (five-membered ring)...
April 7, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Hao Huang, Christoffer Karlsson, Maria Strømme, Adolf Gogoll, Martin Sjödin
We herein report the synthesis and electrochemical characterization of poly-3-((2,5-hydroquinone)vinyl)-1H-pyrrole, consisting of a polypyrrole backbone derivatized at the beta position by a vinyl-hydroquinone pendant group. The structure of the polymer was characterized by solid state NMR spectroscopy. The interactions between the polypyrrole backbone and the oxidized quinone or reduced hydroquinone pendant groups are probed by several in situ methods. In situ attenuated total reflectance-Fourier transform infrared spectroscopy shows a spectroscopic response from both the doping of the polymer backbone and the redox activity of the pendant groups...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
Martin Kuss-Petermann, Margherita Orazietti, Markus Neuburger, Peter Hamm, Oliver S Wenger
The photochemistry of a molecular pentad composed of a central anthraquinone (AQ) acceptor flanked by two Ru(bpy)3(2+) photosensitizers and two peripheral triarylamine (TAA) donors was investigated by transient IR and UV-vis spectroscopies in the presence of 0.2 M p-toluenesulfonic acid (TsOH) in deaerated acetonitrile. In ∼15% of all excited pentad molecules, AQ is converted to its hydroquinone form (AQH2) via reversible intramolecular electron transfer from the two TAA units (τ = 65 ps), followed by intermolecular proton transfer from TsOH (τ ≈ 3 ns for the first step)...
March 31, 2017: Journal of the American Chemical Society
Paula Mulo, Milagros Medina
Ferredoxin-NADP(+) reductase (FNR) catalyzes the last step of linear electron transfer in photosynthetic light reactions. The FAD cofactor of FNR accepts two electrons from two independent reduced ferredoxin molecules (Fd) in two sequential steps, first producing neutral semiquinone and then the fully anionic reduced, or hydroquinone, form of the enzyme (FNRhq). FNRhq transfers then both electrons in a single hydride transfer step to NADP(+). We are presenting the recent progress in studies focusing on Fd:FNR interaction and subsequent electron transfer processes as well as on interaction of FNR with NADP(+)/H followed by hydride transfer, both from the structural and functional point of views...
March 30, 2017: Photosynthesis Research
L L Bio, J J Cies
OBJECTIVE: To determine the presence of pregnancy warnings on over-the-counter (OTC) dermatologic products with hydroquinone, a potentially harmful ingredient. STUDY DESIGN: Data were obtained from the Food and Drug Administration National Drug Code Directory and Label Repository to identify OTC dermatologic products containing hydroquinone. Products were stratified based on pregnancy or general warning presence (WP) or absence (WA). Product characteristics were compared between groups: hydroquinone concentration, presence of external packaging, indication and warning statements...
March 30, 2017: Journal of Perinatology: Official Journal of the California Perinatal Association
Sergio Gutiérrez, Alfredo Morán, Honorina Martínez-Blanco, Miguel A Ferrero, Leandro B Rodríguez-Aparicio
The effect of generally recognised as safe (GRAS) plant metabolites in regulating the growth of human pathogenic and probiotic bacteria and in the formation of biofilm was investigated. Thymol, carvacrol and eugenol showed the strongest antibacterial action against both pathogenic and probiotic microorganisms, at a subinhibitory concentration (SIC) of ≤50 μg ml(-1). Genistein, hydroquinone, p-hydroxybenzoic acid and resveratrol also showed antibacterial effects but at a wide concentration range (SIC = 50-1000 μg ml(-1))...
March 29, 2017: Probiotics and Antimicrobial Proteins
Shangjun Meng, Ying Hong, Ziyang Dai, Wei Huang, Xiaochen Dong
Herein, ZnO nanorods with an average diameter of 50 nm were uniformly anchored on the surface of carbon cloth directly by a simple hydrothermal method. The nanorods growing in situ along the specific direction of (002) have single-crystalline features and a columnar structure. On the basis of the ZnO nanorod/carbon cloth composite, free-standing electrodes were fabricated for the simultaneous determination of dihydroxybenzene isomers. The ZnO nanorod/carbon cloth electrodes exhibited excellent electrochemical stability, high sensitivity, and high selectivity...
April 3, 2017: ACS Applied Materials & Interfaces
David P Walton, Dennis A Dougherty
Visible-light triggered quinone trimethyl locks are reported as a general design for long-wavelength photoremovable protecting groups for alcohols and amines. Intramolecular photoreduction unmasks a reactive phenol that undergoes fast lactonization to release alcohols and amines. Model substrates are released in quantitative yield along with well-defined, colorless hydroquinone byproducts. Substituent modifications of the quinone core allow absorption from 400 to 600 nm.
March 24, 2017: Journal of the American Chemical Society
Shi-Xia Huo, Qiong Wang, Xin-Min Liu, Chun-Hui Ge, Li Gao, Xiao-Ming Peng, Ming Yan
Vernonia anthelmintica (L.) Willd has been traditionally used in the treatment of vitiligo in Uyghur medicine. This study used butin, the main component of V. anthelmintica, to study the influence on hydroquinone-induced vitiligo in mice. The animals were randomly divided into six groups: control, model, 8-methoxypsoralen (8-MOP, 4.25 mg/kg), and butin (0.425, 4.25, and 42.5 mg/kg) groups. The number of melanin-containing hair follicles, basal layer melanocytes, melanin-containing epidermal cells, the expression of tyrosinase (TYR) and tyrosinase-related protein-1 (TRP-1), the malondialdehyde (MDA), and cholinesterase (CHE) activity in serum were measured...
March 21, 2017: Phytotherapy Research: PTR
Pearl E Grimes, Rama Nashawati
The general goals of medical management of vitiligo are to repigment vitiliginous areas of skin and to stabilize the progression of depigmentation. However, for some patients with vitiligo affecting extensive body surface areas who are unresponsive to repigmentation therapies, depigmentation of the remaining normal skin may be a better choice. Candidates for depigmentation therapy should be carefully screened and patient education is essential. Permanent topical therapies used for depigmentation include monobenzyl ether of hydroquinone, 4-methoxyphenol, and 88% phenol...
April 2017: Dermatologic Clinics
Rikard Emanuelsson, Mia Sterby, Maria Strømme, Martin Sjödin
Rechargeable batteries that use organic matter as the capacity-carrying material have previously been considered a technology for the future. Earlier batteries in which both the anode and cathode consisted of organic material required significant amounts of conductive additives and were often based on metal-ion electrolytes containing Li(+) or Na(+). However, we have used conducting poly(3,4-ethylenedioxythiophene) (PEDOT), functionalized with anthraquinone (PEDOT-AQ) or benzonquinone (PEDOT-BQ) pendant groups as the negative and positive electrode materials, respectively, to make an all-organic proton battery devoid of metals...
March 28, 2017: Journal of the American Chemical Society
Shi-Xin Fa, Xu-Dong Wang, Qi-Qiang Wang, Yu-Fei Ao, De-Xian Wang, Mei-Xiang Wang
Biomimicry of multiresponsive recognition of cell membrane with artificial membranes is challengeable. In this work, we designed azacalix[4]pyridine-based amphiphilic molecules 1 and 2. The self-assembly behaviors of 1 and 2 were investigated in aqueous medium. As demonstrated by DLS, SEM, TEM, and LSCM measurements, 1 formed stable vesicles (size 322 nm) in a mixture of THF/water, whereas 2 produced giant vesicles with decreased stability (size 928 nm). The vesicles composed of 1, with surface being engineered with the cavities of azacalix[4]pyridines, showed selective responses to a variety of guests including zinc ion, hydroquinone, and proton as monitored by DLS...
March 29, 2017: ACS Applied Materials & Interfaces
Marina Perper, Ariel Eva Eber, Rachel Fayne, Sebastian Hugo Verne, Robert James Magno, Jessica Cervantes, Mana ALharbi, Ibrahim ALOmair, Abdulkarem Alfuraih, Keyvan Nouri
Melasma is a common acquired pigmentary disorder marked by irregular hyperpigmented macules or patches and most commonly occurs in women of darker skin color. It is a chronic often-relapsing condition that causes negative psychosocial effects in those affected. Current treatments such as hydroquinone, kojic acid, and retinoids, among others, demonstrate variable efficacy and side-effect profiles. We conducted a comprehensive literature review examining the use of tranexamic acid (TA), a well-known anti-fibrinolytic agent, in the treatment of melasma...
March 10, 2017: American Journal of Clinical Dermatology
Maxim V Ivanov, Vincent J Chebny, Marat R Talipov, Rajendra Rathore
Typical poly-p-phenylene wires are characterized by strong interchromophoric electronic coupling with redox and optical properties being highly length-dependent. Herein we show that an incorporation of a pair of para-methoxy groups at each p-phenylene unit in poly-p-phenylene wires (i.e., PHEn) changes the nodal structure of HOMO that leads to length-invariant oxidation potentials and cation radical excitation energies. As such, PHEn represents a unique class of isoenergetic wires where hole delocalization mainly occurs via dynamic hopping and thus may serve as an efficient medium for long-range charge transfer...
March 16, 2017: Journal of the American Chemical Society
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