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Harini R Bala, Senhong Lee, Celestine Wong, Amit G Pandya, Michelle Rodrigues
BACKGROUND: Melasma is a common acquired disorder of hyperpigmentation that commonly affects those with skin of color. Tranexamic acid (TXA) is a novel treatment for melasma that has a multimodal mechanism of action. OBJECTIVE: To provide a comprehensive review of the literature regarding the evidence on the mode of action, safety profile, and efficacy of TXA in the treatment of melasma. MATERIALS AND METHODS: The literature was searched for publications on TXA in the treatment of melasma using MEDLINE, Scopus, and Google Scholar...
April 19, 2018: Dermatologic Surgery: Official Publication for American Society for Dermatologic Surgery [et Al.]
Hailong Wang, Quanqin Hu, Yuan Meng, Zier Jin, Zilin Fang, Qinrui Fu, Wenhua Gao, Liang Xu, Yibing Song, Fushen Lu
Reduced graphite oxide (rGO) was incorporated into a metal organic framework (MOF) MIL-101(Cr) for the modification of carbon paste electrode. Taking advantages of the large surface area of MOF and the electrical conductivity of rGO, the resulted electrodes exhibited high sensitivity and reliability in the simultaneous electrochemical identification and quantification of catechol (CC) and hydroquinone (HQ). Specifically, in the mixture solution of catechol and hydroquinone (constant concentration of an analyte), the linear response ranges for catechol and hydroquinone were 10-1400 μM and 4-1000 μM, and detection limits were 4 μM and 0...
February 19, 2018: Journal of Hazardous Materials
Monique J Vanaman Wilson, Isabela T Jones, Joanna Bolton, Lisa Larsen, Sabrina Guillen Fabi
BACKGROUND: The nonablative, fractional, 1,927-nm diode laser is theoretically a safe and effective treatment for hyperpigmentation and melasma in darker skin and may potentiate topical cosmeceutical delivery. OBJECTIVE: To evaluate the use of a nonablative, fractional, 1,927-nm diode laser with and without topical 2% hydroquinone (HQ) cream for moderate-to-severe facial hyperpigmentation in Fitzpatrick skin Types III-V. METHODS: Forty adults underwent 4 laser treatments at 2-week intervals and were randomized to daily application of 2% HQ cream or moisturizer...
April 13, 2018: Dermatologic Surgery: Official Publication for American Society for Dermatologic Surgery [et Al.]
Sajad Ahmad Bhat, Nusrat Rashid, Mudasir Ahmad Rather, Sarwar Ahmad Pandit, Ghulam Mohammad Rather, Pravin P Ingole, Mohsin Ahmad Bhat
The recent reports about the promising and tuneable electrocatalytic activity and stability of nanoalloys have stimulated an intense research activity towards the design and synthesis of homogenously alloyed novel bimetallic nano-electrocatalysts. We, herein present a simple one-pot facile wet-chemical approach for the deposition of high quality bimetallic palladium-silver (PdAg) homogenous nanoalloy crystals on reduced graphene oxide (Gr) sheets. Morphological, structural and chemical characterization of the so crafted nanohybrids establishes a homogeneous distribution of 1:1 PdAg nanoalloy crystals supported over reduced graphene oxide (PdAg-Gr)...
April 16, 2018: ACS Applied Materials & Interfaces
In Sub Shin, Yuta Shimada, Emi Horiguchi-Babamoto, Shinya Matsumoto
We obtained two conformational polymorphs of 2,5-dichloro-3,6-bis(dibenzylamino)-p-hydroquinone, C34 H30 Cl2 N2 O2 . Both polymorphs have an inversion centre at the centre of the hydroquinone ring (Z' = 1/2), and there are no significant differences between their bond lengths and angles. The most significant structural difference in the molecular conformations was found in the rotation of the phenyl rings of the two crystallographically independent benzyl groups. The crystal structures of the polymorphs were distinguishable with respect to the arrangement of the hydroquinone rings and the packing motif of the phenyl rings that form part of the benzyl groups...
April 1, 2018: Acta Crystallographica. Section C, Structural Chemistry
Liang Yu, Shaozhong Zeng, Xierong Zeng, Xiaohua Li, Hongliang Wu, Yuechao Yao, Wenxuan Tu, Jizhao Zou
Facile synthesis of carbon materials with high heteroatom content, large specific surface area (SSA) and hierarchical porous structure is critical for energy storage applications. In this study, nitrogen and oxygen co-doped clews of carbon nanobelts (NCNBs) with hierarchical porous structures are successfully prepared by a carbonization and subsequent activation by using ladder polymer of hydroquinone and formaldehyde (LPHF) as the precursor and ammonia as the activating agent. The hierarchical porous structures and ultra-high SSA (up to 2994 m² g−1 ) can effectively facilitate the exchange and transportation of electrons and ions...
April 4, 2018: Materials
Adriana R Kyvik, Carlos Luque-Corredera, Daniel Pulido, Miriam Royo, Jaume Veciana, Judith Guasch, Imma Ratera
Stimuli-responsive self-assembled monolayers (SAMs) are used to confer switchable physical, chemical, or biological properties to surfaces through the application of external stimuli. To obtain spatially and temporally tunable surfaces, we present microcontact printed SAMs of an hydroquinone molecule that are used as a dynamic interface to immobilize different functional molecules either via Diels Alder or Michael thiol addition reactions upon the application of a low potential. In spite of the use of such reactions and the potential applicability of the resulting surfaces in different fields ranging from sensing to biomedicine through data storage or clean up, a direct comparison of the two functionalization strategies on a surface has not yet been performed...
April 4, 2018: Journal of Physical Chemistry. B
Chee-Leok Goh, Sai Yee Chuah, Steven Tien, Guan Thng, María Alejandra Vitale, Arancha Delgado-Rubin
Introduction: Melasma is a common pigmentary disorder with a multifactorial etiology that can hinder its management. The aqueous extract of the fern Polypodium leucotomos (PLE), Fernblock® (IFC, Madrid, Spain), has demonstrated antioxidant and photoprotective activities and has been used for the treatment of several pigmentary disorders. The aim of this study was to evaluate the efficacy and safety of oral PLE in the treatment of melasma in Asian patients. Methods: Forty healthy adult patients with clinical diagnoses of melasma who were receiving treatment with topical 4% hydroquinone cream and sunscreen with a sun protection factor (SPF) of 50+ were recruited for inclusion in this study from the National Skin Centre in Singapore...
March 2018: Journal of Clinical and Aesthetic Dermatology
Zhen Li, Yuhua Yue, Yanjun Hao, Shun Feng, Xianli Zhou
A nafion film containing cerium phosphate nanotubes was pasted onto a glassy carbon electrode (GCE) to obtain a sensor for hydroquinone (HQ). The morphologies and components of the coating were characterized by transmission electron microscopy, scanning electron microscopy and energy-dispersive spectroscopy. Cyclic voltammetry and differential pulse voltammetry (DPV) showed the specific surface of the electrode to be significantly increased and the electron transfer rate to be accelerated. The modified GCE was applied to the determination of hydroquinone (HQ) via DPV...
March 12, 2018: Mikrochimica Acta
Nasrin Siraj Lopa, Md Mahbubur Rahman, Hohyoun Jang, Sabuj Chandra Sutradhar, Faiz Ahmed, Taewook Ryu, Whangi Kim
2,4-Dinitrophenylhydrazine (DNPH) was electropolymerized on the surface of an anodized glassy carbon electrode by cyclic voltammetry. The anodized electrode has a highly electroactive surface due to the creation of chemically functionalized graphitic nanoparticles, and this facilitates the formation of poly-DNPH via radical polymerization. Poly-DNPH displays excellent redox activity due to the presence of nitro groups on its backbone. These catalyze the electro-oxidation of hydroquinone (HQ) and catechol (CT)...
December 6, 2017: Mikrochimica Acta
Juan Tang, Yapei Huang, Yu Cheng, Lulu Huang, Junyang Zhuang, Dianping Tang
Two-dimensional (2D) MoS2 is found to possess different affinities for ssDNA and dsDNA. This finding is exploited in an amperometric aptamer-based method for the determination of the mycotoxin ochratoxin A (OTA). Initially, a dsDNA probe (formatted through the hybridization of OTA-aptamer with an auxiliary DNA) is self-assembled on a gold electrode. Upon introduction of OTA, it will bind to the aptamer and cause the unwinding of dsDNA, while the auxiliary DNA (with single-stranded structure) remains on the electrode...
February 7, 2018: Mikrochimica Acta
Lorena Athie Goulart, Roger Gonçalves, Alessandra Alves Correa, Ernesto Chaves Pereira, Lucia Helena Mascaro
A glassy carbon electrode (GCE) was modified with multi-walled carbon nanotubes (MWCNT) and silver nanoparticles (AgNPs) and applied to the simultaneous determination of hydroquinone (HQ), catechol (CC), bisphenol A (BPA) and phenol by using square-wave voltammetry. The MWCNTs were deposited on the GCE and the AgNPs were then electrodeposited onto the MWCNT/GCE by the application of 10 potential sweep cycles using an AgNP colloidal suspension. The modified GCE was characterized by using SEM, which confirmed the presence of the AgNPs...
December 5, 2017: Mikrochimica Acta
Wei Huang, Ting Zhang, Xiaoya Hu, Yang Wang, Jianmin Wang
A porous carbon material doped with an iron species (Fe/PC) was prepared by carbonizing a mixture of zeolitic imidazolate framework-8 in the presence of iron(II) ions. The resulting material was characterized by X-ray diffraction, nitrogen adsorption isotherms, transmission electron microscopy, and by Raman and X-ray photoelectron spectroscopy. Fe/PC was the deposited on the surface of glassy carbon electrode (GCE) to obtain a sensor for amperometric determination of phenolic compounds. The unique catalytic activity, good electrical conductivity and hierarchical structure of the Fe/PC composite results in good electrooxidative activity towards hydroquinone (HQ; typically at 44 mV) and catechol (CC; typically at 160 mV)...
December 7, 2017: Mikrochimica Acta
Mark A Rishavy, Kevin W Hallgren, Lee Wilson, Savita Singh, Kurt W Runge, Kathleen L Berkner
The anticoagulant warfarin inhibits the vitamin K oxidoreductase (VKORC1), which generates vitamin K hydroquinone (KH2 ) required for the carboxylation and consequent activation of vitamin K-dependent (VKD) proteins. VKORC1 produces KH2 in two reactions: reduction of vitamin K epoxide (KO) to quinone (K) and then KH2 , and our dissection of full reduction versus the individual reactions revealed a surprising mechanism of warfarin inhibition. Warfarin inhibition of KO to K reduction and carboxylation that requires full reduction were compared in wild type VKORC1 or mutants (Y139H, Y139F) that cause warfarin resistance...
March 28, 2018: Blood
Chen Ling, Cai-Liang Yue, Fu-Qiang Liu, Meng-Meng Wei, Tai-Peng Chen, Jun-Jie Zhu
Coadsorption of Cu(II) and two dihydroxybenzene isomers (hydroquinone, HQ and catechol, CAT) onto a multi-amine modified resin (CEAD) were comparatively studied. The presence of Cu(II) promoted adsorption of both HQ and CAT by a maximum of 25.8% and 41.6%, respectively. However, two diphenols exerted a very different influence on Cu(II) uptake. Higher concentrations of HQ consistently suppressed Cu(II) adsorption while the coexistence of CAT facilitated it, especially at lower CAT concentrations. The interactions among solutes and adsorbents were revealed by means of kinetic tracking, sequential adsorption experiments, and characterizations/calculations (FTIR, XPS, MINTEQ and DFT)...
March 15, 2018: Journal of Hazardous Materials
Oh Sung Kwean, Su Yeon Cho, Jun Won Yang, Wooyoun Cho, Sungyoon Park, Yejee Lim, Min Chul Shin, Han-Suk Kim, Joonhong Park, Han S Kim
A biodegradation facilitator which catalyzes the initial steps of 4-chlorophenol (4-CP) oxidation was prepared by immobilizing multiple enzymes (monooxygenase, CphC-I and dioxygenase, CphA-I) onto a natural inorganic support. The enzymes were obtained via overexpression and purification after cloning the corresponding genes (cphC-I and cphA-I) from Arthrobacter chlorophenolicus A6. Then, the recombinant CphC-I was immobilized onto fulvic acid-activated montmorillonite. The immobilization yield was 60%, and the high enzyme activity (82...
March 16, 2018: Bioresource Technology
Faik Gökalp
The natural antioxidants of olive oil have phenolic structure and their activities are related to the formation of stable derivatives. In this study, the single components of the phenolic fraction of olive oil (1,4-hydroquinone, Semiquinone and 1,4-benzoquinone) have been studied as theoretical by using DFT (Density functional Theory). The behaviors of phenolic compounds of olive against to the alkyl peroxy radicals were investigated. Our data show that 1,4-benzoquinone is the best electron transfer agent in primary metabolic processes to human life...
April 2018: Journal of Food and Drug Analysis
Se Eun Byeon, Young-Su Yi, Jongsung Lee, Woo Seok Yang, Ji Hye Kim, Jooyoung Kim, Suntaek Hong, Jong-Hoon Kim, Jae Youl Cho
Hydroquinone (HQ, 1,4-benzenediol) is a hydroxylated benzene metabolite with various biological activities, including anti-oxidative, neuroprotective, immunomodulatory, and anti-inflammatory functions. However, the anti-cancer activity of HQ is not well understood. In this study, the in vitro and in vivo anti-cancer activity of HQ was investigated in various cancer cells and tumor-bearing mouse models. HQ significantly induced the death of A431, SYF, B16F10, and MDA-MB-231 cells and also showed a synergistic effect on A431 cell death with other anti-cancer agents, such as adenosine-2',3'-dialdehyde and buthionine sulfoximine...
March 19, 2018: International Journal of Molecular Sciences
Peng Lin, Chen Xu, Wei Xing, Luni Sun, Daniel I Kaplan, Nobuhide Fujitake, Chris M Yeager, Kathleen A Schwehr, Peter H Santschi
Uptake of six particle-reactive and/or redox-sensitive radionuclides (210 Pb,234 Th,7 Be,59 Fe,237 Np and233 Pa) by 14 humic acids (HAs) was investigated in artificial groundwater under mildly acidic conditions (pH~5.5). In HA-groundwater slurry, Pb, Be, Fe and Pa bound strongly to particulate HA (>0.45 µm), supporting their application as tracers of soil erosion. Th bound strongly to the colloidal HA (3 kDa-0.45 µm) and as such, would not be a good candidate as a tracer for monitoring soil erosion...
March 19, 2018: Scientific Reports
Ji-Yuan Zhang, Xiao-Rui Fan, Xiao-Qian Liu, Xiao-Wei Yu, Li-Xin Yang, Zhi-Ting Guo, Wei-Hong Feng, Zhi-Min Wang, Chun Li
A quantitative nuclear magnetic resonance method(qNMR) was established for determination of the absolute content of febrifugine. Proton nuclear magnetic resonance spectroscopy of febrifugine was obtained in DMSO-d₆ with hydroquinone as the internal standard substance on a Bruker Ascend 600 MHz superconducting nuclear resonance spectrometer at 298 K. The specific parameters were as follows: the observing frequency was 600 MHz,spectra width was 7 211 Hz, pulse width was 9.70 μs, pulse sequence was zg30,scan times was 32 and relaxation time was 2 s...
January 2018: Zhongguo Zhong Yao za Zhi, Zhongguo Zhongyao Zazhi, China Journal of Chinese Materia Medica
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