Read by QxMD icon Read

Hindered phenol

Lauréline Lecarme, Amélie Kochem, Linus Chiang, Jules Moutet, Florian Berthiol, Christian Philouze, Nicolas Leconte, Tim Storr, Fabrice Thomas
The sterically hindered bis(phenol)-dipyrrin ligandsH LH3 andPh LH3 were reacted with 1 equiv of copper(II) under ambient conditions to produce the copper radical complexes [Cu(H L)] and [Cu(Ph L)]. Their X-ray crystal structures show relatively short C-O bond distances (mean bond distances of 1.287 and 1.291 Å), reminiscent of mixed pyrrolyl-phenoxyl radical species. Complexes [Cu(H L)] and [Cu(Ph L)] exhibit rich electronic spectra, with an intense near-IR (NIR) band (ε > 6 mM-1 cm-1 ) at 1346 and 1321 nm, respectively, assigned to a ligand-to-ligand charger-transfer transition...
April 4, 2018: Inorganic Chemistry
Karthikeyan Alagarsamy, Lubobi Ferdinand Shamala, Shu Wei
Background: Camellia sinensis var. sinensis is widely grown for tea beverages that possess significant health promoting effects. Studies on tea plant genetics and breeding are hindered due to its recalcitrance to Agrobacterium -mediated genetic transformation. Among the possible reasons, oxidation of phenolics released from explant tissues and bactericidal effects of tea polyphenols during the process of transformation play a role in the plant recalcitrance. The aim of the present study was to alleviate the harmful effects of phenolic compounds using in - planta transformation...
2018: Plant Methods
Xican Li, Yulu Xie, Ke Li, Aizhi Wu, Hong Xie, Qian Guo, Penghui Xue, Yerkingul Maleshibek, Wei Zhao, Jiasong Guo, Dongfeng Chen
The study tried to explore the role of sugar-residues and mechanisms of phenolic phenylpropanoid antioxidants. Acteoside, along with its apioside forsythoside B and rhamnoside poliumoside, were comparatively investigated using various antioxidant assays. In three electron-transfer (ET)-based assays (FRAP, CUPRAC, PTIO•-scavenging at pH 4.5), the relative antioxidant levels roughly ruled as: acteoside >forsythoside B > poliumoside. Such order was also observed in H⁺-transfer-involved PTIO•-scavenging assay at pH 7...
February 23, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Muhammad Shaban, Yuhuan Miao, Abid Ullah, Anam Qadir Khan, Hakim Menghwar, Aamir Hamid Khan, Muhammad Mahmood Ahmed, Muhammad Adnan Tabassum, Longfu Zhu
Cotton, a natural fiber producing crop of huge importance for textile industry, has been reckoned as the backbone in the economy of many developing countries. Verticillium wilt caused by Verticillium dahliae reflected as the most devastating disease of cotton crop in several parts of the world. Average losses due to attack of this disease are tremendous every year. There is urgent need to develop strategies for effective control of this disease. In the last decade, progress has been made to understand the interaction between cotton-V...
February 13, 2018: Plant Physiology and Biochemistry: PPB
Paraskevi S Gerogianni, Maria V Chatziathanasiadou, Dimitrios A Diamantis, Andreas G Tzakos, Dimitrios Galaris
Phenolic acids represent abundant components contained in human diet. However, the negative charge in their carboxylic group limits their capacity to diffuse through biological membranes, thus hindering their access to cell interior. In order to promote the diffusion of rosmarinic acid through biological membranes, we synthesized several lipophilic ester- and amide-derivatives of this compound and evaluated their capacity to prevent H2O2-induced DNA damage and apoptosis in cultured human cells. Esterification of the carboxylic moiety with lipophilic groups strongly enhanced the capacity of rosmarinic acid to protect cells...
February 2, 2018: Redox Biology
Shiyu Zong, Yiqiong Pu, Suyun Li, Benliang Xu, Yong Zhang, Tong Zhang, Bing Wang
Paeonol, as the main phenolic compound isolated from the Chinese herbs, has been confirmed to present anti-inflammatory effects on ulcerative colitis (UC) in our previous study. However, its poor solubility has hindered its development of being a favourable pharmaceutical product in treating colon diseases. In this study, we prepared the colon-specific delivery system (Pae-SME-CSC) with paeonol-loaded self-microemulsion (Pae-SMEDDS), and evaluated its in vitro and in vivo properties, especially the anti-inflammatory effects on UC rats...
January 9, 2018: Artificial Cells, Nanomedicine, and Biotechnology
Fabio Aricò, Alexander S Aldoshin, Manuele Musolino, Marco Crisma, Pietro Tundo
The reactivity of β-aminocarbonates as anisotropic electrophiles has been investigated with several phenols. Products distribution shows that the regioselectivity of the anchimerically driven alkylation reaction depends on the nucleophiles. The results suggest that in the presence of nucleophiles that are also good leaving groups, the reaction takes place under thermodynamic control favoring the attack on the most sterically hindered carbon of the cyclic aziridinium intermediate. Furthermore, when an enantiomerically pure pyrrolidine-based carbonate was used, the reaction with phenols proceeds via a bicyclic aziridinium intermediate leading to the stereoselective synthesis of optically active 3-substituted piperidines via ring expansion reaction...
January 5, 2018: Journal of Organic Chemistry
Loïc P Mangin, Davit Zargarian
This report describes the results of a study on the ortho-C-H nickellation of the aryl phosphinites i-Pr2 P(OAr) derived from the following four groups of substituted phenols: 3-R-C6 H4 OH (R = F (b), Me (c), MeO (d), Cl (e)); 3,5-R2 -C6 H3 OH (R = F (f), Me (g), Cl (h), OMe (i)); 2-R-C6 H4 OH (R = Me (j), Ph(k)); and 2,6-R2 -C6 H3 OH (R = Me (l), Ph (m)). No nickellation was observed with the phosphinites derived from the 3,5-disubstituted phenols g and h, and the 2,6-disubstituted phenols l and m; in all other cases nickellation occurred at an ortho-C-H to generate either the Br-bridged dimers [{κP ,κC -(i-Pr)2 POAr}Ni(μ-Br)]2 (1b-1f, 1j, and 1k) or the monomeric acetonitrile adduct {κP ,κC -ArOP(i-Pr)2 }Ni(Br)(NCMe) (1i-NCMe)...
November 28, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Sahil Kalia, Vijay K Bharti, Arup Giri, Bhuvnesh Kumar
Extreme climatic conditions and hypobaric hypoxia at high altitude hinders the growth and productivity of chickens. The present study was carried out to examine the effect of aqueous extract of Prunus armeniaca seeds on health, survivability, antioxidants, plasma biochemical parameters, and immune status of broiler chickens at high altitude. Phytochemical analysis of extract revealed the presence of high phenolics, flavonoids, and carotenoids contents. Before the in vivo study, in vitro efficacy evaluation indicated a significant protective effect of the extract in chicken peripheral blood lymphocytes...
November 2017: Journal of Advanced Research
Mona M Khamis, Darryl J Adamko, Anas El-Aneed
Obstructive airways inflammatory diseases sometimes show overlapping symptoms that hinder their early and correct diagnosis. Current clinical tests are tedious and are of inadequate specificity in special population such as the elderly and children. Therefore, we are developing tandem mass spectrometric (MS/MS) methods for targeted analysis of urine biomarkers. Recently, proton-nuclear magnetic resonance (1 H-NMR) analysis proposed 50 urinary metabolites as potential diagnostic biomarkers among asthma and chronic obstructive pulmonary disease (COPD) patients...
October 9, 2017: Analytica Chimica Acta
Laura Cornara, Marco Biagi, Jianbo Xiao, Bruno Burlando
Honeybees produce honey, royal jelly, propolis, bee venom, bee pollen, and beeswax, which potentially benefit to humans due to the bioactives in them. Clinical standardization of these products is hindered by chemical variability depending on honeybee and botanical sources, but different molecules have been isolated and pharmacologically characterized. Major honey bioactives include phenolics, methylglyoxal, royal jelly proteins (MRJPs), and oligosaccharides. In royal jelly there are antimicrobial jelleins and royalisin peptides, MRJPs, and hydroxy-decenoic acid derivatives, notably 10-hydroxy-2-decenoic acid (10-HDA), with antimicrobial, anti-inflammatory, immunomodulatory, neuromodulatory, metabolic syndrome preventing, and anti-aging activities...
2017: Frontiers in Pharmacology
Enza Palma, Matteo Daghio, Andrea Franzetti, Marco Petrangeli Papini, Federico Aulenta
Groundwater contamination by petroleum hydrocarbons (PHs) is a widespread problem which poses serious environmental and health concerns. Recently, microbial electrochemical technologies (MET) have attracted considerable attention for remediation applications, having the potential to overcome some of the limiting factors of conventional in situ bioremediation systems. So far, field-scale application of MET has been largely hindered by the limited availability of scalable system configurations. Here, we describe the 'bioelectric well' a bioelectrochemical reactor configuration, which can be installed directly within groundwater wells and can be applied for in situ treatment of organic contaminants, such as PHs...
January 2018: Microbial Biotechnology
Parham Asgari, Udaya Sree Dakarapu, Hiep H Nguyen, Junha Jeon
Diversely substituted arylsilyl triflates, as aryne precursors for aryne cycloaddition reactions, were accessed from benzodioxasilines. Catalytic reductive C-H ortho-silylation of phenols with traceless acetal directing groups was exploited to prepare benzodioxasilines. Sequential addition of MeLi and then trifluoromethanesulfonic anhydride to benzodioxasilines provided arylsilyl triflates in a single pot. Notably, this approach was successfully utilized to prepare sterically hindered 1,2,3-trisubstituted arylsilyl triflates, which ultimately underwent fluoride-mediated aryne cycloaddition...
July 20, 2017: Tetrahedron
S R Arruda, D G Pereira, M M Silva-Castro, M G Brito, A M Waldschmidt
Some species are characterized by a high content of tannins, alkaloids, and phenols in their leaves. These secondary metabolites are released during DNA extraction and might hinder molecular studies based on PCR (polymerase chain reaction). To provide an efficient method to extract DNA, Mimosa tenuiflora, an important leguminous plant from Brazilian semiarid region used in popular medicine and as a source of fuelwood or forage, was used. Eight procedures previously reported for plants were tested and adapted from leaf tissues of M...
July 6, 2017: Genetics and Molecular Research: GMR
Jinesh C Manayil, Amin Osatiashtiani, Alvaro Mendoza, Christopher M A Parlett, Mark A Isaacs, Lee J Durndell, Chrysoula Michailof, Eleni Heracleous, Angelos Lappas, Adam F Lee, Karen Wilson
Fast pyrolysis bio-oils possess unfavorable physicochemical properties and poor stability, in large part, owing to the presence of carboxylic acids, which hinders their use as biofuels. Catalytic esterification offers an atom- and energy-efficient route to upgrade pyrolysis bio-oils. Propyl sulfonic acid (PrSO3 H) silicas are active for carboxylic acid esterification but suffer mass-transport limitations for bulky substrates. The incorporation of macropores (200 nm) enhances the activity of mesoporous SBA-15 architectures (post-functionalized by hydrothermal saline-promoted grafting) for the esterification of linear carboxylic acids, with the magnitude of the turnover frequency (TOF) enhancement increasing with carboxylic acid chain length from 5 % (C3 ) to 110 % (C12 )...
September 11, 2017: ChemSusChem
Huimin Zhang, Hai Ming, Wenfeng Zhang, Gaoping Cao, Yusheng Yang
Sodium-ion batteries (SIBs) are expected to be a promising commercial alternative to lithium-ion batteries for grid electricity storage due to their potential low cost in the near future. Up to the present, the anode material still remains a great challenge for the application of SIBs, especially at room temperature. Graphite has an obvious limitation to store larger radius sodium ions (Na(+)) in comparison with lithium ions (Li(+)), while the hard carbon with large interlayer distance can demonstrate a relatively high storage capability and durable cycle life...
July 19, 2017: ACS Applied Materials & Interfaces
Zhenchao Zhao, Hui Shi, Chuan Wan, Mary Y Hu, Yuanshuai Liu, Donghai Mei, Donald M Camaioni, Jian Zhi Hu, Johannes A Lercher
The reaction mechanism of solid-acid-catalyzed phenol alkylation with cyclohexanol and cyclohexene in the apolar solvent decalin has been studied using in situ (13)C MAS NMR spectroscopy. Phenol alkylation with cyclohexanol sets in only after a majority of cyclohexanol is dehydrated to cyclohexene. As phenol and cyclohexanol show similar adsorption strength, this strict reaction sequence is not caused by the limited access of phenol to cyclohexanol, but is due to the absence of a reactive electrophile as long as a significant fraction of cyclohexanol is present...
June 27, 2017: Journal of the American Chemical Society
Yang Liu, Natalia Oshima Nambu, Masahito Taya
Microfluidic methods are frequently used to produce cell-laden microgels for various biomedical purposes. Such microfluidic methods generally employ oil-water systems. The poor distribution of crosslinking reagents in the oil phase limits the available gelation strategies. Extracting the microgel from the oil-phase also reduces its production efficiency. In this study, an aqueous two-phase system (ATPS) involving dextran (DEX) and polyethylene glycol (PEG) was used to prepare cell-laden microgel. This avoided the problems associated with an oil phase...
September 2017: Biomedical Microdevices
Jie Han, Zhi Cao, Wei Qiu, Wei Gao, Jiangyong Hu, Baoshan Xing
The long-proposed use of open-cell polyurethane foam (PUF) as a convenient 'solid-phase extractant' for aqueous organic compounds has been hindered by a critical lack of understanding on the underlying specificity of its extraction mechanism. In this work, we tasked ourselves to understand the hierarchy of molecular structure, properties, and partitioning characteristics of compounds in PUF and aqueous phase by targeting lipophilic phenolic compounds (LPCs) as a group of primary targets for PUF extraction. Using six structurally related bisphenol analogs as comparative probes, we identified molecular lipophilicity and H-bond acidity as key molecular attributes that governed their extractability by PUF...
September 1, 2017: Talanta
Jean-Philippe R Chauvin, Evan A Haidasz, Markus Griesser, Derek A Pratt
Polysulfides are important additives to a wide variety of industrial and consumer products and figure prominently in the chemistry and biology of garlic and related medicinal plants. Although their antioxidant activity in biological contexts has received only recent attention, they have long been ascribed 'secondary antioxidant' activity in the chemical industry, where they are believed to react with the hydroperoxide products of autoxidation to slow the auto-initiation of new autoxidative chain reactions. Herein we demonstrate that the initial products of trisulfide oxidation, trisulfide-1-oxides, are surprisingly reactive 'primary antioxidants', which slow autoxidation by trapping chain-carrying peroxyl radicals...
October 1, 2016: Chemical Science
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"