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heterocyclic amines

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https://www.readbyqxmd.com/read/28205448/association-between-red-meat-consumption-and-colon-cancer-a-systematic-review-of-experimental-results
#1
Nancy D Turner, Shannon K Lloyd
A role for red and processed meat in the development of colorectal cancer has been proposed based largely on evidence from observational studies in humans, especially in those populations consuming a westernized diet. Determination of causation specifically by red or processed meat is contingent upon identification of plausible mechanisms that lead to colorectal cancer. We conducted a systematic review of the available evidence to determine the availability of plausible mechanistic data linking red and processed meat consumption to colorectal cancer risk...
January 1, 2017: Experimental Biology and Medicine
https://www.readbyqxmd.com/read/28205441/access-to-aminated-saturated-oxygen-heterocycles-via-copper-catalyzed-aminooxygenation-of-alkenes
#2
Jian Xie, Yue-Wei Wang, Lian-Wen Qi, Bo Zhang
A copper-catalyzed aminooxygenation of unactivated alkenes with various O-nucleophiles is described. This novel methodology uses commercially available N-fluorobenzenesulfonimide as an amination reagent and provides a simple and efficient approach to a wide range of aminated saturated oxygen heterocycles in moderate to good yields. The reaction features mild reaction conditions, operational simplicity, and a broad substrate scope.
February 16, 2017: Organic Letters
https://www.readbyqxmd.com/read/28197734/non-canonical-amino-acids-bearing-thiophene-and-bithiophene-synthesis-by-an-ugi-multicomponent-reaction-and-studies-on-ion-recognition-ability
#3
Cátia I C Esteves, M Manuela M Raposo, Susana P G Costa
Novel thienyl and bithienyl amino acids with different substituents were obtained by a multicomponent Ugi reaction between a heterocyclic aldehyde, an amine, an acid and an isocyanide. Due to the presence of the sulphur heterocycle at the side chain, these unnatural amino acids are highly emissive and bear extra electron donating atoms so they were tested for their ability to act as fluorescent probes and chemosensors in the recognition of biomedically relevant ions in acetonitrile and acetonitrile/water solutions...
February 14, 2017: Amino Acids
https://www.readbyqxmd.com/read/28188647/formation-of-heterocyclic-amines-in-chinese-marinated-meat-effects-of-animal-species-and-ingredients-rock-candy-soy-sauce-and-rice-wine
#4
Pan Wang, Yanting Hong, Weixin Ke, Xiaosong Hu, Fang Chen
BACKGROUND: Heterocyclic aromatic amines (HAAs) are one type of neo-formed contaminants in protein-rich foods during heat processing. Recently, accumulative studies have focused on the formation of HAs in Western foods. However, there is little knowledge about the occurrence of HAAs in traditional Chinese foods. The objective of this study was to determinate the contents of main HAs in traditional marinated meat products by UPLC-MS/MS, and to investigate the effects of animal species and the ingredients (soy sauce, rock candy, and rice wine) on the formation of HAAs in marinated meats...
February 11, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/28169167/design-and-synthesis-of-a-novel-series-of-4-heteroarylamino-1-azaspiro-oxazole-5-3-bicyclo-2-2-2-octanes-as-%C3%AE-7-nicotinic-receptor-agonists-2-development-of-4-heteroaryl-sar
#5
Christiana Iwuagwu, Dalton King, Ivar M McDonald, James Cook, F Christopher Zusi, Matthew D Hill, Robert A Mate, Haiquan Fang, Ronald Knox, Lizbeth Gallagher, Debra Post-Munson Amy Easton, Regina Miller, Yulia Benitex, Judy Siuciak, Nicholas Lodge, Robert Zaczek, Daniel Morgan, Linda Bristow, John E Macor, Richard E Olson
Quinuclidine-containing spirooxazolines, as described in the previous report in this series, were demonstrated to have utility as α7 nicotinic acetylcholine receptor (α7 nAChR) partial agonists. In this work, the SAR of this chemotype was expanded to include an array of diazine heterocyclic substitutions. Many of the heterocyclic analogs were potent partial agonists of the α7 receptor, selective against other nicotinic receptors and the serotinergic 5HT3A receptor. (1'S,3'R,4'S)-N-(6-phenylpyrimidin-4-yl)-4H-1'-azaspiro[oxazole-5,3'-bicyclo[2...
January 20, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28163803/estrogen-and-stress-induced-dna-damage-in-breast-cancer-and-chemoprevention-with-dietary-flavonoid
#6
REVIEW
Michiko T Yasuda, Hiroyuki Sakakibara, Kayoko Shimoi
Breast cancer is one of the most commonly diagnosed female cancers and a leading cause of cancer-related death in women. Multiple factors are responsible for breast cancer and heritable factors have received much attention. DNA damage in breast cancer is induced by prolonged exposure to estrogens, such as 17β-estradiol, daily social/psychological stressors, and environmental chemicals such as polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs). DNA damage induced by estrogen and stress is an important factor in the pathogenesis and development of breast cancer and is now recognized as a critical provision for chemoprevention of breast cancer...
2017: Genes and Environment: the Official Journal of the Japanese Environmental Mutagen Society
https://www.readbyqxmd.com/read/28160022/role-of-human-sulfotransferase-1a1-and-n-acetyltransferase-2-in-the-metabolic-activation-of-16-heterocyclic-amines-and-related-heterocyclics-to-genotoxicants-in-recombinant-v79-cells
#7
Matthieu Chevereau, Hansruedi Glatt, Daniel Zalko, Jean-Pierre Cravedi, Marc Audebert
Heterocyclic aromatic amines (HAAs) are primarily produced during the heating of meat or fish. HAAs are mutagenic and carcinogenic, and their toxicity in model systems depend on metabolic activation. This activation is mediated by cytochrome P450 (CYP) enzymes, in particular CYP1A2. Some studies have indicated a role of human sulfotransferase (SULT) 1A1 and N-acetyltransferase (NAT) 2 in the terminal activation of HAAs. In this study, we conducted a metabolism/genotoxicity relationship analysis for 16 HAAs and related heterocyclics...
February 3, 2017: Archives of Toxicology
https://www.readbyqxmd.com/read/28149955/lewis-acid-induced-toggle-from-ir-ii-to-ir-iv-pathways-in-photocatalytic-reactions-synthesis-of-thiomorpholines-and-thiazepanes-from-aldehydes-and-slap-reagents
#8
Sheng-Ying Hsieh, Jeffrey W Bode
Redox neutral photocatalytic transformations often require careful pairing of the substrates and photoredox catalysts in order to achieve a catalytic cycle. This can limit the range of viable transformations, as we recently observed in attempting to extend the scope of the photocatalytic synthesis of N-heterocycles using silicon amine protocol (SLAP) reagents to include starting materials that require higher oxidation potentials. We now report that the inclusion of Lewis acids in photocatalytic reactions of organosilanes allows access to a distinct reaction pathway featuring an Ir(III)*/Ir(IV) couple instead of the previously employed Ir(III)*/Ir(II) pathway, enabling the transformation of aromatic and aliphatic aldehydes to thiomorpholines and thiazepanes...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28145410/photo-induced-oxidant-free-oxidative-c-h-n-h-cross-coupling-between-arenes-and-azoles
#9
Linbin Niu, Hong Yi, Shengchun Wang, Tianyi Liu, Jiamei Liu, Aiwen Lei
Direct cross-coupling between simple arenes and heterocyclic amines under mild conditions is undoubtedly important for C-N bonds construction. Selective C(sp(2))-H amination is more valuable. Herein we show a selective C(sp(2))-H amination of arenes (alkyl-substituted benzenes, biphenyl and anisole derivatives) accompanied by hydrogen evolution by using heterocyclic azoles as nitrogen sources. The reaction is selective for C(sp(2))-H bonds, providing a mild route to N-arylazoles. The KIE (kinetic isotope effect) experiment reveals the cleavage of C-H bond is not involved in the rate-determining step...
February 1, 2017: Nature Communications
https://www.readbyqxmd.com/read/28139123/biomonitoring-dna-adducts-of-cooked-meat-carcinogens-in-human-prostate-by-nano-liquid-chromatography-high-resolution-tandem-mass-spectrometry-identification-of-2-amino-1-methyl-6-phenylimidazo-4-5-b-pyridine-dna-adduct
#10
Shun Xiao, Jingshu Guo, Byeong Hwa Yun, Peter W Villalta, Suprita Krishna, Resha Tejpaul, Paari Murugan, Christopher J Weight, Robert J Turesky
Epidemiologic studies have reported an association between frequent consumption of well-done cooked meats and prostate cancer risk. However, unambiguous physiochemical markers of DNA damage from carcinogens derived from cooked meats, such as DNA adducts, have not been identified in human samples to support this paradigm. We have developed a highly sensitive nano-LC-Orbitrap MS (n) method to measure DNA adducts of several carcinogens originating from well-done cooked meats, tobacco smoke, and environmental pollution, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), benzo[a]pyrene (B[a]P), and 4-aminobiphenyl (4-ABP)...
December 20, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/28137605/protection-against-neo-formed-contaminants-nfcs-induced-toxicity-by-phytochemicals
#11
Mengyao Zhao, Pengpu Wang, Daotong Li, Jin Shang, Xiaosong Hu, Fang Chen
Neo-formed compounds (NFCs) are commonly found in all kinds of foods due to the complex reaction between components during processing. Acrylamide, benzo(a)pyrene and heterocyclic aromatic amines are the main types of NFCs in foods enriched with carbohydrate, fats and proteins, respectively. They have exhibited diverse toxicity, such as neurotoxicity, genotoxicity, potentially carcinogenic and reproductive toxicity. In recent years, various phytochemicals have been found to be effective in alleviation of their related toxicities both in vitro and in vivo...
January 28, 2017: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/28133657/n-n-bond-formation-in-ugi-processes-from-nitric-acid-to-libraries-of-nitramines
#12
Valentina Mercalli, Aude Nyadanu, Marie Cordier, Gian Cesare Tron, Laurence Grimaud, Laurent El Kaim
The Ugi reaction has drawn considerable attention over the years leading to numerous libraries of heterocycles and various extensions changing the nature of the components of the coupling. We report here the use of nitric acid as carboxylic acids surrogates, displaying the first aminative Ugi-type reaction leading to nitramines.
February 9, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28128923/base-mediated-hydroamination-of-alkynes
#13
Monika Patel, Rakesh K Saunthwal, Akhilesh K Verma
Inter- or intramolecular hydroamination reactions are a paradigmatic example of modern sustainable organic chemistry, as they are a catalytic, 100% atom-economical, and waste-free process of fundamental simplicity in which an amine is added to an alkyne substrate. Many enamines are found in many natural and synthetic compounds possessing interesting physiological and biological activities. The development of synthetic protocols for such molecules and their transformation is a persistent research topic in pharmaceutical and organic chemistry...
January 27, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28127598/iterative-direct-c-sp-3-h-functionalization-of-amines-diastereoselective-divergent-syntheses-of-%C3%AE-%C3%AE-disubstituted-alicyclic-amines
#14
Sujit Mahato, Chandan K Jana
A novel iterative C(sp(3))-H oxygenation/C-C bond formation strategy, which avoids repetitive N-protection/-deprotection steps, was developed for direct α,α'-difunctionalization of alicyclic amines. The method is highly efficient and stereoselective in producing syn-α,α'-disubstituted aliphatic N-heterocycles. Synthetic potential and practicability of the method was demonstrated by an easy and straightforward synthesis of neuroactive alkaloid nor-lobelane and its derivatives.
January 27, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28125103/n-formylation-and-n-methylation-of-amines-using-metal-free-n-heterocyclic-carbene-catalysts-and-co2-as-carbon-source
#15
Felix D Bobbink, Shoubhik Das, Paul J Dyson
N-formylation and N-methylation of amines are important reactions that are used to produce a wide range of key intermediates and compounds. This protocol describes the environmentally benign N-formylation and N-methylation of primary and secondary amines using carbon dioxide (CO2) as the carbon source, hydrosilanes as reductants and N-heterocyclic carbenes (NHCs) as catalysts. Using CO2 as a reagent has the advantage of low cost and negligible toxicity. However, the catalyst is air-sensitive and must be generated fresh before use; consequently, the techniques used to prepare and manipulate the catalyst are described...
February 2017: Nature Protocols
https://www.readbyqxmd.com/read/28124904/chitosan-film-containing-an-iron-complex-synthesis-and-prospects-for-heterocyclic-aromatic-amines-haas-recognition
#16
Maria Aparecida S da Silva, Dieric S Abreu, Leandro A Costa, Natanna de A Aguiar, Tércio F Paulo, Elisane Longhinotti, Izaura C N Diógenes
Hybrid organic-inorganic materials have been seen as a promising approach to produce sensors for the detection and/or recognition of heterocyclic aromatic amines (HAAs). This work shows the synthesis of a hybrid film as a result of the incorporation of [Fe(CN)5(NH3)](3-) into chitosan (CS); CS-[(CN)5Fe(NH3)](3-). The sensitivity of CS-[(CN)5Fe(NH3)](3-) toward HAA-like species was evaluated by using pyrazine (pz) as probe molecule in vapor phase by means of electrochemistry and spectroscopic techniques. The crystallinity (SEM-EDS and XRD) decrease of CS-[(CN)5Fe(NH3)](3-) in comparison to CS was assigned to the disturbance of the hydrogen bond network within the polymer...
February 7, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28120894/regioselectivity-and-mechanism-of-synthesizing-n-substituted-2-pyridones-and-2-substituted-pyridines-via-metal-free-c-o-and-c-n-bond-cleaving-of-oxazoline-3-2-a-pyridiniums
#17
Bo Li, Susu Xue, Yang Yang, Jia Feng, Peng Liu, Yong Zhang, Jianming Zhu, Zhijian Xu, Adrian Hall, Bo Zhao, Jiye Shi, Weiliang Zhu
Novel intermediate oxazoline[3,2-a]pyridiniums were facilely prepared from 2-(2,2-dimethoxyethoxy)-pyridines via acid promoted intramolecular cyclization. Sequentially, the quaternary ammonium salts were treated with different nucleophiles for performing regioselective metal-free C-O and C-N bond-cleaving to afford prevalent heterocyclic structures of N-substituted pyridones and 2-substituted pyridines. The reaction mechanism and regioselectivity were then systematically explored by quantum chemistry calculations at B3LYP/6-31 g(d) level...
January 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28120464/the-3-nitro-2-pyridinesulfenyl-group-synthesis-and-applications-to-peptide-chemistry
#18
Cédric Rentier, Kentarou Fukumoto, Akihiro Taguchi, Yoshio Hayashi
The 3-nitro-2-pyridinesulfenyl chloride, commonly abbreviated as Npys-Cl, was among the first stable heterocyclic sulfenyl halides to be isolated. After its discovery, the Npys group was widely used as a protecting group for the amines, alcohols and thiols. Herein, we have reviewed some of the aspects of the Npys-Cl moiety, and its most promising recent uses are summarized, from the stability of the Npys protection of amines, hydroxyls and thiols and removal conditions for potential applications in peptide synthesis, to one of its most successful applications for the formation of mixed disulfides...
January 25, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28112931/a-combined-experimental-and-molecular-simulation-study-of-factors-influencing-the-selection-of-antioxidants-in-butadiene-rubber
#19
Wei Zheng, Youping Wu, Wei Yang, Zhuo Zhang, Liqun Zhang, Sizhu Wu
For the selection of antioxidants, internal factors were proposed by analyzing the thermal-oxidative aging process, which consisted of the following two inseparable steps: (1) the physical process of oxygen (O2) entering the rubber network and (2) the complex chemical process of O2 reacting with the rubber network. Antioxidants 2246, 6PPD, and MB, examples of amines, phenols, and heterocycles, respectively, were chosen to study these factors influencing the selection of antioxidants for the thermal-oxidative aging of butadiene rubber (BR)...
February 7, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28111873/tandem-oxidative-c-h-amination-and-iodization-to-synthesize-difunctional-atropoisomeric-p-stereogenic-phosphinamides
#20
Shangdong Yang, Yan-Na Ma, Xi Zhang
An efficient metal-free tandem intramolecular oxidative C-H amination and iodization of phosphinamide has been performed and a series of novel phosphorus heterocyclic compounds was obtained. This method provides a concise and highly valuable pathway for the synthesis of difunctional atropoisomeric P-stereogenic phosphinamides.
January 23, 2017: Chemistry: a European Journal
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