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https://www.readbyqxmd.com/read/30526445/dicarboxylic-acids-and-related-compounds-in-pm-2-5-aerosols-in-huangshi-central-china
#1
Hongxia Liu, Kimitaka Kawamura, Bhagawati Kunwar, Junji Cao, Jiaquan Zhang, Changlin Zhan, Jingru Zheng, Ruizhen Yao, Ting Liu, Wensheng Xiao
PM2.5 samples were collected in Huangshi (HS), central China from March 2012 to February 2013 and were analyzed for dicarboxylic acids (diacids) and related compounds (DARCs). Oxalic acid (C2 , 416 ng m-3 ) was the most abundant species, followed by phthalic (Ph, 122 ng m-3 ), terephthalic (tPh, 116 ng m-3 ), succinic (C4 , 70.4 ng m-3 ), azelaic (C9 , 67.9 ng m-3 ) and adipic (C6 , 57.8 ng m-3 ) acids . Relatively high abundances of Ph and tPh differed from the distribution in urban and marine aerosols, indicating contributions from nearby anthropogenic sources...
December 10, 2018: Journal of the Air & Waste Management Association
https://www.readbyqxmd.com/read/30525582/effect-of-roasting-and-storage-on-the-formation-of-maillard-reaction-and-sugar-degradation-products-in-hazelnuts-corylus-avellana-l
#2
Neslihan Göncüoğlu Taş, Vural Gökmen
This study investigated the effect of roasting (150C for 30 min) and storage (12 months at 4C, 25C and 25C in vacuum package), conditions of which are generally applied in the industry and markets, on the formation of Maillard reaction and sugar degradation products, namely dicarbonyl compounds, 5-hydroxymethylfurfural, N--fructosyllysine, and N--carboxymethyllysine in Tombul and Levant hazelnuts. Roasting increased all dicarbonyl compounds significantly (p<0.05). The concentration of methylglyoxal was highest while 1-deoxyglucosone was lowest in roasted hazelnuts...
December 10, 2018: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/30508605/age-related-alteration-in-the-distribution-of-methylglyoxal-and-its-metabolic-enzymes-in-the-mouse-brain
#3
Shin Koike, Chihiro Ando, Yosuke Usui, Yosuke Kibune, Shoichi Nishimoto, Toshihiro Suzuki, Yuki Ogasawara
Methylglyoxal (MG) is an α-dicarbonyl compound that is naturally produced in vivo through glucose metabolism. In general, MG is metabolized by the glyoxalase 1(GLO1)/GLO2 system and aldose reductase (AR); however, excessive MG can react with proteins and nucleic acids to induce the accumulation of advanced glycation end products (AGEs). Recently, the accumulation of AGEs in the brain has been presumed to be related to neurodegenerative diseases such as Parkinson's and Alzheimer's disease, respectively. Research investigating the role of AGEs in such diseases is ongoing...
November 30, 2018: Brain Research Bulletin
https://www.readbyqxmd.com/read/30499298/formation-and-optical-properties-of-brown-carbon-from-small-%C3%AE-dicarbonyls-and-amines
#4
Wilmarie Marrero-Ortiz, Min Hu, Zhuofei Du, Yuemeng Ji, Yujue Wang, Song Guo, Yun Lin, Mario Gomez-Hermandez, Jianfei Peng, Yixin Li, Jeremiah Secrest, Misti Levy Zamora, Yuan Wang, Taicheng An, Renyi Zhang
Brown Carbon (BrC) aerosols scatter and absorb solar radiation, directly affecting the Earth's radiative budget. However, considerable uncertainty exists concerning the chemical mechanism leading to BrC formation and their optical properties. In this work, BrC particles were prepared from mixtures of small α-dicarbonyls (glyoxal and methylglyoxal) and amines (methylamine, dimethylamine, and trimethylamine). The absorption and scattering of BrC particles were measured using a photo-acoustic extinctometer (405 and 532 nm), and the chemical composition of the α-dicarbonyl-amine mixtures was analyzed using orbitrap-mass spectrometry and thermal desorption-ion drift-chemical ionization mass spectrometry...
November 30, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/30482147/exogenous-3-deoxyglucosone-induced-carbonyl-and-oxidative-stress-causes-%C3%AE-cells-dysfunction-by-impairing-gut-permeability-in-rats
#5
L Zhou, X D Song, H Xu, G Q Liang, F Wang, L R Zhang, F Huang, J Cai, G R Jiang
3-Deoxyglucosone (3DG) is a highly reactive dicarbonyl species, and its accumulation evokes carbonyl and oxidative stress. Our recent data reveal the role of 3DG as an independent factor for the development of prediabetes and suggest that intestine could be its novel target tissue. The present study investigated whether exogenous 3DG increases intestinal permeability by triggering carbonyl and oxidative stress, thus contributing to β-cell dysfunction. Rats were administered 3DG for two weeks by gastric gavage...
November 2018: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/30463337/a-simple-and-efficient-synthesis-of-highly-substituted-indeno-1-2-b-pyrrole-and-acenaphtho-1-2-b-pyrrole-derivatives-by-tandem-three-component-reactions
#6
Xiaodong Tang, Songlei Zhu, Ying Ma, Ren Wen, Lanqi Cen, Panwei Gong, Jing Wang
A green, convenient and tandem procedure for the efficient synthesis of highly substituted indeno[1,2- b ]pyrrole and acenaphtho[1,2- b ]pyrrole derivatives by domino three-component reaction of tryptamine/benzylamine, 1,3-dicarbonyl compounds and ninhydrin/ acenaphthenequinone is described. The significant features of this procedure were characterized by mild reaction conditions, high yields, operational simplicity and it being environmentally benign.
November 20, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/30444310/catalytic-enantioselective-%C3%AE-ketol-rearrangement
#7
Hua Wu, Rémi Andres, Qian Wang, Jieping Zhu
A highly enantioselective α-ketol rearrangement has been developed. In the presence of chiral Cu-bisoxazoline complex, the achiral β-hydroxy-α-dicarbonyls were isomerized to chiral α-hydroxy-β-dicarbonyls and their bicyclic derivatives in excellent yields and enantioselectivities. Enantioenriched 2-acyl-2-hydroxy cyclohexan-1-ones, dihydroxyhexahydrobenzofuranones and dihydroxyhexahydro-cycloheptafuranones with up to three stereocenters were readily prepared from achiral starting materials in one operation...
November 16, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30423209/the-role-of-mass-spectrometry-in-studies-of-glycation-processes-and-diabetes-management
#8
REVIEW
Sara D'Aronco, Sara Crotti, Marco Agostini, Pietro Traldi, Nino Cristiano Chilelli, Annunziata Lapolla
In the last decade, mass spectrometry has been widely employed in the study of diabetes. This was mainly due to the development of new, highly sensitive, and specific methods representing powerful tools to go deep into the biochemical and pathogenetic processes typical of the disease. The aim of this review is to give a panorama of the scientifically valid results obtained in this contest. The recent studies on glycation processes, in particular those devoted to the mechanism of production and to the reactivity of advanced glycation end products (AGEs, AGE peptides, glyoxal, methylglyoxal, dicarbonyl compounds) allowed to obtain a different view on short and long term complications of diabetes...
November 13, 2018: Mass Spectrometry Reviews
https://www.readbyqxmd.com/read/30419156/stereocontrolled-synthesis-of-1-4-dicarbonyl-compounds-by-photochemical-organocatalytic-acyl-radical-addition-to-enals
#9
Giulio Goti, Bartosz Bieszczad, Alberto Vega-Peñaloza, Paolo Melchiorre
We report a visible-light-mediated organocatalytic strategy for the enantioselective acyl radical conjugate addition to enals, leading to valuable 1,4-dicarbonyl compounds. The process capitalizes upon the excited-state reactivity of 4-acyl-1,4-dihydropyridines that, upon visible-light absorption, can trigger the generation of acyl radicals. By means of a chiral amine catalyst, iminium ion activation of enals ensures a stereoselective radical trap. We also demonstrate how the combination of this acylation process with a second catalyst-controlled bond-forming event allows to selectively access the full matrix of all possible stereoisomers of the resulting 2,3-substituted 1,4-dicarbonyl products...
November 12, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30415846/lactobacillus-casei-expressing-methylglyoxal-synthase-causes-browning-and-heterocyclic-amine-formation-in-parmesan-cheese-extract
#10
N N Gandhi, G Barrett-Wilt, J L Steele, S A Rankin
Undesired browning of Parmesan cheese can occur during the latter period of ripening and cold storage despite the relative absence of reducing sugars and high temperatures typically associated with Maillard browning. Highly reactive α-dicarbonyls such as methylglyoxal (MG) are products and accelerants of Maillard browning chemistry and can result from the microbial metabolism of sugars and AA by lactic acid bacteria. We demonstrate the effects of microbially produced MG in a model Parmesan cheese extract using a strain of Lactobacillus casei 12A engineered for inducible overexpression of MG synthase (mgsA) from Thermoanaerobacterium thermosaccharolyticum HG-8...
November 8, 2018: Journal of Dairy Science
https://www.readbyqxmd.com/read/30411034/reflex-carbocation-release-from-covalent-molecules-by-endogenous-free-radicals
#11
John C Walton
Carbocations are pervasive in contemporary organic synthesis, so new and innocuous methods of making them are always desirable. A theoretical approach revealed that compounds in which radical generation takes place may release carbocations advantageously. The radical types and molecular substructures that promote this effect were identified. The best substructures were found to be 1,3-dicarbonyl compounds, particularly those based on the Meldrum's acid theme. Sulfate esters and dithiane rings could also be employed...
October 31, 2018: ACS Omega
https://www.readbyqxmd.com/read/30410851/synthesis-of-metallomacrocycle-and-coordination-polymers-with-pyridine-based-amidocarboxylate-ligands-and-their-catalytic-activities-towards-the-henry-and-knoevenagel-reactions
#12
Anirban Karmakar, Guilherme M D M Rúbio, M Fátima C Guedes da Silva, Armando J L Pombeiro
The reactions of 3,3'-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2 L) with zinc(II), cadmium(II), and samarium(III) nitrates were studied, and the obtained compounds, [Zn(1κ O :2κ O' -L)(H2 O)2 ] n ( 1 ), [Cd(1κ O 2 :2κ O 2 -L)(H2 O)2 ]2 ⋅ 6 n  H2 O ⋅ n  C4 H8 O2 ⋅ 1.5 n  DMF ( 2 ), and [Sm(1κ O :2κO ' O '' :3κ O''' -L)(NO3 )(H2 O)(dmf)] n ⋅ n  DMF ( 3 ), were characterized by elemental analysis, FTIR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction...
November 2018: ChemistryOpen
https://www.readbyqxmd.com/read/30410620/microwave-assisted-synthesis-of-biologically-relevant-steroidal-17-exo-pyrazol-5-ones-from-a-norpregnene-precursor-by-a-side-chain-elongation-heterocyclization-sequence
#13
Gergő Mótyán, László Mérai, Márton Attila Kiss, Zsuzsanna Schelz, Izabella Sinka, István Zupkó, Éva Frank
Multistep syntheses of novel 17β-pyrazol-5'-ones in the Δ5 -androstane series were efficiently carried out from pregnenolone acetate. A steroidal 17-carboxylic acid was first synthesized as a norpregnene precursor by the bromoform reaction and subsequent acetylation. Its CDI-activated acylimidazole derivative was then converted to a β-ketoester containing a two carbon atom-elongated side chain than that of the starting material. A Knorr cyclization of the bifunctional 1,3-dicarbonyl compound with hydrazine and its monosubstituted derivatives in AcOH under microwave heating conditions led to the regioselective formation of 17- exo -heterocycles in good to excellent yields...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30408761/comparison-of-secondary-organic-aerosol-soa-formation-during-o-m-and-p-xylene-photooxidation
#14
Peng Zhang, Jingyun Huang, Jinian Shu, Bo Yang
Despite extensive effort to characterize xylene-isomer-derived secondary organic aerosols (SOAs) over the past decade, differences in SOA composition among xylene isomers, and their relative contributions to SOA formation remain poorly understood. Herein, we reinvestigated the photooxidation of o-, m-, and p-xylene under two limiting NO conditions. Dicarbonyls, TBM (the acronym of C3 -trione, 2,3-butanedione, and 3-methyl-2-oxiranecarbaldehyde with the same [M+H]+ m/z value of 87), and highly oxidized species (HOS), based on the m/z 61 fragment, were determined to be the predominant SOA components arising from xylene photooxidation; however, their relative contributions to SOA formation appear to depend on the xylene substitution pattern...
October 30, 2018: Environmental Pollution
https://www.readbyqxmd.com/read/30402995/enantioselective-electrophilic-aromatic-nitration-a-chiral-auxiliary-approach
#15
Joseph P Campbell, Sinu C Rajappan, Tyler J Jaynes, Mona Sharafi, Yong-Tao Ma, Jianing Li, Severin Thomas Schneebeli
Enantioselective electrophilic aromatic nitration methodology is needed to advance chirality-assisted synthesis (CAS). We now report an enantioselective aromatic nitration strategy operating with chiral diester auxiliaries, which provides an enantioselective synthesis of a C3v-symmetric tribenzotriquinacene (TBTQ). These axially-chiral structures are much sough-after building blocks for CAS, but they were not accessible prior to this work in enantioenriched form without resolution of enantiomers. Our nitration strategy controls the stereochemistry of threefold nitration reactions from above the aromatic rings with chiral diester arms...
November 6, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30398646/quercetin-but-not-epicatechin-decreases-plasma-concentrations-of-methylglyoxal-in-adults-in-a-randomized-double-blind-placebo-controlled-crossover-trial-with-pure-flavonoids
#16
Mathias D G Van den Eynde, Johanna M Geleijnse, Jean L J M Scheijen, Nordin M J Hanssen, James I Dower, Lydia A Afman, Coen D A Stehouwer, Peter C H Hollman, Casper G Schalkwijk
Background: Methylglyoxal (MGO) is the most potent precursor of advanced glycation end products (AGEs). MGO and AGEs have been associated with diabetes, its complications, and other age-related diseases. Experimental studies have shown that the flavonoids quercetin and epicatechin are able to scavenge MGO and lower AGE formation. Objective: Data on the effects of these flavonoids on MGO and AGE concentrations in humans are not yet available. We therefore investigated the effect of quercetin and epicatechin on the concentrations of MGO and AGEs in a post hoc analysis...
November 6, 2018: Journal of Nutrition
https://www.readbyqxmd.com/read/30391748/dysfunction-in-nitric-oxide-synthesis-in-streptozotocin-treated-rat-aorta-and-role-of-methylglyoxal
#17
Yousif A Shamsaldeen, Mahdi H Alsugoor, Lisa A Lione, Christopher D Benham
Diabetic vascular dysfunction is a major complication of diabetes. Methylglyoxal (MGO) is a dicarbonyl metabolite elevated in diabetic plasma that reacts with interstitial molecules to form advanced glycation end products (AGE). We investigated whether MGO affects the release of nitric oxide (NO) from rat aortic smooth muscle cells (ASMCs), and if L-arginine can prevent these effects of MGO. MGO was significantly elevated in serum from streptozotocin (STZ)-treated rats (121 ± 11.2 µM) compared with vehicle control rats (27...
November 2, 2018: European Journal of Pharmacology
https://www.readbyqxmd.com/read/30387392/drug-design-of-inhibitors-of-alzheimer-s-disease-ad-pom-and-dft-analyses-of-cholinesterase-inhibitory-activity-of-%C3%AE-amino-di-carbonyl-derivatives
#18
Taibi Ben Hadda, Abdur Rauf, Hsaine Zgou, Fatma Sezer Senol, Ilkay Erdogan Orhan, Yahia Nasser Mabkhot, Ismail I Althagafi, Thoraya A Farghaly
BACKGROUND: Since deficit of acetylcholine has been evidenced in the patients of Alzheimer's disease (AD), cholinesterase inhibitors are currently the most prescribed drug class for the treatment of AD. RESULTS: In the present study, 16 compounds (1-16) with dicarbonyl skeletons have been synthesized and tested for their inhibitory potential in vitro against AChE and BChE using ELISA microtiter plate assays at 100 µg/mL. Since metal accumulation is related to AD, the compounds were also tested for their metal-chelation capacity...
November 1, 2018: Mini Reviews in Medicinal Chemistry
https://www.readbyqxmd.com/read/30383065/an-efficient-method-for-retro-claisen-type-c-c-bond-cleavage-of-diketones-with-tropylium-catalyst
#19
M A Hussein, V T Huynh, R Hommelsheim, R M Koenigs, T V Nguyen
The retro-Claisen reaction is frequently used in organic synthesis to access ester derivatives from 1,3-dicarbonyl precursors. The C-C bond cleavage in this reaction is usually promoted by a number of transition-metal Lewis acid catalysts or organic Brønsted acids/bases. Herein we report a new convenient and efficient method utilizing the tropylium ion as a mild and environmentally friendly organocatalyst to mediate retro-Claisen-type reactions. Using this method, a range of synthetically valuable substances can be accessed via solvolysis of 1,3-dicarbonyl compounds...
November 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/30375153/copper-catalyzed-c-h-activation
#20
REVIEW
M Lakshmi Kantam, Chandrakanth Gadipelly, Gunjan Deshmukh, K Rajender Reddy, Suresh Bhargava
Activation of C-H bonds and their application in cross coupling chemistry has received a wider interest in recent years. The conventional strategy in cross coupling reaction involves the pre-functionalization step of coupling reactants such as organic halides, pseudo-halides and organometallic reagents. The C-H activation facilitates a simple and straight forward approach devoid of pre-functionalization step. This approach also addresses the environmental and economical issues involved in several chemical reactions...
October 30, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
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