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https://www.readbyqxmd.com/read/29774914/a-catalyst-controlled-switchable-reaction-of-%C3%AE-keto-acids-to-silyl-glyoxylates
#1
Man-Yi Han, Hong Pan, Jing Lin, Wei Li, Pinhua Li, Lei Wang
A catalyst-controlled switchable reaction of β-keto acids to silyl glyoxylates was developed under mild conditions, providing two distinct products in good yields. Compared to decarboxylative addition-Brook rearrangement, the decarboxylative addition products could be controlled by using a simple bifunctional organocatalyst thiourea derivative instead of DABCO. This new reaction model of silyl glyoxylates offered a facile and alternative route to organosilicon compounds.
May 18, 2018: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29771821/the-effects-of-exercise-aspirin-and-celecoxib-in-an-atherogenic-environment
#2
Heather Grimm, Jan Kretzschmar, Marc D Cook, Michael D Brown
INTRODUCTION: Optimal vascular function is a hallmark of cardiovascular health. Specifically, the balance of vasoconstricting and vasodilating substances is recognized as a marker of vascular health. One of the greatest challenges to vascular health and vasodilatory balance is tumor necrosis factor alpha (TNFα) mediated inflammation. Uncovering effective strategies that maintain a vascular environment that is more vasodilatory and anti-thrombotic in the face of an inflammatory challenge is favorable...
April 30, 2018: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/29771123/carotenoids-experimental-ionization-energies-and-capacity-at-inhibiting-lipid-peroxidation-in-a-chemical-model-of-dietary-oxidative-stress
#3
Olivier Dangles, Pascale Goupy, Michel Carail, Alexandre Giuliani, Denis Duflot, Catherine Caris-Veyrat
Carotenoids are important natural pigments and micronutrients contributing to health prevention by several mechanisms, including their electron-donating (antioxidant) activity. In this work, a large series of carotenoids, including 11 carotenes and 14 xanthophylls, has been investigated by wavelength-resolved atmospheric pressure photoionization mass spectrometry (DISCO line of SOLEIL synchrotron), thus allowing the experimental determination of their ionization energy (IE) for the first time. On the other hand, the carotenoids have been also investigated for their ability to inhibit the heme iron-induced peroxidation of linoleic acid in mildly acidic micelles, a simple but relevant chemical model of oxidative stress in the gastric compartment...
May 17, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29769077/magnetic-field-distribution-modulation-of-intrathecal-delivered-ketorolac-iron-oxide-nanoparticle-conjugates-produce-excellent-analgesia-for-chronic-inflammatory-pain
#4
Ping-Ching Wu, Dar-Bin Shieh, Hung-Tsung Hsiao, Jeffery Chi-Fei Wang, Ya-Chi Lin, Yen-Chin Liu
BACKGROUND: Nanoparticles have become one of the most promising among the potential materials used for biomedical applications. However, few researchers have focused on their effects on analgesia. Despite the fact that various nanoparticles have been evaluated for drug delivery and MRI imaging contrast enhancement in clinical settings, no reports have investigated the in vivo synergy of ketorolac iron-oxide nanoparticle conjugates to improve the analgesic effect. METHODS: Ketorolac conjugated magnetic iron oxide nanoparticles (Keto-SPIO) were synthesized via two-stage additions of protective agents and chemical co-precipitation...
May 16, 2018: Journal of Nanobiotechnology
https://www.readbyqxmd.com/read/29768657/simultaneous-quantification-of-fentanyl-sufentanil-cefazolin-doxapram-and-keto-doxapram-in-plasma-using-liquid-chromatography-tandem-mass-spectrometry
#5
Robert B Flint, Soma Bahmany, Bart C H van der Nagel, Birgit C P Koch
A simple and specific UPLC-MS/MS method was developed and validated for simultaneous quantification of fentanyl, sufentanil, cefazolin, doxapram and its active metabolite keto-doxapram. The internal standard was fentanyl-d5 for all analytes. Chromatographic separation was achieved with a reversed phase Acquity UPLC HSS T3 column with a run-time of only 5.0 minutes per injected sample. Gradient elution was performed with a mobile phase consisting of ammonium acetate, formic acid in Milli-Q ultrapure water or in methanol with a total flow rate of 0...
May 16, 2018: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/29767977/predicting-the-keto-enol-equilibrium-from-combining-uv-visible-absorption-spectroscopy-with-quantum-chemical-calculations-of-vibronic-structures-for-many-excited-states-a-case-study-on-salicylideneanilines
#6
Freddy Zutterman, Orian Louant, Gabriel M Mercier, Tom Leyssens, Benoît Champagne
Salicylideneanilines are characterized by a tautomer equilibrium, between an enol and a keto form of different colors, at the origin of their remarkable thermochromic, solvatochromic, and photochromic properties. The enol form is usually the most stable but appropriate choice of substituents and conditions (solvent, crystal, host compound) can displace the equilibrium towards the keto form so that there is a need for fast prediction of the keto:enol abundance ratio. Here we demonstrate the reliability of a combined theoretical-experimental method, based on comparing simulated and measured UV/visible absorption spectra...
May 16, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29767961/real-time-monitoring-of-tricarboxylic-acid-metabolites-in-exhaled-breath
#7
Alberto Tejero Rioseras, Kapil Dev Singh, Nora Nowak, Martin T Gaugg, Tobias Bruderer, Renato Zenobi, Pablo M-L Sinues
The tricarboxylic acid (TCA) cycle is one of the most important metabolic pathway for cellular respiration in aerobic organisms. It provides and collects intermediates for many other interconnecting pathways and acts as a hub connecting metabolism of carbohydrates, fatty acids, and amino acids. Alteration in intracellular levels of its intermediates has been linked with a wide range of illnesses ranging from cancer to cellular necrosis or liver cirrhosis. Therefore, there exists an intrinsic interest in monitoring such metabolites...
May 16, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29767187/separately-enhanced-dual-emissions-of-the-amphiphilic-derivative-of-2-2-hydroxylphenyl-benzothiazole-by-supramolecular-complexation
#8
Chengfeng Wu, Yingzhi Jin, Dahua Li, Lan Ding, Yuzhi Xing, Kaicheng Zhang, Bo Song
Here, we report separately enhanced dual emissions of the amphiphilic derivative of 2-(2'-hydroxyphenyl)benzothiazole (denoted as HBT-11) by supramolecular complexation with cyclodextrins (CDs). When dispersed in water, HBT-11 shows two relatively weak emission bands, which can be assigned to the emissions of enol- and keto-forms, the two tautomers, owing to excited-state intramolecular proton transfers. Upon the addition of α-CD and β-CD, the keto- and enol-emissions, respectively, are separately enhanced; the enhancement effect is due to the formation of HBT-11/α-CD and HBT-11/β-CD complexes through multiple hydrogen bonding and host-guest interactions, respectively...
May 16, 2018: Soft Matter
https://www.readbyqxmd.com/read/29765715/crystal-structure-and-hirshfeld-surface-analysis-of-e-4-2-4-hy-droxy-benzo-yl-hydrazin-1-yl-idene-meth-yl-pyridin-1-ium-nitrate
#9
Mir Abolfazl Naziri, Ertan Şahin, Tuncer Hökelek
The asymmetric unit of the title aroyl hydrazone Schiff base salt, C13 H12 N3 O2 + ·N O3 - , consists of one mol-ecular cation in the keto tautomeric form, adopting an E configuration with respect to the azomethine bond, and one nitrate anion. The two units are linked via an N-H⋯O hydrogen bond. The mol-ecule overall is non-planar, with the pyridinium and benzene rings being inclined to each other by 4.21 (4)°. In the crystal, cations and anions are linked via inter-molecular O-H⋯O and bifurcated N-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (101)...
March 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/29765714/synthesis-crystal-structure-and-computational-studies-of-a-new-schiff-base-compound-e-4-bromo-2-eth-oxy-6-2-meth-oxy-phen-yl-imino-meth-yl-phenol
#10
Arzu Özek Yıldırım, Murat Gülsu, Çiğdem Albayrak Kaştaş
The title compound, C16 H16 BrNO3 , which shows enol-imine tautomerism, crystallizes in the monoclinic P 21 / c space group. All non-H atoms of the mol-ecule are nearly coplanar, with a maximum deviation of 0.274 (3) Å. In the crystal, mol-ecules are held together by weak C-H⋯O, π-π and C-H⋯π inter-actions. The E / Z isomerism and enol/keto tautomerism energy barriers of the compound have been calculated by relaxed potential energy surface scan calculations with DFT methods. To observe the changes in the aromatic ring, HOMA aromaticity indexes were calculated during the scan process...
March 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/29764289/divergent-induction-of-branched-chain-aminotransferases-and-phosphorylation-of-branched-chain-keto-acid-dehydrogenase-is-a-potential-mechanism-coupling-bcka-mediated-astrocyte-activation-to-bcaa-depletion-mediated-cognitive-deficit-after-tbi
#11
Guoqiang Xing, Ming Ren, Ajay Verma
Deficient branched chain amino acids (BCAAs) are implicated in cognitive dysfunction after traumatic brain injury (TBI). The mechanism remains unknown. BCAAs are catabolized by neuron-specific cytosolic and astrocyte-specific mitochondrial branched chain aminotransferases (BCATc, BCATm) to generate glutamate and branched-chain keto-acids (BCKAs) that are metabolized via the mitochondrial branched-chain-keto-acid dehydrogenase (BCKD) whose activity is regulated by its phosphorylation state. BCKD phosphorylation by BCKD kinase (BCKDK) inactivates BCKD and cause neuro-cognitive dysfunction, whereas de-phosphorylation by specific phosphatase restores BCKD activity...
May 15, 2018: Journal of Neurotrauma
https://www.readbyqxmd.com/read/29763686/mice-deficient-in-aldo-keto-reductase-1a-akr1a-are-resistant-to-thioacetamide-induced-liver-injury
#12
Takujiro Homma, Takaya Shirato, Ryusuke Akihara, Sho Kobayashi, Jaeyong Lee, Ken-Ichi Yamada, Satoshi Miyata, Motoko Takahashi, Junichi Fujii
Aldehyde reductase (Akr1a) has been reported to be involved in detoxification of reactive aldehydes as well as in the synthesis of bioactive compounds such as ascorbic acid (AsA). Because Akr1a is expressed at high levels in the liver and is involved in xenobiotic metabolism, our objective was to investigate the hepato-protective role of Akr1a in a thioacetamide (TAA)-induced hepatotoxicity model using Akr1a-deficient (Akr1a-/- ) mice. Wild-type (WT) and Akr1a-/- mice were injected intraperitoneally with TAA and the extent of liver injury in the acute phase was assessed...
May 12, 2018: Toxicology Letters
https://www.readbyqxmd.com/read/29757201/antioxidant-structure%C3%A2-activity-relationship-analysis-of-five-dihydrochalcones
#13
Xican Li, Ban Chen, Hong Xie, Yuhua He, Dewei Zhong, Dongfeng Chen
The study determined the comparative antioxidant capacities of five similar dihydrochalcones: phloretin, phloridzin, trilobatin, neohesperidin dihydrochalcone, and naringin dihydrochalcone. In the ferric-reducing antioxidant power (FRAP) assay, the antioxidant activities of pairs of dihydrochalcones had the following relationship: phloretin > phloridzin, phloretin > trilobatin, trilobatin > phloridzin, trilobatin > naringin dihydrochalcone, and neohesperidin dihydrochalcone > naringin dihydrochalcone...
May 12, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29755574/branched-chain-amino-acids-in-health-and-disease-metabolism-alterations-in-blood-plasma-and-as-supplements
#14
REVIEW
Milan Holeček
Branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) are essential amino acids with protein anabolic properties, which have been studied in a number of muscle wasting disorders for more than 50 years. However, until today, there is no consensus regarding their therapeutic effectiveness. In the article is demonstrated that the crucial roles in BCAA metabolism play: (i) skeletal muscle as the initial site of BCAA catabolism accompanied with the release of alanine and glutamine to the blood; (ii) activity of branched-chain keto acid dehydrogenase (BCKD); and (iii) amination of branched-chain keto acids (BCKAs) to BCAAs...
2018: Nutrition & Metabolism
https://www.readbyqxmd.com/read/29751080/prenylated-%C3%AE-diketones-two-new-additions-to-the-family-of-biologically-active-hypericum-perforatum-l-hypericaceae-secondary-metabolites
#15
Niko S Radulović, Marija S Genčić, Nikola M Stojanović, Pavle J Randjelović, Nicolas Baldovini, Vanya Kurteva
Two novel β-diketones, 2,6,9-trimethyl-8-decene-3,5-dione (A) and 3,7,10-trimethyl-9-undecene-4,6-dione (B), were identified from the renowned medicinal plant Hypericum perforatum L. The structures of β-diketones A and B were corroborated by syntheses (4 steps starting from methyl acetoacetate, overall yields 30% and 23%, respectively). In solution, these β-diketones predominantly exist as two rapidly interconverting β-keto-enol tautomers. The structures of A and B show some common fragments with the molecules of hyperforin and adhyperforin, respectively, the acknowledged multi-target secondary metabolites from St...
May 8, 2018: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/29750577/gemcitabine-analogues-with-4-n-alkyl-chain-modified-with-fluoromethyl-ketone-group
#16
Cesar Gonzalez, Maria de Cabrera, Stanislaw F Wnuk
Gemcitabine analogues with a lipophilic 4-N-alkyl chain bearing a terminal β-keto sulfonate moiety suitable for fluorination compatible with 18 F-radiolabeling have been explored. Displacement of p-toluenesulfonylamino in protected 4-N-tosylgemcitabine with 1-amino-10-undecene gave 4-N-(10-undecenyl)-3',5'-di-O-benzoyl-2'-deoxy-2',2'-difluorocytidine. Oxidation of the terminal double bond in the latter with OsO4 /NMO afforded 4-N-(10,11-dihydroxyundecanyl) derivative. Regioselective sulfonation of primary hydroxyl followed by oxidation of secondary hydroxyl with Collin's reagent yielded desired β-keto sulfonate analogues 8 or 9...
May 11, 2018: Nucleosides, Nucleotides & Nucleic Acids
https://www.readbyqxmd.com/read/29749651/effects-of-immunosuppressive-agents-on-the-hemostatic-system-in-normal-dogs
#17
John M Thomason, Todd M Archer, Robert W Wills, Andrew J Mackin
BACKGROUND: In dogs, the effects of immunosuppressive medications on hemostasis are not well known. HYPOTHESIS/OBJECTIVES: The objective was to determine the effects of immunosuppressive medications on primary and secondary hemostasis. Our hypothesis was that cyclosporine and prednisone would increase markers of hypercoagulability and thromboxane synthesis, while azathioprine, mycophenolate mofetil, and leflunomide would have minimal effects on hemostasis. ANIMALS: Eight healthy dogs...
May 10, 2018: Journal of Veterinary Internal Medicine
https://www.readbyqxmd.com/read/29744366/astaxanthin-promotes-nrf2-are-signaling-to-alleviate-renal-fibronectin-and-collagen-iv-accumulation-in-diabetic-rats
#18
Xiaoyu Zhu, Yongjun Chen, Qing Chen, Huiyuan Yang, Xi Xie
Astaxanthin (AST), a natural keto-carotenoid classified as a xanthophyll, is well known for its antioxidant properties. AST can ameliorate the pathological characteristics of diabetic nephropathy (DN). However, the underlying mechanisms remain to be explored. This study was aimed at exploring whether AST exerts a protective effect on DN via activating nuclear factor erythroid 2-related factor 2- (Nrf2-) antioxidative response element (ARE) signaling. Streptozotocin-induced diabetic rats were treated with AST for 12 weeks...
2018: Journal of Diabetes Research
https://www.readbyqxmd.com/read/29743477/biosynthetic-pathway-for-furanosteroid-demethoxyviridin-and-identification-of-an-unusual-pregnane-side-chain-cleavage
#19
Gao-Qian Wang, Guo-Dong Chen, Sheng-Ying Qin, Dan Hu, Takayoshi Awakawa, Shao-Yang Li, Jian-Ming Lv, Chuan-Xi Wang, Xin-Sheng Yao, Ikuro Abe, Hao Gao
Furanosteroids, represented by wortmannin, viridin, and demethoxyviridin, are a special group of fungal-derived, highly oxygenated steroids featured by an extra furan ring. They are well-known nanomolar-potency inhibitors of phosphatidylinositol 3-kinase and widely used in biological studies. Despite their importance, the biosyntheses of these molecules are poorly understood. Here, we report the identification of the biosynthetic gene cluster for demethoxyviridin, consisting of 19 genes, and among them 15 biosynthetic genes, including six cytochrome P450 monooxygenase genes, are deleted...
May 9, 2018: Nature Communications
https://www.readbyqxmd.com/read/29741101/ent-abietane-diterpenoids-from-suregada-zanzibariensis-baill-euphorbiaceae-their-cytotoxic-and-anticancer-properties
#20
Mandisa Mangisa, Vuyelwa J Tembu, Gerda Fouche, Rudzani Nthambeleni, Xolani Peter, Moses K Langat
The stem bark extract of Suregada zanzibariensis afforded a previously undescribed ent-abietane diterpenoid trivially named mangiolide (1) and a known jolkinolide B (2) via anticancer bioassay-guided fractionation. The CH2 Cl2 :MeOH extract of S. zanzibariensis was initially analysed for its anticancer properties against three cancer cell lines, renal (TK10), melanoma (UACC62), and breast (MCF7) and was found to be potent at low μg/mL ranges. Compound 1, 6α-acetoxy-14-keto-ent-abieta-7(8),13(15)-diene-16,12-olide (mangiolide) inhibited the growth of renal (TK10) with a GI50 of 0...
May 9, 2018: Natural Product Research
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