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Venkatesan Kathiresan, Swathika Subburaman, Arun Venkatesh Krishna, Mathivanan Natarajan, Gandhidasan Rathinasamy, Kumaresan Ganesan, Murugesan Ramachandran
Doxorubicin (DOX) is a well-known cytotoxic agent used extensively as a chemotherapeutic drug to eradicate a wide variety of human cancers. Reactive oxygen species (ROS)-mediated oxidative stress during DOX treatment can induce cardiac, renal, and hepatic toxicities, which can constrain its use as a potential cytotoxic agent. The present work investigates the antioxidant potential of naringenin (NAR) against DOXinduced toxicities of a Dalton's lymphoma ascites (DLA) tumor-bearing mouse model. Mice were randomized into four groups: a negative control, positive control, DOX (2...
2016: Journal of Environmental Pathology, Toxicology and Oncology
Longmei Zhai, Dashuang Xiao, Chaohua Sun, Ting Wu, Zhenhai Han, Xinzhong Zhang, Xuefeng Xu, Yi Wang
To cope with iron (Fe) deficiency, plants have evolved a wide range of adaptive responses from changes in morphology to altered physiological responses. Recent studies have demonstrated that nitric oxide (NO) is involved in the Fe-deficiency response through hormonal signaling pathways. Here, we report that NO plays a significant role in Malus xiaojinensis, an Fe-efficient woody plant. Fe deficiency triggered significant accumulation of NO in the root system, predominantly in the outer cortical and epidermal cells of the elongation zone...
November 6, 2016: Plant Physiology and Biochemistry: PPB
Amram Samuni, Eric Maimon, Sara Goldstein
Stable nitroxide radicals have multiple biological effects, although the mechanisms underlying them are not fully understood. Their protective effect against oxidative damage has been mainly attributed to scavenging deleterious radicals, oxidizing reduced metal ions and reducing oxyferryl centers of heme proteins. Yet, the potential of nitroxides to protect heme proteins against inactivation while suppressing or enhancing their catalytic activities has been largely overlooked. We have studied the effect of nitroxides, including TPO (2,2,6,6-tetramethylpiperidin-N-oxyl), 4-OH-TPO, 4-oxo-TPO and 3-carbamoyl proxyl, on the peroxidase-like activity of metmyoglobin (MbFe(III)) and methemoglobin (HbFe(III)) using nitrite as an electron donor by following heme absorption, H2O2 consumption, O2 evolution and nitrite oxidation...
November 5, 2016: Free Radical Biology & Medicine
Bianca Hemmeryckx, Philipp Hohensinner, Melissa Swinnen, Ward Heggermont, Johann Wojta, Henri Roger Lijnen
Bmal1-(brain and muscle ARNT-like protein-1) deficient (Bmal1) mice prematurely age because of an increased reactive oxygen species (ROS) production. These mice also show a decline in cardiac function with age. We investigated whether an antioxidant treatment can ameliorate the declining cardiac function in prematurely aged Bmal1 mice. Male Bmal1 and wild-type (Bmal1) mice were exposed for 15 weeks to a high fat and high cholesterol diet with or without the antioxidant 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL; 5 mmol/L; in drinking water during the last 10 weeks)...
November 2016: Journal of Cardiovascular Pharmacology
Elena G Kovaleva, Leonid S Molochnikov, Darya P Stepanova, Alexander V Pestov, Dmitrii G Trofimov, Igor A Kirilyuk, Alex I Smirnov
Acid-base equilibria and interfacial electrostatic properties of hydrated mesoporous and nanostructured alumina powders are determining factors for the use of these materials in heterogeneous catalysis and as a sorption media for filtration and chromatographic applications including life sciences. Here spin probe electron paramagnetic resonance spectroscopy of pH-sensitive nitroxides was employed to evaluate the surface charge and interfacial acid-base equilibria at the pore surface of mesoporous powders of α-Al2O3, γ-Al2O3, Al2O3 × nH2O, and basic γ-Al2O3 and nanostructured Al2O3 in the form of pristine materials and modified with aluminum-tri-sec-butoxide, hydroxyaluminum glycerate, and several phospholipids...
November 4, 2016: Cell Biochemistry and Biophysics
Domenick F Leto, Allyssa A Massie, Derek B Rice, Timothy A Jackson
The mononuclear Mn(IV)-oxo complex [MnIV(O)(N4py)]2+, where N4py is the pentadentate ligand N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine, has been proposed to attack C-H bonds by an excited-state reactivity pattern [Cho, K.-B.; Shaik, S.; Nam, W., J. Phys. Chem. Lett. 2012, 3, 2851-2856]. In this model, a 4E excited state is utilized to provide a lower-energy barrier for hydrogen-atom transfer. This proposal is intriguing, as it offers both a rationale for the relatively high hydrogen-atom transfer reactivity of [MnIV(O)(N4py)]2+ and a guideline for creating more reactive complexes through ligand modification...
November 1, 2016: Journal of the American Chemical Society
Yuji Nadatani, Xiaofang Huo, Xi Zhang, Chunhua Yu, Edaire Cheng, Qiuyang Zhang, Kerry B Dunbar, Arianne Theiss, Thai H Pham, David H Wang, Toshio Watanabe, Yasuhiro Fujiwara, Tetsuo Arakawa, Stuart J Spechler, Rhonda F Souza
BACKGROUND & AIMS: Microbial molecular products incite intestinal inflammation by activating Toll-like receptors (TLRs) and inflammasomes of the innate immune system. This system's contribution to esophageal inflammation is not known. Gram-negative bacteria, which dominate the esophageal microbiome in reflux esophagitis, produce lipopolysaccharide (LPS), a TLR4 ligand. TLR4 signaling produces pro-interleukin (IL)1β, pro-IL18, and NOD-like receptor protein 3 (NLRP3), which prime the NLRP3 inflammasome...
July 2016: Cellular and Molecular Gastroenterology and Hepatology
Ping Yin, Lauren A Mitchell, Damon A Parrish, Jean'ne M Shreeve
N-Nitramino/N-oxyl functionalization strategies were employed to investigate structure-property relationships of energetic materials. Based on single-crystal diffraction data, π-π stacking of pyrazole backbones can be tailored effectively by energetic functionalities, thereby resulting in diversified energetic compounds. Among them, hydroxylammonium 4-amino-3,5-dinitro-1H-pyrazol-1-olate and dipotassium N,N'-(3,5-dinitro-1H-pyrazol-1,4-diyl)dinitramidate, with unique face-to-face π-π stacking, can be potentially used as a high-performance explosive and an energetic oxidizer, respectively...
October 20, 2016: Angewandte Chemie
Kota Sasaki, Tomohiro Ito, Hirotada G Fujii, Shingo Sato
The hybrid compounds 1-5 comprised of five nitroxides with ibuprofen were synthesized and their reduction rate for ascorbic acid (AsA) and methyl radicals were measured in comparison with 3-hydroxy-tetramethylpyrrolidine-1-oxyl (PROXYL) 6. The rate constants in reduction reaction with 200-fold excess of AsA were determined in following order: 1 (0.42±0.06), 3 (0.17±0.06), 2 (0.10±0.05), and 6 (0.09±0.02 M(-1)s(-1)). The remaining two sterically shielded nitroxides 4 and 5 scarcely reacted with AsA. In the reaction with the more reactive methyl radicals, produced by 200-fold excess of Fenton's reagent, the reduction rates of 2, 4, and 5 were in the following decreasing order: 2 (1...
2016: Chemical & Pharmaceutical Bulletin
Yoshihiro Shimoyama, Tomoya Ishizuka, Hiroaki Kotani, Yoshihito Shiota, Kazunari Yoshizawa, Kaoru Mieda, Takashi Ogura, Toshihiro Okajima, Shunsuke Nozawa, Takahiko Kojima
Proton-coupled electron-transfer oxidation of a Ru(II) -OH2 complex, having an N-heterocyclic carbene ligand, gives a Ru(III) -O(.) species, which has an electronically equivalent structure of the Ru(IV) =O species, in an acidic aqueous solution. The Ru(III) -O(.) complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru-O bond showed a lower-energy Raman scattering at 732 cm(-1) and the Ru-O bond length was estimated to be 1...
October 6, 2016: Angewandte Chemie
Inae Jang, Sun Young Lee, Song Hwangbo, Dukjin Kang, Hookeun Lee, Hugh I Kim, Bongjin Moon, Han Bin Oh
The present study demonstrates that one-step peptide backbone fragmentations can be achieved using the TEMPO [2-(2,2,6,6-tetramethyl piperidine-1-oxyl)]-assisted free radical-initiated peptide sequencing (FRIPS) mass spectrometry in a hybrid quadrupole time-of-flight (Q-TOF) mass spectrometer and a Q-Exactive Orbitrap instrument in positive ion mode, in contrast to two-step peptide fragmentation in an ion-trap mass spectrometer (reference Anal. Chem. 85, 7044-7051 (30)). In the hybrid Q-TOF and Q-Exactive instruments, higher collisional energies can be applied to the target peptides, compared with the low collisional energies applied by the ion-trap instrument...
September 29, 2016: Journal of the American Society for Mass Spectrometry
Imre Farkas, Csaba Vastagh, Erzsébet Farkas, Flóra Bálint, Katalin Skrapits, Erik Hrabovszky, Csaba Fekete, Zsolt Liposits
Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM-5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R...
2016: Frontiers in Cellular Neuroscience
Yuan Yuan Ji, Yan Jun Ma, Jian Wen Wang
Hypocrellin B (HB), a natural perylenequinone pigment, has been successfully employed in the photodynamic therapy (PDT) in a variety of human cancer cells due to its high singlet oxygen yield. To investigate the generation of nitric oxide (NO) and its role on cancer cell death induced by PDT, we used human hepatocellular carcinoma (HepG2) cells and HB as a photosensitizer. HB/light treatment decreased the growth of HepG2 cells in a dose-dependent manner with an IC50 of 3.10μM, activated caspase-3, -9 and induced apoptosis in HepG2 cells...
October 2016: Journal of Photochemistry and Photobiology. B, Biology
Jian Luo, Jian Zhang
A metal-free protocol to generate phthalimide-N-oxyl (PINO) radicals from N-hydroxyphthalimide (NHPI) via a photoinduced proton-coupled electron transfer process is reported. Using donor-substituted aromatic ketones, such as 4,4'-bis(diphenylamino)benzophenone (DPA-BP), PINO radicals are efficiently produced and subsequently utilized to functionalize olefins to afford a new class of alkyl hydroperoxides. The DPA-BP/NHPI/O2 photocatalytic system exhibits high efficiency toward the aerobic oxidation of β-O-4 lignin models...
October 7, 2016: Journal of Organic Chemistry
Yuanyuan Yu, Qiang Wang, Jiugang Yuan, Xuerong Fan, Ping Wang
This study demonstrated a new enzymatic methodology to graft β-cyclodextrin onto wool. The primary hydroxyl groups in β-cyclodextrin were oxidized to aldehyde groups using laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), which reacted with the amino groups of wool to form Schiff bases. The effects of treatment conditions (treatment temperature, laccase dosage, TEMPO dosage, treatment time) on the aldehyde and carboxyl contents in β-cyclodextrin were studied. FTIR spectrum of oxidized β-cyclodextrin showed the presence of aldehyde and carboxyl groups...
November 20, 2016: Carbohydrate Polymers
Yoko Hase, Juntaro Seki, Tohru Shiga, Fuminori Mizuno, Hidetaka Nishikoori, Hideki Iba, Kensuke Takechi
A novel indirect charging system that uses a redox mediator was demonstrated for Li-O2 batteries. 4-Methoxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl (MeO-TEMPO) was applied as a mediator to enable the oxidation of Li2O2, even though Li2O2 is electrochemically isolated. This system promotes the oxidation of Li2O2 without parasitic reactions attributed to electrochemical charging and reduces the charging time.
October 6, 2016: Chemical Communications: Chem Comm
Svyatoslav E Tolstikov, Evgeny V Tretyakov, Dmitry E Gorbunov, Irina F Zhurko, Matvey V Fedin, Galina V Romanenko, Artem S Bogomyakov, Nina P Gritsan, Dmitry G Mazhukin
It was shown that dipole-stabilized paramagnetic carbanion lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide can be attached in a nucleophilic manner to either isolated or conjugated aldonitrones of the 2,5-dihydroimidazole 3-oxide and 2H-imidazole 1-oxide series to afford adducts the subsequent oxidation of which leads to polyfunctional mono- and diradicals. According to XRD, at least two polymorphic modifications can be formed during crystallization of the resulting paramagnetic compounds, and for each of them, geometric parameters of the molecules are similar...
October 4, 2016: Chemistry: a European Journal
Keisuke Furukawa, Haruki Inada, Masatoshi Shibuya, Yoshihiko Yamamoto
The chemoselective oxidation of α-hydroxy acids to α-keto acids catalyzed by 2-azaadamantane N-oxyl (AZADO), a nitroxyl radical catalyst, is described. Although α-keto acids are labile and can easily release CO2 under oxidation conditions, the use of molecular oxygen as a cooxidant enables the desired chemoselective oxidation.
September 2, 2016: Organic Letters
Saber Ghasemi Karaj-Abad, Mojtaba Abbasian, Mehdi Jaymand
For the first time, nitroxide-mediated polymerization (NMP) was used for synthesis of graft and block copolymers using cellulose (Cell) as a backbone, and polystyrene (PSt) and poly(methyl metacrylate) (PMMA) as the branches. For this purpose, Cell was acetylated by 2-bromoisobutyryl bromide (BrBiB), and then the bromine group was converted to 4-oxy-2,2,6,6-tetramethylpiperidin-1-oxyl group by a substitution nucleophilic reaction to afford a macroinitiator (Cell-TEMPOL). The macroinitiator obtained was subsequently used in controlled graft and block copolymerizations of St and MMA monomers to yield Cell-g-PSt and Cell-g-(PMMA-b-PSt)...
November 5, 2016: Carbohydrate Polymers
Bianca Hemmeryckx, Philipp Hohensinner, Melissa Swinnen, Ward Heggermont, Johann Wojta, Henri Roger Lijnen
Bmal1 (brain and muscle ARNT-like protein-1) deficient (Bmal1) mice prematurely age due to an increased reactive oxygen species (ROS) production. These mice also show a decline in cardiac function with age. We investigated whether an anti-oxidant treatment can ameliorate the declining cardiac function in prematurely aged Bmal1 mice. Male Bmal1 and wild-type (Bmal1) mice were exposed for 15 weeks to a high fat and high cholesterol diet with or without the anti-oxidant 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL; 5 mmol/l; in drinking water during the last 10 weeks)...
August 4, 2016: Journal of Cardiovascular Pharmacology
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