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Paolo Pirovano, Abigail R Berry, Marcel Swart, Aidan R McDonald
The reaction of a NiII complex and meta-chloroperoxybenzoic acid (m-CPBA) resulted in the formation of a long-lived NiIII-chlorobenzoate complex that is a capable hydrocarbon oxidant. Analysis of the post-reaction decay products showed the formation of oxidised derivatives of the supporting ligand (a benzoxazine), and heterolytic O-O bond scission in m-CPBA. This evidence indicates formation of a more potent transient NiIII-oxyl species, which was further supported by DFT calculations.
December 6, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
D David Jebaraj, Hideo Utsumi, A Milton Franklin Benial
Low frequency electron spin resonance studies were performed for 2 mM concentration of deuterated permeable and impermeable nitroxyl spin probes, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy in pure water and various concentrations of corn oil solution. The electron spin resonance parameters such as, the line width, hyperfine coupling constant, g-factor, rotational correlation time, permeability and partition parameter were estimated. The broadening of line width was observed for nitroxyl radicals in corn oil mixture...
December 4, 2017: Magnetic Resonance in Chemistry: MRC
Takayuki Kamiya, Taiji Nagaoka, Tsuneaki Omae, Shinji Ono, Shinichi Otani, Akitoshi Yoshida
Purpose: To investigate whether benzo(e)pyrene (B(e)P), a toxicant in cigarette smoke, affects the endothelium-dependent nitric oxide (NO)-induced vasodilation of the retinal arterioles, and whether oxidative stress, distinct protein kinase signaling pathways, and endoplasmic reticulum (ER) stress are associated with the B(e)P-induced effect on the retinal arterioles. Methods: In this in vitro study, porcine retinal arterioles were isolated, cannulated, and pressurized without flow...
November 1, 2017: Investigative Ophthalmology & Visual Science
Li Zou, Valerie Linck, Yu-Jia Zhai, Laura Galarza-Paez, Linda Li, Qiang Yue, Otor Al-Khalili, Hui-Fang Bao, He-Ping Ma, Tiffany L Thai, Jundong Jiao, Douglas C Eaton
It has been suggested that voltage-dependent anion channels (VDACs) control the release of superoxide from mitochondria. We have previously shown that reactive oxygen species (ROS) such as superoxide (O2-) and hydrogen peroxide (H2O2) stimulate epithelial sodium channels (ENaCs) in sodium-transporting epithelial tissue including cortical collecting duct (CCD) principal cells. Therefore, we hypothesized that VDACs could regulate ENaC by modulating cytosolic ROS levels. Herein, we find that VDAC3-knockout(KO) mice can maintain normal salt and water balance on low-salt and high-salt diets...
November 27, 2017: Journal of Biological Chemistry
Yuanfang Kong, Kediliya Wumaier, Yingze Liu, Chunhui Jiang, Shuai Wang, Lingyan Liu, Weixing Chang, Jing Li
A novel and efficient Cu(OAc)2 -catalyzed hydroamination cyclization and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidative dehydrogenation cascade reaction of homopropargylic amines has been developed. A library of 1,2-disubstituted pyrrole derivatives were obtained in good-to-high yields in one pot with no step-by-step feeding process. This reaction involved TEMPO playing dual roles as both an oxidative dehydrogenation reagent and a ligand. An insight into the reaction mechanism was obtained by using several analytical determination methods...
November 27, 2017: Chemistry, An Asian Journal
Feng Wang, Peng Gao, Ling Guo, Ping Meng, Yuexing Fan, Yongbin Chen, Yanyun Lin, Guozhen Guo, Guirong Ding, Haibo Wang
OBJECTIVES: To search for more effective radiation protectors with minimal toxicity, a water-soluble nitroxides Acetamido-Tempol (AA-Tempol) was evaluated for potential radioprotective properties in HUVEC cells (Human Umbilical Vein Endothelial cell line). METHODS: To study the anti-radiation effect of AA-Tempol in cell culture, the viability of irradiated HUVEC cells using a clonogenic survival assay was examined. The anti-apoptosis effects of AA-Tempol using Annexin V/propidium iodide staining in a flow cytometry assay was also evaluated...
March 24, 2017: Environmental Health and Preventive Medicine
Zeping Shao, Zhonghui Han, Jinhui Zhang, Yan Zhang, Shuo Wang
BACKGROUND: Heterocyclic aromatic amines (HAAs) have been considered as carcinogenic and mutagenic chemicals generated during thermal processing of protein-rich foods which can be inhibited by some flavonoids. And free radical scavenging is a major characteristic of flavonoids. RESULTS: The half maximal inhibitory concentration (IC50 ) values of nine flavonoids were determined by evaluating their capacity to inhibit 2-amino-3,8-dimethyl-imidazo[4,5-f]-quinoxaline (MeIQx) and 2-amino-3,7,8-trimethyl-imidazo[4,5-f]-quinoxaline (7,8-DiMeIQx) formation in a model system...
November 21, 2017: Journal of the Science of Food and Agriculture
Ryunosuke Funahashi, Yuko Ono, Reina Tanaka, Morihiko Yokoi, Kunihiko Daido, Toru Inamochi, Tsuguyuki Saito, Yoshiki Horikawa, Akira Isogai
Most commercially available plant celluloses, such as kraft pulps and cotton celluloses, have so-called leveling-off degrees of polymerization (LODPs) when subjected to dilute acid hydrolysis. The formation of LODPs is hypothesized to be caused by disordered regions that are present periodically along each cellulose microfibril in plant celluloses. Here, we prepared never-dried wood cellulose, and wood celluloses at different drying stages, and subjected them to dilute acid hydrolysis. The viscosity average degrees of polymerization (DPv) of the wood celluloses decreased in DPv with increasing dilute acid-hydrolysis times...
November 13, 2017: International Journal of Biological Macromolecules
Mizuki Nakamura, Sayaka Shibata, Toshihide Yamasaki, Megumi Ueno, Ikuo Nakanishi, Ken-Ichiro Matsumoto, Tadashi Kamada, Ken-Ichi Yamada, Ichio Aoki
The effect of different static magnetic field strengths, 1 T or 7 T, on the quality of nitroxyl radical-based magnetic resonance redox imaging (MRRI) was examined. A stable nitroxyl radical, 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (MC-PROXYL), was used as a T1 contrast agent. Phantoms and animals were scanned at 1 T and 7 T using a similar gradient echo sequence. The quality of T1-weighted images and susceptibility of T1-weighted signals were compared. The nitroxyl radical-based T1-weighted signal enhancement ratio was higher at 1 T compared with at 7 T when the identical phantom was scanned using a similar gradient echo sequence...
2017: American Journal of Translational Research
Helmut Schwarz, Sason Shaik, Jilai Li
This Perspective discusses a story of one molecule (methane), a few metal-oxide cationic clusters (MOCCs), dopants, metal-carbide cations, oriented-electric fields (OEFs), and a dizzying mechanistic landscape of methane activation! One mechanism is hydrogen atom transfer (HAT), which occurs whenever the MOCC possesses a localized oxyl radical (M-O(•)). Whenever the radical is delocalized, e.g., in [MgO]n(•+) the HAT barrier increases due to the penalty of radical localization. Adding a dopant (Ga2O3) to [MgO]2(•+) localizes the radical and HAT transpires...
November 17, 2017: Journal of the American Chemical Society
Yuma Ishida, Yuka Okamoto, Yuta Matsuoka, Arisa Tada, Jindaporn Janprasit, Mayumi Yamato, Noppawan Phumala Morales, Ken-Ichi Yamada
Oxidized low density lipoprotein (Ox-LDL) is implicated in a variety of oxidative diseases. To clarify the mechanisms involved and facilitate the investigation of therapeutics, we previously developed a detection method for lipid-derived radicals using the fluorescent probe 2,2,6-trimethyl-6-pentyl-4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)piperidine-1-oxyl (NBD-Pen). In this study, NBD-Pen was used to detect lipid-derived radicals in Ox-LDL from in vitro and in vivo samples using an iron overloaded mouse model...
October 28, 2017: Free Radical Biology & Medicine
Jiajia Ma, Xiulan Xie, Eric Meggers
Here we report a visible-light-induced asymmetric three-component fluoroalkylation reaction scheme catalyzed by a stereogenic-at-metal rhodium-based Lewis acid. The photoredox process is mediated by the inexpensive, commercially available organic photoredox mediator 4,4'-difluorobenzil, which upon activation by visible light induces the generation of perfluoroalkyl radicals from their respective sulfinates via single electron transfer (SET) oxidation. The fluorinated radicals are subsequently trapped by electron-rich C-C double bonds to deliver α-oxyl carbon-centered radical species, followed by a stereocontrolled reaction with acceptor-substituted alkenes...
November 6, 2017: Chemistry: a European Journal
Hiroshi Asanuma, Shoji Sanada, Toru Yoshitomi, Hideyuki Sasaki, Hiroyuki Takahama, Madoka Ihara, Hiroko Takahama, Yoshiro Shinozaki, Hidezo Mori, Masanori Asakura, Atsushi Nakano, Masaru Sugimachi, Yoshihiro Asano, Tetsuo Minamino, Seiji Takashima, Yukio Nagasaki, Masafumi Kitakaze
PURPOSE: Although nitroxyl radicals such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) scavenge free radicals, their short half-life and considerable side effects such as systemic hypotension and bradycardia have limited their clinical application. Since a radical-containing nanoparticle (RNP) delivers nitroxyl radicals with a prolonged half-life specific to ischemic hearts, we investigated whether RNPs reduce infarct size without the occurrence of substantial side effects and whether nitric oxide (NO) contributes to the cardioprotective effects of RNPs...
November 3, 2017: Cardiovascular Drugs and Therapy
Ya-Qun Zhou, Dai-Qiang Liu, Shu-Ping Chen, Jia Sun, Xue-Rong Zhou, Heike Rittner, Wei Mei, Yu-Ke Tian, Hui-Xian Zhang, Fei Chen, Da-Wei Ye
Cancer-induced bone pain (CIBP) is a frequent complication in patients suffering from bone metastases. Previous studies have demonstrated a pivotal role of reactive oxygen species (ROS) in inflammatory and neuropathic pain, and ROS scavengers exhibited potent antinociceptive effect. However, the role of spinal ROS remains unclear. In this study, we investigated the analgesic effect of two ROS scavengers in a well-established CIBP model. Our results found that intraperitoneal injection of N-tert-Butyl-α-phenylnitrone (PBN, 50 and 100mg/kg) and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol, 100 and 200mg/kg) significantly suppressed the established mechanical allodynia in CIBP rats...
October 16, 2017: Redox Biology
Ojodomo J Achadu, Tebello Nyokong
Graphitic carbon nitride quantum dots (gCNQDs) when alone or containing embedded 4-amino-2,2,6,6-tetramethyl(piperidin-1-yl)oxyl) (4-AT) (gCNQDs-4-AT(embedded)) were synthesized via low temperature in situ one-pot process from diaminomaleonitrile (DAMN). The blue emission of both gCNQDs and gCNQDs-4-AT were excitation wavelength-dependent with very high fluorescence quantum yields of 43 and 51%, respectively. Further, the gCNQDs were covalently linked to 4-AT via an amide bond to give (gCNQDs-4-AT (linked))...
October 23, 2017: Analytica Chimica Acta
Lijuan Niu, Jian Yu, Weibiao Liao, Jihua Yu, Meiling Zhang, Mohammed M Dawuda
Osmotic stress is a major form of abiotic stress that adversely affects growth and development of plants and subsequently reduces yield and quality of crops. In this study, the effect of nitric oxide (NO) and calcium (Ca(2+)) on the process of adventitious rooting in cucumber (Cucumis sativus L.) under simulated osmotic stress was investigated. The results revealed that the effect of exogenous NO and Ca(2+) in promoting the development of adventitious roots in cucumber seedlings under simulated osmotic stress was dose-dependent, with a maximal biological response at 10 μM NO donor nitroprusside (SNP) or 200 μM Ca(2+)...
2017: Frontiers in Plant Science
Zhuhong Zhang, Zhen Ren, Si Chen, Xiaoqing Guo, Fang Liu, Lei Guo, Nan Mei
4-Methoxy-TEMPO, a derivative of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), is a stable nitroxide radical and is generally used in organic and pharmaceutical syntheses for the oxidation of alcohols. Previously, we reported the involvement of reactive oxygen species (ROS) and c-Jun N-terminal kinases (JNK) in TEMPO-induced apoptosis in mouse L5178Y cells. In this study, we investigated 4-methoxy-TEMPO induced toxicity in human HepG2 hepatoma cells and its underlying mechanisms. Treatments with 4-methoxy-TEMPO (0...
October 9, 2017: Archives of Toxicology
Meng Yang, Jing Xie, Zan Sun, Licun Li, Jean-Pascal Sutter
Ladder-type and chain 2p-3d-4f complexes based on a bridging nitronyl nitroxide radical, namely, [LnCu(hfac)5(NIT-Ph-p-OCH2trz)]·0.5C6H14 [Ln = Y (1a), Dy (1b)] and [LnCu(hfac)5(NIT-Ph-p-OCH2trz)] [Ln = Y (2a), Dy (2b); NIT-Ph-p-OCH2trz = 2-[4-[(1H-1,2,4-triazol-1-yl)methoxy]phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) have been successfully achieved through a one-pot reaction of the NIT-Ph-p-OCH2trz radical with Cu(hfac)2 and Ln(hfac)3·2H2O. Complexes 1a and 1b feature a ladder-like structure, where the rails are made of Ln(III) and Cu(II) ions alternatively bridged by nitronyl nitroxide and the triazole units while the NIT-Ph-p-OCH2trz moieties act as the rungs of the ladder...
November 6, 2017: Inorganic Chemistry
Zhanyong Li, Aaron W Peters, Ana E Platero-Prats, Jian Liu, Chung-Wei Kung, Hyunho Noh, Matthew R DeStefano, Neil M Schweitzer, Karena W Chapman, Joseph T Hupp, Omar K Farha
Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal-organic framework (MOF) NU-1000, have been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (<230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 followed by Co(II) ion deposition, yielding a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters...
October 16, 2017: Journal of the American Chemical Society
Zeyu Cao, Xingliang Duan, Ping Yao, Weiti Cui, Dan Cheng, Jing Zhang, Qijiang Jin, Jun Chen, Tianshan Dai, Wenbiao Shen
Metabolism of molecular hydrogen (H₂) in bacteria and algae has been widely studied, and it has attracted increasing attention in the context of animals and plants. However, the role of endogenous H₂ in lateral root (LR) formation is still unclear. Here, our results showed that H₂-induced lateral root formation is a universal event. Naphthalene-1-acetic acid (NAA; the auxin analog) was able to trigger endogenous H₂ production in tomato seedlings, and a contrasting response was observed in the presence of N-1-naphthyphthalamic acid (NPA), an auxin transport inhibitor...
October 3, 2017: International Journal of Molecular Sciences
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