Aminonitrone-N-hydroxyaminoimine tautomeric equilibrium in the series of 1-hydroxy-2-imidazolines
摘要:
A series of 2-substituted 1-hydroxy-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazoles have been synthesized. Various effects on the state of the aminonitrone-N-hydroxyaminoimine tautomeric equilibrium, including solvent effects and substituent effect in the 2 position of heterocycle, have been studied. (C) 2004 Elsevier B.V. All rights reserved.
nitroxide derivatives 4a-h. A lead compound 4f was discovered based on Ach-induced vascorelaxation assay. Further chemical modification based on this scaffold provided a new series of 2-substituted phenylnitronyl nitroxide derivatives 6a-s. The newly synthesized compounds 6a-s possess improved radical scavenger's activity based on PC12 cell survival assay. Compounds 6g,n,o, and s are some of the most
为了开发具有增强的自由基清除剂性能的更有效的小分子,我们设计并合成了一系列硝酰基硝基氧衍生物4a-h。基于Ach诱导的血管舒张测定法发现了前导化合物4f。基于该支架的进一步化学修饰提供了一系列新的2-取代的苯基亚硝酰基硝基氧化物衍生物6a-s。基于PC12细胞存活测定法,新合成的化合物6a-s具有改善的自由基清除剂的活性。就NO,H(2)O(2)和OH的清除能力而言,化合物6g,n,o和s是一些最有效的化合物。2-取代的苯基亚硝基硝基氮氧化物具有较高的自由基清除活性,带有给电子基团(EDG)。相比之下,吸电子基团(EWG)引入芳环导致其自由基清除活性急剧下降。这些结果表明,芳香环的给电子基团(EDG)可能是影响这些化合物清除自由基行为的重要因素,清除自由基的能力很大程度上取决于苯环的位置和电子性质。取代基。新型的2-取代的硝酰基氮氧化物的增强的自由基清除能力可能是对抗ROS(活性氧)/ R
Preparation and Characterization of New Chiral Nitronyl Nitroxides Bearing a Stereogenic Center in the Imidazolyl Framework
synthetic procedure for opticallyactive and racemic α-nitronyl nitroxides (α-NNs) having a stereogenic center at the 4-position of the imidazolyl ring is described. This procedure consists of (1) the synthesis of a dissymmetric vic-dinitro compound by Kornblum reaction, (2) the enantiomeric resolution of the racemate by a diastereomer method for obtaining the opticallyactive sample, (3) the quick reduction
Provided herein are isolated laccase enzymes and nucleic acids encoding them. Also provided are mediators for laccase reactions. Also provided herein are methods for using laccases to oxidize lignins and other phenolic and aromatic compounds, such as for bio-bleaching and decolorization of wood pulp under high temperature and pH conditions to facilitate a substantial reduction in use of bleaching chemicals, as well as for treatment of fibers.
Provided herein are isolated laccase enzymes and nucleic acids encoding them. Also provided are mediators for laccase reactions. Also provided herein are methods for using laccases to oxidize lignins and other phenolic and aromatic compounds, such as for bio-bleaching and decolorization of wood pulp under high temperature and pH conditions to facilitate a substantial reduction in use of bleaching chemicals, as well as for treatment of fibers.
Provided herein are isolated laccase enzymes and nucleic acids encoding them. Also provided are mediators for laccase reactions. Also provided herein are methods for using laccases to oxidize lignins and other phenolic and aromatic compounds, such as for bio-bleaching and decolorization of wood pulp under high temperature and pH conditions to facilitate a substantial reduction in use of bleaching chemicals, as well as for treatment of fibers.