40936-05-8Relevant academic research and scientific papers
Generation of free radicals by emodic acid and its [D-Lys6]GnRH-conjugate
Rahimipour, Shai,Bilkis, Izhak,Peron, Vincent,Gescheidt, Georg,Barbosa, Frederique,Mazur, Yehuda,Koch, Yitzhak,Weiner, Lev,Fridkin, Mati
, p. 226 - 236 (2001)
In an attempt to develop an efficient chemotherapeutic agent targeted at malignant cells that express receptors to gonadotropin releasing hormone (GnRH) we coupled [D-Lys6]GnRH covalently to an emodin derivative, i.e. emodic acid (Emo) to yield
Amidinoquinoxaline N-oxides as novel spin traps
Gruber, Nadia,Piehl, Lidia L.,De Celis, Emilio Rubin,Daz, Jimena E.,Garca, Mara B.,Stipa, Pierluigi,Orelli, Liliana R.
, p. 2724 - 2731 (2015/02/19)
A novel type of spin traps 1 derived from the pyrimidoquinoxaline N-oxide heterocyclic core is reported. EPR technique was used to evaluate their ability to trap methyl radicals generated in a Fenton reaction in the presence of DMSO. All the synthesized nitrones showed spin trapping properties and the corresponding nitroxides 2 were characterized by EPR. The novel spin traps showed remarkably persistent signals, as confirmed in a competition experiment with DMPO. The addition rate constants leading to the spin adducts (kadd) were determined, and very good correlations were found with steric and electronic parameters of the parent nitrones. The spin adducts decomposition rate constants (kdec) and the corresponding half-life times (t1/2) were also determined. DFT and MP2 calculations were used in order to rationalize the adducts hfcc and the structural factors influencing their addition and decomposition rates.
Gold nanoparticle-initiated free radical oxidations and halogen abstractions
Ionita, Petre,Conte, Marco,Gilbert, Bruce C.,Chechik, Victor
, p. 3504 - 3509 (2008/09/20)
We report on the use of EPR spectroscopy and spin trapping technique to detect free radical intermediates formed in the presence of gold nanoparticles. Phosphine- and amine-protected gold nanoparticles were found to initiate air oxidation of organic subst
High static pressure alters spin trapping rates in solution. Dependence on the structure of nitrone spin traps
Sueishi, Yoshimi,Yoshioka, Daisuke,Yoshioka, Chiharu,Yamamoto, Shunzo,Kotake, Yashige
, p. 896 - 901 (2007/10/03)
Using a competitive spin trapping method, relative spin trapping rates were quantified for various short-lived radicals (methyl, ethyl, and phenyl radicals). High static pressure was applied to the competitive spin-trapping system by employing high-pressure electron spin resonance (ESR) equipment. Under high pressure (490 bar), spin trapping rate constants for alkyl and phenyl radicals increased by 10 to 40%, and the increase was dependent on the structure of nitrone spin traps. A maximum increase was obtained when tert-butyl(4-pyridinylmethylene)amine N-oxide (4-POBN) was used as a spin trap. Activation volumes (ΔΔV?) for the two spin trapping reactions were calculated to be -17-(-9) cm3 mol -1 for the 4-POBN system. The Royal Society of Chemistry 2006.
New 2-Substituted Pyrroline-N-oxides: An EPR Solvent Study of the Radical Spin Adducts
Janzen, Edward G.,Zhang, Yong-Kang,Haire, D. Lawrence
, p. 711 - 720 (2007/10/02)
Ten substituted 5,5-dimethyl-1-pyrroline-N-oxides as well as the parent nitrene spin trap (DMPO) were prepared: 5,5-dimethyl-1-pyrroline-N-oxide, 2,5,5-trimethyl-1-pyrroline-N-oxide, 2-tert-butyl-5,5-dimethyl-1-pyrroline-N-oxide, 2-phenyl-5,5-dimethyl-1-pyrroline-N-oxide, 2-d5-phenyl-5,5-dimethyl-1-pyrroline-N-oxide, 2-phenyl-5,5-dimethyl-1-pyrroline-N-oxide-nitronyl-13C, 2-(4-fluorophenyl)-5,5-dimethyl-1-pyrroline-N-oxide, 2-(4-chlorophenyl)-5,5-dimethyl-1-pyrroline-N-oxide, 2-(4-tert-butylphenyl)-5,5-dimethyl-1-pyrroline-N-oxide, 2-(4-methylphenyl)-5,5-dimethyl-1-pyrroline-N-oxide and 2-(2-methylphenyl)-5,5-dimethyl-1-pyrroline-N-oxide.Analytical (i.e.EPR-grade) samples of these novel cyclic nitrones were obtained and characterized by (among other methods) 1H NMR spectroscopy.Reduction of DMPO and these various 2-substituted cyclic nitrones gave the corresponding cyclic N,N-dialkylhydroxylamines, whose structure and conformations were also analyzed by 1H NMR spectroscopy.Air oxidation of these cyclic N,N-dialkylhydroxylamines provided access to the EPR spectra of the hydrogen, methyl, tert-butyl, phenyl, d5-phenyl, nitronyl-13C-phenyl, 4-fluorophenyl, 4-chlorophenyl, 4-tert-butylphenyl, 4-methylphenyl and 2-methylphenyl cyclic aminoxyl (pyrrolidine N-oxyl nitroxide) radical spin adducts of DMPO.The 14N, 13C (where applicable) and 1H hyperfine splitting constants of these aminoxyl adducts in ten solvents of widely different polarities (e.g., hexane to water) were measured and the solvent effect on these parameters was evaluated.It was found that for the various 2-substituted DMPO-type apin adducts both the nitrogen and β-hydrogen EPR hyperfine splittings correlated linearly (r2 >/= 0.90) with typical solvent polarity parameters such as ET(30).The correlation between the nitrogen and β-hydrogen hyperfine splitting constants were even more linear (r2 >/= 0.97). - Keywords: electron paramagnetic resonance NMR 1H, 14N and 13C hyperfine splittings Spin traps Spin adducts Nitrones (1-pyrroline-N-oxides)
