Diabetic patients frequently encounter ketosis that is characterized by the breakdown of lipids with the consequent accumulation of ketone bodies. Several studies have demonstrated that reactive species are likely to induce tissue damage in diabetes, but the role of the ketone bodies in the process has not been fully investigated. In this study, electron paramagnetic resonance (EPR) spectroscop...

The limitation of hydroxamate ester as a chiral Lewis acid coordination moiety was first shown in an intermolecular reaction involving a radical addition and sequential allylation processes. Next, the effect of hydroxamate ester was studied in the cascade addition-cyclization-trapping reaction of substrates with a carbon-carbon triple bond as a radical acceptor. When substrates with a methacryl...

Rate constants for the rearrangement of 1-bicyclo[3.1.0]hexanylmethyl radical (2) to 3-methylenecyclohexenyl radical (3) and 2-methylenecyclopentyl-1-methyl radical (1) were measured using the PTOC-thiol competition method. The ring-expansion pathway is described by the rate equation, log(k/s-1) = (12.5 +/- 0.1) - (4.9 +/- 0.1)/theta; the non-expansion pathway is described by log(k/s-1) = (11.9...

We have used spin-trapping techniques to identify radical species formed during the NADPH-stimulated peroxidation of rat hepatic microsomes. Using 5,5-dimethyl-1-pyrroline-1-oxide, we have confirmed the presence of substantial quantities of superoxide but found evidence for the formation of only small quantities of hydroxyl radical. Use of the spin traps N-tert-butyl-alpha-4-pyridylnitrone-1-ox...

Autoxidation is a set of spontaneous oxygen-mediated radical reactions common to degradation processes all hydrocarbon-based materials. In this work, EPR (electron paramagnetic resonance) spin-trapping technique was used study species involved in the autoxidation sample synthetic base oil. A polyalphaolefin oil aged at 140°C presence oxygen and difference tendency generate between non-aged samp...

Herein we describe our efforts to elucidate the key mechanistic aspects of the previously reported enantioselective photochemical α-alkylation of aldehydes with electron-poor organic halides. The chemistry exploits the potential of chiral enamines, key organocatalytic intermediates in thermal asymmetric processes, to directly participate in the photoexcitation of substrates either by forming a ...

Human neutrophils generate oxygen reduction products as a consequence of membrane interactions with a number of stimuli. One oxygen-centered free radical (superoxide) has been unequivocally shown to result from this "respiratory burst," and some experimental evidence for another (hydroxyl radical) has been published, although debate remains as to its significance. The role of phagocyte-derived ...

Primary free radical formation in trehalose dihydrate single crystals X-irradiated at 10 K was investigated at the same temperature using X-band Electron Paramagnetic Resonance (EPR), Electron Nuclear Double Resonance (ENDOR) and ENDOR-induced EPR (EIE) techniques. The ENDOR results allowed the unambiguous determination of six proton hyperfine coupling (HFC) tensors. Using the EIE technique, th...

Endotoxemia is associated with alcoholic liver diseases; however, the effect of endotoxin on the oxidation of ethanol is not known. We tested the hypothesis that endotoxin treatment enhances hepatic ethanol radical production. The generation of free radicals by the liver was studied with spin-trapping technique utilizing the primary trap ethanol (0.8 g/kg) and the secondary trap α-(4-pyridyl-1-...