Tetrachloroaurate (III)–induced Oxidation Increases Non-thermal Plasma-induced Oxidative Stress

Non-thermal plasma (NTP) devices have been explored for medical applications. NTP devices discharge electrons, positive ions, ultraviolet, and reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as the hydroxyl radical (●OH), singlet oxygen (1O2), superoxide (O2●−), hydrogen peroxide (H2O2), ozone, and nitric oxide, at near-physiological temperature. At preclinical stages or in human clinical trials, NTP promotes blood coagulation, eradication of bacterial, viral, and biofilm-related infections, wound healing, and cancer cell death. Here, we observed that ferric, vanadium, and gold(III) ions, measured by 2-thiobarbituric acid-reactive substances (TBARS) in combination with NTP exposure, significantly elevated lipid peroxidation. Using 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) as a spin probe in electron paramagnetic resonance (EPR), we observed that tetrachloroaurate (III) yielded an M4PO-X spin adduct. Tetrachloroaurate-induced oxidation was attenuated efficiently by reduced (GSH) and oxidized glutathione (GSSG), while glycine (Gly) and L-glutamate (Glu), components of GSH, were ineffective. Furthermore, GSH and GSSG efficiently suppressed tetrachloroaurate-induced lipid peroxidation, while Gly and Glu were ineffective in suppressing TBARS elevation. These results indicate that tetrachloroaurate-induced oxidation is attenuated by GSH as well as GSSG. Further studies are warranted to elucidate the redox reactions between metal ions and biomolecules to advance the clinical application of NTP.

•BMPO-OOH Spin-Adduct as a Model for Study of Decomposition of Organic Hydroperoxides and the Effects of Sulfide/Selenite Derivatives. An EPR Spin-Trapping Approach

Lipid hydroperoxides play an important role in various pathophysiological processes. Therefore, a simple model for organic hydroperoxides could be helpful to monitor the biologic effects of endogenous and exogenous compounds. The electron paramagnetic resonance (EPR) spin-trapping technique is a useful method to study superoxide (O2•−) and hydroxyl radicals. The aim of our work was to use EPR with the spin trap 5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO), which, by trapping O2•− produces relatively stable •BMPO-OOH spin-adduct, a valuable model for organic hydroperoxides. We used this experimental setup to investigate the effects of selected sulfur/selenium compounds on •BMPO-OOH and to evaluate the antioxidant potential of these compounds. Second, using the simulation of time-dependent individual BMPO adducts in the experimental EPR spectra, the ratio of •BMPO-OH/•BMPO-OOH—which is proportional to the transformation/decomposition of •BMPO-OOH—was evaluated. The order of potency of the studied compounds to alter •BMPO-OOH concentration estimated from the time-dependent •BMPO-OH/•BMPO-OOH ratio was as follows: Na2S4 > Na2S4/SeO32− > H2S/SeO32− > Na2S2 ~Na2S2/SeO32− ~H2S > SeO32− ~SeO42− ~control. In conclusion, the presented approach of the EPR measurement of the time-dependent ratio of •BMPO-OH/•BMPO-OOH could be useful to study the impact of compounds to influence the transformation of •BMPO-OOH.

Theoretical studies on the spin trapping of the 2-chloro-5-hydroxy-1,4-benzoquinone radical by 5,5-dimethyl-1-pyrroline N-oxide (DMPO): the identification of the C–O bonding spin adduct

The C–O bonding spin adduct has been identified in the spin trapping of 2-chloro-5-hydroxy-1,4-benzoquinone radical by DMPO.

Estimation of the Postmortem Duration of Mouse Tissue by Electron Spin Resonance Spectroscopy

Electron spin resonance (ESR) method is a simple method for detecting various free radicals simultaneously and directly. However, ESR spin trap method is unsuited to analyze weak ESR signals in organs because of water-induced dielectric loss (WIDL). To minimize WIDL occurring in biotissues and to improve detection sensitivity to free radicals in tissues, ESR cuvette was modified and used with 5,5-dimethtyl-1-pyrroline N-oxide (DMPO). The tissue samples were mouse brain, hart, lung, liver, kidney, pancreas, muscle, skin, and whole blood, where various ESR spin adduct signals including DMPO-ascorbyl radical (AsA∗), DMPO-superoxide anion radical (OOH), and DMPO-hydrogen radical (H) signal were detected. Postmortem changes in DMPO-AsA∗and DMPO-OOH were observed in various tissues of mouse. The signal peak of spin adduct was monitored until the 205th day postmortem. DMPO-AsA∗in liver (y=113.8–40.7 log (day),R1=-0.779,R2=0.6,P<.001) was found to linearly decrease with the logarithm of postmortem duration days. Therefore, DMPO-AsA∗signal may be suitable for detecting an oxidation stress tracer from tissue in comparison with other spin adduct signal on ESR spin trap method.