L-Dehydroascorbate efficiently degrades non-thermal plasma-induced hydrogen peroxide

Non-thermal plasma (NTP) devices generate reactive oxygen species (ROS) and reactive nitrogen species, such as singlet oxygen (O-1(2)), superoxide ((OH)-O-center dot), hydroxyl radical ((center dot OH)) hydrogen peroxide (H2O2), ozone, and nitric oxide at near-physiological temperature. In preclinical studies, NTP promotes blood coagulation, wound healing with disinfection, and selective killing of cancer cells. Although these biological effects of NTP have been widely explored, the stoichiometric quantitation of ROS in the liquid phase has not been performed in the presence of biocompatible reducing agents, which may modify the final biological effects of NTP. Here, we utilized electron paramagnetic resonance spectroscopy to quantitate (OH)-O-center dot, using a spin-trapping probe 5,5-dimethyl-1-pyrroline-N-oxide; O-1(2), using a fluorescent probe; and O-2(-) and H2O2, using luminescent probes, after NTP exposure in the presence of antioxidants. t-ascorbate (Asc) at 50 mu M concentration (physiological concentration in serum) significantly scavenged (OH)-O-center dot, whereas (-)-epigallocatechin gallate (EGCG) and alpha-tocopherol were also effective at performing scavenging activities at 250 mu M concentrations. Asc significantly scavenged O-2(-) and H2O2 at 100 mu M. L-Dehydroascorbate (DHA), an oxidized form of Asc, degraded H2O2, whereas it did not quench (OH)-O-center dot or O-2(-), which are sources of H2O2. Furthermore, EGCG efficiently scavenged NTP-induced O-1(2), O-2(-), and H2O2 in Chelex-treated water. These results indicate that the redox cycling of Asc/DHA and metabolites of DHA are important to be considered when applying NTP to cells and tissues. Additionally, ROS-reducing compounds, such as EGCG, affect the outcome. Further studies are warranted to elucidate the interaction between ROS and biomolecules to promote the medical applications of NTP.

Automated summary

The study utilized electron paramagnetic resonance spectroscopy to quantify different reactive oxygen species generated by NTP in the presence of antioxidants, demonstrating significant scavenging effects of antioxidants on reactive oxygen species. The importance of redox cycling of Asc/DHA and metabolites of DHA, as well as the impact of ROS-reducing compounds like EGCG, were highlighted in the study for NTP application in cells and tissues. Further research is needed to explore the interaction between ROS and biomolecules to enhance the medical applications of NTP.