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

Area of Science:

• Plasma Medicine
• Biochemistry
• Reactive Oxygen Species (ROS) Quantification

Background:

• Non-thermal plasma (NTP) devices produce ROS and reactive nitrogen species at near-physiological temperatures.
• Preclinical studies show NTP's potential in wound healing, disinfection, and cancer therapy.
• The impact of biocompatible reducing agents on NTP-induced ROS in liquid phases remains underquantified.

Purpose of the Study:

• To stoichiometrically quantitate key ROS (hydroxyl radical, singlet oxygen, superoxide, hydrogen peroxide) generated by NTP.
• To investigate the scavenging effects of antioxidants, including l-ascorbate (Asc), (-)-epigallocatechin gallate (EGCG), and α-tocopherol, on NTP-induced ROS.
• To elucidate the role of Asc/l-dehydroascorbate (DHA) redox cycling in modulating NTP's biological effects.

Main Methods:

• Electron paramagnetic resonance spectroscopy was used for hydroxyl radical (^●OH) quantification with a spin-trapping probe.
• Fluorescent and luminescent probes were employed to measure singlet oxygen (¹O₂), superoxide (O₂^-), and hydrogen peroxide (H₂O₂).
• Experiments were conducted with varying concentrations of antioxidants in liquid phases, including Chelex-treated water.

Main Results:

• Asc (50 μM) significantly scavenged ^●OH; EGCG and α-tocopherol were effective at 250 μM.
• Asc (100 μM) significantly scavenged O₂^- and H₂O₂.
• DHA degraded H₂O₂ but did not quench ^●OH or O₂^-. EGCG effectively scavenged ¹O₂, O₂^-, and H₂O₂ in Chelex-treated water.

Conclusions:

• The redox cycling of Asc/DHA and DHA metabolites are critical factors influencing NTP applications in biological systems.
• Antioxidants like EGCG significantly alter the outcome of NTP exposure by reducing ROS.
• Further research into ROS-biomolecule interactions is necessary to optimize NTP's therapeutic potential.