On the Liquid Chemistry of the Reactive Nitrogen Species Peroxynitrite and Nitrogen Dioxide Generated by Physical Plasmas.

Giuliana Bruno,Jan-Wilm Lackmann,Michael Lalk,Kristian Wende,Thomas Von Woedtke,Sebastian Wenske

doi:10.3390/biom10121687

Abstract

Cold physical plasmas modulate cellular redox signaling processes, leading to the evolution of a number of clinical applications in recent years. They are a source of small reactive species, including reactive nitrogen species (RNS). Wound healing is a major application and, as its physiology involves RNS signaling, a correlation between clinical effectiveness and the activity of plasma-derived RNS seems evident. To investigate the type and reactivity of plasma-derived RNS in aqueous systems, a model with tyrosine as a tracer was utilized. By high-resolution mass spectrometry, 26 different tyrosine derivatives including the physiologic nitrotyrosine were identified. The product pattern was distinctive in terms of plasma parameters, especially gas phase composition. By scavenger experiments and isotopic labelling, gaseous nitric dioxide radicals and liquid phase peroxynitrite ions were determined as dominant RNS. The presence of water molecules in the active plasma favored the generation of peroxynitrite. A pilot study, identifying RNS driven post-translational modifications of proteins in healing human wounds after the treatment with cold plasma (kINPen), demonstrated the presence of in vitro determined chemical pathways. The plasma-driven nitration and nitrosylation of tyrosine allows the conclusion that covalent modification of biomolecules by RNS contributes to the clinically observed impact of cold plasmas.

Highlights

Reactive nitrogen and oxygen species (RNS/ROS) are unstable compounds prone to react rapidly with cellular molecules
This work studied the liquid chemistry of argon plasmas generated by the kINPen, with a special focus on reactive nitrogen species
Assuming that the liquid chemistry is the bridge between the gaseous plasma and biological systems, we looked for the impact of nitrogen species on the model biomolecule tyrosine

Summary

Introduction

Reactive nitrogen and oxygen species (RNS/ROS) are unstable compounds prone to react rapidly with cellular molecules In biological systems, they may be involved in redox signaling pathways (e.g., oxygen sensing, muscles and vascular physiology, immune defense, inflammatory processes) [1], mostly by covalently changing the structure of biomolecules such as lipids and proteins [2,3,4,5]. In addition to direct signaling events triggered by long-lived reactive species like H2O2, e.g., via peroxiredoxins, plasma-derived short-lived reactive species can covalently modify biomolecules in model systems [26,30,31,32,33,34,35] It remains to be clarified whether extracellularly modified molecules yield to intracellular physiological consequences or if only changes in cellular structures (e.g., cell membrane proteins) are relevant

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Conclusion