Decomposition and oxidation of methionine and tryptophan following irradiation with a nonequilibrium plasma jet and applications for killing cancer cells

Giichiro Uchida,Kosuke Takenaka,Takashi Suzuki,Tensho Suzuki,Yusuke Mino,Jun-Ichiro Ikeda,Yuichi Setsuhara

doi:10.1038/s41598-019-42959-4

Giichiro Uchida, Kosuke Takenaka + Show 5 more

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https://doi.org/10.1038/s41598-019-42959-4

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Abstract

We present evidence for the decomposition and oxidation of amino acids in aqueous solution following irradiation with a nonequilibrium plasma jet. Of 15 amino acids tested in cell culture medium, plasma irradiation induced a marked chemical change in methionine and tryptophan due to the effective production of reactive oxygen species by plasma-water interaction. We also report that plasma-treated methionine and tryptophan aqueous solutions can kill cancer cells, greatly decreasing the viability of human endometrial carcinoma (HEC-1) cancer cells due to the presence of decomposition or oxidation products generated from the amino acid. Plasma-treated methionine and tryptophan aqueous solutions also induced an anti-cancer effect on cancer-initiating cells.

Highlights

We present evidence for the decomposition and oxidation of amino acids in aqueous solution following irradiation with a nonequilibrium plasma jet
We observed a marked decrease in the concentration of (b) methionine and (c) tryptophan, suggesting that sulfur-containing and aromatic amino acids are preferentially destroyed by plasma irradiation, consistent with previous work reported by Takai et al.[33]
In this study we demonstrated that plasma-treated methionine and tryptophan solutions can kill HEC-1 cancer cells efficiently

Summary

Introduction

We present evidence for the decomposition and oxidation of amino acids in aqueous solution following irradiation with a nonequilibrium plasma jet. Of 15 amino acids tested in cell culture medium, plasma irradiation induced a marked chemical change in methionine and tryptophan due to the effective production of reactive oxygen species by plasma-water interaction. We report that plasma-treated methionine and tryptophan aqueous solutions can kill cancer cells, greatly decreasing the viability of human endometrial carcinoma (HEC-1) cancer cells due to the presence of decomposition or oxidation products generated from the amino acid. Atmospheric nonequilibrium plasma jets are of interest for biomedical applications such as wound disinfection and the treatment of cancer tumors[1,2,3,4]. Our measurements showed that some amino acids are oxidized or decompose upon plasma irradiation and that the observed antitumor effect is induced by products generated from these amino acids

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