OXIDATION OF GLUTATHIONE AND CYSTEINE BY FREE-RADICALS ARISING UNDER THE ACTION OF ULTRASOUND

In aqueous solutions and air atmosphere, cysteine and glutathione are oxidized by free radicals arising under the action of ultrasound first to cystine and glutathione disulfide to form. Small amounts of S-nitr osocysteine and S-nitrosoglutathione. When acted upon simultaneously b y hydroxyl free radicals and H2O2, glutathione disulfide and cystine a re oxidized, respectively, to glutathionecysteic and cysteic acid to f orm. Some amounts of taurine and sulfopropionic acid. On exposure of c ysteine to ultrasound in a nitrogen atmosphere, alanine and serine are formed in addition to the above mentioned products, with the yield of oxidation products being decreased. In the presence of organic compou nds, the rate of oxidation of glutathione or cysteine to the disulfide forms is slowed down. Aliphatic alcohols, aldehydes, urea, and dimeth ylsulfoxide completely protect cysteine and glutathione disulfide from further transformations. The role of volatile compounds (traps of oxy gen free radicals and nitrogen oxides) in non-enzymatic conversions an d catabolism of glutathione and cysteine is discussed.