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Abstract

S-Nitrosocompounds are formed when aqueous solutions of cysteine or glutathione are exposed to ultrasound (880 kHz) in air. The yield of the S-nitrosocompounds was as high as 10% for glutathione and 4% for cysteine of the initial thiol concentrations (from 0.1 to 10 mM) in the aqueous solutions. In addition to the formation of S-nitrosocompounds, thiol oxidation to disulfide forms was observed. After the oxidation of over 70% of the sulfhydryl groups, formation of peroxide compounds as well as cysteic acid derivatives was recorded. The formation of the peroxide compounds and peroxide radicals in the ultrasound field reduced the yield of S-nitrosocompounds. S-Nitrosocompounds were not formed when exposing low-molecular-weight thiols to ultrasound in atmospheres of N(2) or CO. In neutral solutions, ultrasound-exposed cysteine or glutathione released NO due to spontaneous degradation of the S-nitrosocompounds. N(2)O(3), produced due to the spontaneous degradation of the S-nitrosocompounds in air, nitrosylated sulfhydryl groups of glutathione manifested in the appearance of new absorption bands at 330 and 540 nm. The nitrogen compounds formed in an ultrasound field modified the sulfhydryl groups of apohemoglobin and serum albumin. The main target for ultrasound-generated oxygen free radicals were cystine residues oxidized to cysteic acid residues.

HPLC analysis of human erythrocytic glutathione forms using OPA and N-acetyl-cysteine ethyl ester: Evidence for nitrite-induced GSH oxidation to GSSG

“…Also, it has been reported that methemoglobin is reduced back to hemoglobin, with GSH being oxidized to GSSG [26]. Formation of mixed disulfides of GSH with proteins including hemoglobin (HbSSG) has been observed by other investigators [33,37,38].…”

“…It is worth mentioning that nitrite may react with deoxyhemoglobin to form methemoglobin and nitrosyl hemoglobin. It is well known that GSH in RBC may prevent hemoglobin from oxidation [25,26]. We have hypothesized that GSH may be required for the reduction of methemoglobin formed during oxyhemoglobin-catalysed nitrite oxidation in RBC.…”

Fluorescent properties of thiochrome in solvents of different polarity

“…Thiamine is also oxidized to TChr by hydroxyl [9] or peroxyl radicals and in reactions with peroxidases [10].…”

Prevention of incipient diabetic cardiomyopathy by high-dose thiamine

“…Thia--nize due to lack of typical clinical features, is speculated to be bring out by (1) an increased thiamine renal clearance (Thornalley et al, 2007), (2) a decreased intestinal absorption and membrane transport of thiamine (Patrini et al, 1996), and (3) an increased consumption of thiamine caused by an augmented glucose metabolism (Yui et al, 1980;Seligmann et al, 1991). Additionally, high production of reactive oxygen species (ROS) in diabetes mellitus could oxidize thiamine, with the production of inactive compounds, such as thiochrome and oxydihydrothiochrome (Stepuro et al, 1997;Obrenovich and Monnier, 2003).…”