• Toxicological Research
• /
• v.22 no.1
• /
• pp.39-45
• /
• 2006

As the antioxidant and free radical scavenger, glutathione (GSH) participates in the preservation of cellular redox status and defense against reactive oxygen species and xenobiotics. Glutamate-cysteine ligase (GCL; also known as ${\gamma}$-glutamylcysteine synthetase, EC 6.3.2.2) is the rate limiting enzyme in GSH synthesis. In the present study, the accurate method for determination of GCL activity in crude liver extracts was developed by measuring both ${\gamma}$-glutamylcysteine and GSH from cysteine in the presence of glutamate, glycine and an ATP-generating system. We added glycine to promote the conversion of ${\gamma}$-glutamylcysteine to GSH, and to minimize the possibility of ${\gamma}$-glutamylcysteine metabolism to cysteine and oxoproline by ${\gamma}$-glutamylcyclotransferase. We established optimal conditions and substrate concentrations for the enzyme assay, and verified that inhibition of GCL by GSH did not interfere with this assay. Therefore, this assay of hepatic GCL under optimal conditions could provide a more accurate measurement of this enzyme activity in the crude liver extracts.

• Proceedings of the Korea Environmental Mutagen Society Conference
• /
• 2004.05a
• /
• pp.64-64
• /
• 2004

• Environmental Analysis Health and Toxicology
• /
• v.22 no.1 s.56
• /
• pp.9-17
• /
• 2007

Hermansky-Pudlak Syndrome (HPS) 환자에서 조기에 발생되는 폐섬유화의 원인을 알아보고자, 생쥐 HPS 모델인 ep/ep,pe/pe 돌연변이종의 폐 항산화계의 환성과 방사선에 대한 반응을 측정하였다. HPS 폐에서는 대조군에 비해 glutathione이 더 산화되어 있었고, catalase, glutathione S-transferase(GST) 등의 항산화효소의 활성이 저하되어 있었으며, 10 Gy의 방사선을 조사하였을 때, glutathione 양이 감소하였고, 대조군 폐에서 보여지는 방사선에 의한 ${\gamma}$-glutamylcysteine ligase(GCL), glutathione peroxidase(GPx) 활성의 유의성 있는 증가가 관찰되지 않았다. 이 결과로부터 HPS 환자의 폐는 항산화계 활성이 저하되어 있을 뿐 아니라, 산화적 스트레스가 가해 졌을 때 적응 반응이 매우 취약하여 산화적 환경에 노출된 폐의 병증을 유발할 수 있음을 추측할 수 있다.

• YAKHAK HOEJI
• /
• v.51 no.6
• /
• pp.383-388
• /
• 2007

It has been reported that sulfur-containing intermediates or products in the transsulfuration pathway including S-adenosylmethionine, 5'-methylthioadenosine, glutathione and taurine can prevent liver injury mediated by inflammation response induced by lipopolysaccharide (LPS) treatment. The present study examines the modulation of hepatic metabolism of sulfur amino acid in a model of acute sepsis induced by LPS treatment (5 mg/kg, iv). Serum TNF-alpha and hepatotoxic parameters were significantly increased in rats treated with LPS, indicating that LPS results in sepsis at the doses used in this study. LPS also induced oxidative stress determined by increases in malondialdehyde levels and decreases in total oxy-radical scavenging capacities. Hepatic methionine and glutathione concentrations were decreased, but S-adenosylho-mocysteine, cystathionine, cysteine, hypotaurine and taurine concentrations were increased. Hepatic protein expression of methionine adenosyltransferase, cystathionine beta-synthase and cysteine dioxygenase were induced, but gamma-glutamylcysteine ligase catalytic subunit levels were decreased. The results show that sepsis activates transsulfuration pathway from methionine to cysteine, suggesting an increased requirement for methionine during sepsis.

• Environmental Analysis Health and Toxicology
• /
• v.24 no.4
• /
• pp.303-309
• /
• 2009

Hepatic antioxidant defense systems were examined in rats treated with tetrabromobisphenol-A (TBBPA), a brominated flame retardant, at the doses of 0, 250, 500 and 1,000 mg/kg for four weeks. Hepatic ratio of glutathione disulfide to glutathione (GSH) and levels of malondialdehyde, oxidative stress markers were not changed in rats treated with TBBPA. Hepatic expression of antioxidant enzymes including GSH peroxdiase-1 (GPX-1)/GSH reductase (GR), alpha-, mu- and pi-class glutathione-S-transferase (GST) and gamma-glutamylcysteine ligase catalytic subunit was determined using immunoblot analysis. Alpha-class GSTs, GPX-1 and GR levels were significantly decreased in rats treated with TBBPA at the dose of 500 or 1,000 mg/kg. These results show that TBBPA results in down-regulation of hepatic expression of antioxidant enzymes related with GSH, suggesting the liver in TBBPA-treated rats may be more sensitive to oxidants.

• Preventive Nutrition and Food Science
• /
• v.16 no.4
• /
• pp.313-320
• /
• 2011

The oxidative stress level and antioxidant activities in two green algae (Ulva pertusa and Ulva linza), two brown algae (Agarum cribrosum and Dictyota dichotoma), and three red algae (Grateloupia lanceolata, Carpopeltis affinis, and Gracilaria verrucosa) collected from intertidal regions of Korea were assessed. In the two green algae, although the total glutathione content was not as high as that of the brown algae, the glutathione pool was extremely reduced, and the glutathione reductase (GRd)/glutathione peroxidase (GPx) activity ratio was high, which apparently plays an important role for protection against oxidative damage, as manifested by low lipid peroxidation. In the brown algae, which exhibited a low lipid peroxidation level that was comparable to the green algal species, the highest glutathione content, together with high GPx activity, appears to be the most important factor in their antioxidant protection. The red algal species exhibited extremely high lipid peroxidation levels. They also contained the lowest and most oxidized glutathione among the species, as well as the lowest GRd activity. In spite of the marked difference in the glutathione content, the significant difference in the activity of ${\gamma}$-glutamylcysteine ligase, the rate limiting enzyme for glutathione synthesis, among the species was not exhibited. Our results suggest that there is a significant difference in the levels of oxidative stress and antioxidant capacity among the algal species, and that the glutathione system, especially the efficiency of glutathione recycling, plays a vital role in antioxidative protection in algal species.

• Biomolecules & Therapeutics
• /
• v.26 no.2
• /
• pp.167-174
• /
• 2018

Alterations in sulfur amino acid metabolism are associated with an increased risk of a number of common late-life diseases, which raises the possibility that metabolism of sulfur amino acids may change with age. The present study was conducted to understand the age-related changes in hepatic metabolism of sulfur amino acids in 2-, 6-, 18- and 30-month-old male C57BL/6 mice. For this purpose, metabolite profiling of sulfur amino acids from methionine to taurine or glutathione (GSH) was performed. The levels of sulfur amino acids and their metabolites were not significantly different among 2-, 6- and 18-month-old mice, except for plasma GSH and hepatic homocysteine. Plasma total GSH and hepatic total homocysteine levels were significantly higher in 2-month-old mice than those in the other age groups. In contrast, 30-month-old mice exhibited increased hepatic methionine and cysteine, compared with all other groups, but decreased hepatic S-adenosylmethionine (SAM), S-adenosylhomocysteine and homocysteine, relative to 2-month-old mice. No differences in hepatic reduced GSH, GSH disulfide, or taurine were observed. The hepatic changes in homocysteine and cysteine may be attributed to upregulation of cystathionine ${\beta}-synthase$ and down-regulation of ${\gamma}-glutamylcysteine$ ligase in the aged mice. The elevation of hepatic cysteine levels may be involved in the maintenance of hepatic GSH levels. The opposite changes of methionine and SAM suggest that the regulatory role of SAM in hepatic sulfur amino acid metabolism may be impaired in 30-month-old mice.

• Preventive Nutrition and Food Science
• /
• v.15 no.4
• /
• pp.267-274
• /
• 2010

We assessed the effect of Se-methylselenocysteine (MSC) treatment, at a dose of 0.75 mg/rat/day for 1 or 2 weeks, on the activities of antioxidant systems in Sprague-Dawley rat tissues. Significant changes in glutathione and antioxidant enzyme activities, with different patterns among tissues, were evidenced. Glutathione content and its reduction state in the liver, lung, and kidney were elevated upon MSC treatment, whereas they were significantly lowered in the spleen. Among the tissues exhibiting glutathione increase, there were different enzymatic responses: $\gamma$-glutamylcysteine ligase activity, the rate-limiting enzyme in the glutathione synthesis pathway, was increased in the liver, whereas the activities of the enzymes associated with glutathione recycling, namely, glutathione peroxidase, glutathione reductase, and glucose 6-phosphate dehydrogenase, were significantly increased in the lung and the kidney. The superoxide dismutase activity was decreased in all tissues upon MSC treatment, whereas catalase activity was increased in all tissues but the liver. Lipid peroxidation level was transiently increased at 1 week in the lung and the kidney, whereas it was persistently increased in the spleen. The increase was not evident in the liver. The results indicate that the MSC treatment results in an increase in the antioxidant capacity of the liver, lung, and kidney principally via an increase in glutathione content and reduction, which appeared to be a result of increased synthesis or recycling of glutathione via tissue-dependent adaptive response to oxidative stress triggered by MSC. The spleen appeared to be very sensitive to oxidative stress, and therefore, the adaptive response could not provide protection against oxidative damage.

• The Korea Journal of Herbology
• /
• v.28 no.6
• /
• pp.79-86
• /
• 2013

Objectives : The purpose of this study is to investigate neuroprotective effects and molecular mechanisms of luteolin against ${\beta}$-amyloid ($A{\beta}_{25-35}$)-induced oxidative cell death in BV-2 cells. Methods : The protective effects of luteolin against $A{\beta}_{25-35}$-induced cytotoxicity and apoptotic cell death were determined by MTT dye reduction assay and TUNEL staining, respectively. The apoptotic cell death was further analyzed by measuring mitochondrial transmembrane potential and expression of pro- and/or anti-apoptotic proteins. To elucidate the molecular mechanisms underlying the protective effects of luteolin, intracellular accumulation of reactive oxygen species, oxidative damages, and expression of antioxidant enzymes were examined. Results : Luteolin pretreatment effectively attenuated $A{\beta}_{25-35}$-induced apoptotic cell death indices such as DNA fragmentation, dissipation of mitochondrial transmembrane potential, increased Bax/Bcl-2 ratio, and activation of c-Jun N-terminal kinase and caspase-3 in BV-2 cells. Furthermore, $A{\beta}_{25-35}$-induced intracellular formation of reactive oxygen species and subsequent oxidative damages such as lipid peroxidation and depletion of endogenous antioxidant glutathione were suppressed by luteolin treatment. The neuroprotective effects of luteolin might be mediated by up-regulation of cellular antioxidant defense system via up-regulation of ${\gamma}$-glutamylcysteine ligase, a rate-limiting enzyme in the glutathione biosynthesis and superoxide dismutase, an enzyme involved in dismutation of superoxide anion into oxygen and hydrogen peroxide. Conclusions : These findings suggest that luteolin has a potential to protect against $A{\beta}_{25-35}$-induced neuronal cell death and damages thereby exhibiting therapeutic utilization for the prevention and/or treatment of Alzheimer's disease.