• Applied Biological Chemistry
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• v.48 no.1
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• pp.53-59
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• 2005

The effect of various stressors such as reductant ascorbic acid, signalling molecules (salicylic acid and methyl jasmonic acid), heavy metals $(NiCl_2,\;and\;MnSO_4)$ and NaCl on the glutathione peroxidase (GPX) activities and isoenzyme expression patterns were investigated in rice seedling roots. Total GPX activity increased according to the increase of ascorbic acid concentration. Prominent enhancement of GPX1 isozyme due to ascorbic acid contributed to the increase of total GPX activity. GPX showed different reactivity toward salicylic acid and methyl jasmonic acid. GPX activity increased at 0.1 mM salicylic acid, and then decreased thereafter. However, GPX increased gradually in a methyl jasmonic acid concentration-dependent manner, and 3 fold increase of GPX activity was found at 1 mM methyl jasmonic acid. Moreover, GPX1 isozyme increased according to the increase of salicylic acid, while GPX1 isozyme decreased according to the increase of methyl jasmonic acid. When metal ions were treated, GPX activity increased considerably according to the increase of $NiCl_2$ concentration, however, GPX activity increased about 2 fold at 0.5 mM $CuSO_4$ and then decreased. Enhancement of GPX1 isozyme contributed to the increase of total GPX activities in $NiCl_2-treated$ and $MnSO_4-treated$ rice seedlings. Total GPX activity increased 1.7 fold in response to 300 mM NaCl. Especially GPX2 isozyme showed gradual increase according to the increase of NaCl concentration.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1041-1046
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• 2006

Selenium-containing peptide (selenium peptide) was produced by autolysis of total proteins of Saccharomyces cerevisiae grown with inorganic selenium. Selenium peptide exhibited antioxidant activity as a glutathione peroxidase (GPx) mimic, and its activity was dependent on the hydrolysis methods. The GPx-like activity of the hydrolyzed selenium peptide increased 2.7-folds when digested by protease, but decreased by acid hydrolysis. During the autolysis of the yeast cell, the GPx-like activity and selenium content increased 4.3- and 2.3-folds, respectively, whereas the average molecular weight (MW) of selenium peptide decreased 70%. The GPx-like activity was dependent on the MW of selenium peptide and was the highest (220 U/mg protein) at 9,500 dalton. The maximum GPx-like activity (28,600 U/g cell) was obtained by 48 h of autolysis of the cells, which were precultured with 20 ppm of selenate. Selenium peptide showed little toxicity, compared with highly toxic inorganic selenium. These results show the potential of selenium peptide as a nontoxic antioxidant that can be produced by simple autolysis of yeast cells.

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.36-39
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• 2003

Many defined cell culture media were formulated over 3() years ago and may be deficient in certain micronutrients whose essentiality has only subsequently been recognised. The objective of this study was to evaluate whether alpha-minimal essential medium (MEM) supplemented with 10% foetal bovine serum contained sufficient selenium for optimal activity of the selenium containing enzymes cytosolic glutathione peroxidase (cGPx) and phospholipid hydroperoxide glutathione peroxidase (PHGPx) in cultured Chinese hamster ovary (CHO) cells. Additionally, the effect of zinc deficiency and metallothionein (MT) overexpression on cGPx and PHGPx activity was studied. The addition of 100 nM of selenous acid to the culture medium increased cGPx expression by 10-fold and PHGPx by about 2-fold in both wild-type CHO-K1 cells and CHO-K1 cells overexpressing mouse MT-1. Zinc deficiency had no significant effect on enzyme activity, but cells overexpressing mouse MT-1 had higher levels of cGPx activity. Zinc deficiency decreased cell survival but overexpression of MT-1 was partially protective, probably because its presence in quantity favoured the uptake, sequestration and cellular retention of any remaining zinc. This study demonstrates that selenium in complete alpha-MEM is insufficient for optimal cGPx and PHGPx activity and may compromise the cellular response to oxidative stress.

• BMB Reports
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• v.43 no.3
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• pp.170-175
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• 2010

Chaperone;Glutathione peroxidase;Peroxiredoxin;Schizosaccharomyces pombe;Thioredoxin peroxidase;To investigate the differences in the functional roles of peroxiredoxins (Prxs) and glutathione peroxidase (GPx) of Schizosaccharomyces pombe, we examined the peroxidase and molecular chaperone properties of the recombinant proteins. TPx (thioredoxin peroxidase) exhibited a capacity for peroxide reduction with the thioredoxin system. GPx also showed thioreoxin-dependent peroxidase activity rather than GPx activity. The peroxidase activity of BCP (bacterioferritin comigratory protein) was similar to that of TPx. However, peroxidase activity was not observed for PMP20 (peroxisomal membrane protein 20). TPx, PMP20, and GPx inhibited thermal aggregation of citrate synthase at 43$^{\circ}C$, but BCP failed to inhibit the aggregation. The chaperone activities of PMP20 and GPx were weaker than that of TPx. The peroxidase and chaperone properties of TPx, BCP, and GPx of the fission yeast are similar to those of Saccharomyces cerevisiae. The fission yeast PMP20 without thioredoxin-dependent peroxidase activity may act as a molecular chaperone.

• Journal of Ginseng Research
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• v.47 no.4
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• pp.561-571
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• 2023

Background: Escalating evidence shows that ginseng possesses an antiaging potential with cognitive enhancing activity. As mountain cultivated ginseng (MCG) is cultivated without agricultural chemicals, MCG has emerged as a popular herb medicine. However, little is known about the MCG-mediated pharmacological mechanism on brain aging. Methods: As we demonstrated that glutathione peroxidase (GPx) is important for enhancing memory function in the animal model of aging, we investigated the role of MCG as a GPx inducer using GPx-1 (a major type of GPx) knockout (KO) mice. We assessed whether MCG modulates redox and cholinergic parameters, and memory function in aged GPx-1 knockout KOmice. Results: Redox burden of aged GPx-1 KO mice was more evident than that of aged wild-type (WT) mice. Alteration of Nrf2 DNA binding activity appeared to be more evident than that of NFκB DNA binding activity in aged GPx-1 KO mice. Alteration in choline acetyltransferase (ChAT) activity was more evident than that in acetylcholine esterase activity. MCG significantly attenuated reductions in Nrf2 system and ChAT level. MCG significantly enhanced the co-localization of Nrf2-immunoreactivity and ChAT-immunoreactivity in the same cell population. Nrf2 inhibitor brusatol significantly counteracted MCG-mediated up-regulation in ChAT level and ChAT inhibition (by k252a) significantly reduced ERK phosphorylation by MCG, suggesting that MCG might require signal cascade of Nrf2/ChAT/ERK to enhance cognition. Conclusion: GPx-1 depletion might be a prerequisite for cognitive impairment in aged animals. MCG-mediated cognition enhancement might be associated with the activations of Nrf2, ChAT, and ERK signaling cascade.

• Journal of Life Science
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• v.19 no.2
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• pp.228-233
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• 2009

The purpose of this study is to evaluate the activities of five different antioxidant enzymes in various tissues of Papilio xuthus during pupal stage. Superoxide dismutase (SOD) activity in haemolymph was the highest just after pupation and then decreased gradually until 7 days after pupation but the activity in other tissue was constant during metamorphosis. This result indicates that primary antioxidant process of reactive oxygen species proceed in haemolymph. Catalase (CAT) activity in studied tissues was also the highest just after pupation and its relative activity was also high during pupal stage, suggesting that CAT is the primary enzyme in catalysis of hydrogen peroxide. Glutathion peroxidase (GPX) activity was constant and its relative activity was very low in all tested tissues. Glutathione S-transferase (GST) activity in haemolymph was high at 3 days and 5 days after pupation, and the activity in fat body was the highest at the 1 day after pupation and then decreased gradually for 7 days after pupation. Glutathion reductase (GR) activity in haemolymph and fat body was high at 1 day after pupation, but relatively low GR activity was detected in the rest tissues. Based on these results, GST activity was higher than that of GPX and GR, and it is also believed that GST was more involved in reduction process through lipid peroxidation than GPX.

• YAKHAK HOEJI
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• v.48 no.4
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• pp.219-225
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• 2004

The present investigation was undertaken to examine the anticancer activity of the methanol extract from Houttuynia cordata on ICR mouse with induced abdominal cancer and L1210 cancer cells. When the methanol extract of Houttuynia cordata (10∼200 $\mu\textrm{g}$/$m\ell$) was administered orally to ICR mouse with abdominal cancer, 47.8% of the best life prolonging effect was obtained. In case of cytotoxicity study (inhibition of cell proliferation) of Houttuynia cordata extract against L1210 cells, $IC_{50}$/ was found to be 62.8 $\mu\textrm{g}$/$m\ell$. In contrast to such considerable toxicity against cancer cell line, the toxicity demonstrated by the identical extract against normal lymphocytes was very meagre as shown to be < 5% compared with 86.5% in case of L1210 cells at the same condition. To get an insight into the reaction mechanism undelying the anticancer activity, $O_2$ion quantity and antioxidant enzyme activities such as superoxide dismiutase (SOD) and glutathione peroxidase (GPx) of L1210 cells in the presence of Houttuynia cordata extract were measured. The increased values of SOD and GPx enzyme activities in addition to the augmented generation of $O_2$ ion in L1210 cells implied that the reactive oxygen species induding $O_2$ion which were presumably induced by Houttuynia cordata extract might have participated in the process of L1210 cells cytotoxicity.

• Journal of Plant Biotechnology
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• v.36 no.2
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• pp.149-156
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• 2009

Application of exogenous polyamines (PAs) reduced the paraquat (PQ)-induced cotyledon injuries in radish seedling plants with 1 mM spermidine (Spd) being the most effective protectant. PQ injury symptoms in the cotyledons, e.g., large accumulation of $H_2O_2$, and losses of fresh weight, chlorophyll, and proteins, were significantly alleviated. Likewise, analysis of $H_2O_2$-scavenging enzymes such as catalase (CAT) and guaiacol peroxidase (GPX) showed that pretreatment with Spd among PAs remarkably increased total CAT activity and strongly retarded PQ-induced rapid decline in total GPX activity. In a native gel assay, one CAT isozyme (CAT1) and two GPX isozymes (GPX1 and a newly synthesized GPX isozyme) proved to be more responsible for PQ tolerance, as manifested by the strong increases in their activities by Spd pretreatment. Based on these results, we can suggest that PAs (especially 1 mM Spd) may function as antioxidant protectors by invoking CAT and GPX enzymes which control the endogenous $H_2O_2$ level in radish cotyledons exposed to PQ.

• Molecules and Cells
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• v.39 no.8
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• pp.631-638
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• 2016

Glutathione peroxidase 3 (GPx3), an antioxidant enzyme, acts as a modulator of redox signaling, has immunomodulatory function, and catalyzes the detoxification of reactive oxygen species (ROS). GPx3 has been identified as a tumor suppressor in many cancers. Although hyper-methylation of the GPx3 promoter has been shown to down-regulate its expression, other mechanisms by which GPx3 expression is regulated have not been reported. The aim of this study was to further elucidate the mechanisms of GPx3 regulation. GPx3 gene analysis predicted the presence of ten glucocorticoid response elements (GREs) on the GPx3 gene. This result prompted us to investigate whether GPx3 expression is regulated by the glucocorticoid receptor (GR), which is implicated in tumor response to chemotherapy. The corticosteroid dexamethasone (Dex) was used to examine the possible relationship between GR and GPx3 expression. Dex significantly induced GPx3 expression in H1299, H1650, and H1975 cell lines, which exhibit low levels of GPx3 expression under normal conditions. The results of EMSA and ChIP-PCR suggest that GR binds directly to GRE 6 and 7, both of which are located near the GPx3 promoter. Assessment of GPx3 transcription efficiency using a luciferase reporter system showed that blocking formation of the GR-GRE complexes reduced luciferase activity by 7-8-fold. Suppression of GR expression by siRNA transfection also induced down-regulation of GPx3. These data indicate that GPx3 expression can be regulated independently via epigenetic or GR-mediated mechanisms in lung cancer cells, and suggest that GPx3 could potentiate glucocorticoid (GC)-mediated anti-infla-mmatory signaling in lung cancer cells.

• YAKHAK HOEJI
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• v.48 no.1
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• pp.93-98
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• 2004

The purpose of this study was to evaluate the effect of pharbitidis seed extract (PE) on antioxidant enzymes. The cytotoxicities of PE were measured by 3- (4,5-dimethlthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; The change of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activity assay were measured. The SOD activities by PE-treated groups were lower than control group's one. In the co-treated with hydrogen peroxide ($H_2O$$_2$) group, SOD activity was higher than $H_2O$$_2$ treated group's activity In the case of GPx, GPx activities were increased in both PE-treated and co-treated with $H_2O$$_2$ group. In the case of CAT $H_2O$$_2$ treated group's activityies were very increased. The CAT activities by PE-treated groups were lower than control group's one, but the activity of co-treated group with H $_2$O$_2$ was higher than that of control group's one. These results suggest that PE has antioxidant activity.