BIOLOGY
Year : 2010  |  Volume : 1  |  Issue : 1  |  Page : 16-21 Table of Contents     

Intracellular scavenging activity of Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) in the fission yeast, Schizosaccharomyces pombe


1 Department of Biochemistry, Upper Nile University, P.O. Box 1660 Khartoum, Sudan
2 Department of Molecular Biology and Genetics, Istanbul University, Vezneciler 34118, Istanbul, Turkey

Date of Web Publication23-Oct-2010

Correspondence Address:
Ismail Hamad
Department of Biochemistry, Upper Nile University, Faculty of Medicine and Health Sciences, P.O. Box 1660 Khartoum
Sudan
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-9668.71667

Rights and Permissions
   Abstract 

The ability of Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid), a water-soluble vitamin E analogue, to prevent oxidative damages is well characterized, but the mechanisms underlying it remain unclear. The protective effect of Trolox pre-treatment on H 2 O 2 -induced toxicity might be attributed to the decreased cellular permeability to H 2 O 2 or in vitro scavenging activity of Trolox, induction of antioxidant enzymes or the direct scavenging activity of Trolox. The results obtained rule out the first and second possibilities and intracellular scavenging activity was found to be the mechanism whereby Trolox confers protection. This was confirmed by measuring protein oxidation (levels), and the observed decrease in proteasomal activity indicated that the decrease in protein carbonyls was due to Trolox scavenging activity rather than proteasome activation. In conclusion, the intracellular scavenging activity of Trolox is a key protective mechanism against H 2 O 2 . These findings obtained in Schizosaccharomyces pombe, a good model organism for eukaryotic cells, can be used as standard protocols for investigating the antioxidant activity of pure or complex potential antioxidants.

Keywords: Fission yeast, hydrogen peroxide, oxidative stress, protein oxidation, Schizosaccharomyces pombe, Trolox


How to cite this article:
Hamad I, Arda N, Pekmez M, Karaer S, Temizkan G. Intracellular scavenging activity of Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) in the fission yeast, Schizosaccharomyces pombe. J Nat Sc Biol Med 2010;1:16-21

How to cite this URL:
Hamad I, Arda N, Pekmez M, Karaer S, Temizkan G. Intracellular scavenging activity of Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) in the fission yeast, Schizosaccharomyces pombe. J Nat Sc Biol Med [serial online] 2010 [cited 2020 Jan 25];1:16-21. Available from: http://www.jnsbm.org/text.asp?2010/1/1/16/71667


   Introduction Top


Reactive oxygen species (ROS) are produced as normal by-products of cellular metabolism. These species are also derived from external environmental factors such as redox active drugs, radiation and heavy metals. The major source of ROS is the mitochondrial respiratory chain, which accounts for 85-90% of the oxygen consumed by the cells. [1] ROS can cause damage to proteins, lipids and nucleic acids and thereby compromise cell viability. Under normal physiological conditions, cellular damages are prevented by antioxidant defenses that neutralize the ROS. [2] These include ROS-scavenging molecules (e.g., superoxide dismutase, catalase), oxidative damage-repair enzymes (e.g., methionine sulfoxide reductase) and mechanisms such as the S-thiolation of oxidation-susceptible proteins, which prevents oxidation by forming reversible mixed-disulfide bonds with glutathione/thiol. [3] However, under specific stress conditions, the levels of ROS exceed the antioxidant capacity of the cells and the cells face an oxidative stress. This unbalanced situation can result from: (i) a decrease in antioxidants, due to depletion of such defenses (e.g., by xenobiotics that are metabolized by conjugation to glutathione or due to mutations that affect antioxidant defenses), (ii) an increased production of ROS (e.g., by exposure to hyperoxia, compounds that generate ROS or due to excessive activation of systems that produce ROS) or (iii) both. [4]

Such "oxidative stress" is associated with several human pathologies, including cancer, cardiovascular diseases, Down's syndrome, Friedreich's ataxia, rheumatoid arthritis, autoimmune diseases and acquired immunodeficiency syndrome. Oxidative damage is also emerging as an important factor in mutagenesis, tumorigenesis, ageing and age-related disorders such as Parkinson's and Alzheimer's diseases. [5]

Protein oxidation is defined as the covalent modification of protein induction, either directly by ROS or indirectly by a reaction with secondary by-products of oxidative stress. Oxidative damages to proteins can lead to diverse functional consequences, such as inhibition of enzymatic and binding activities, protein aggregation and enhanced susceptibility to proteolysis. [6] Protein oxidation serves as a useful marker for assessing oxidative stress. The most commonly used marker of protein oxidation is the protein carbonyls. The use of protein carbonyl groups as biomarkers of oxidative stress has some advantages in comparison with the measurement of other oxidation products because of the relative early formation and the relative stability of carbonylated proteins. Most of the assays for detection of protein carbonyl groups involve derivatization of the carbonyl group with 2,4-dinitrophenylhydrazine (DNPH), which leads to the formation of a stable dinitrophenyl (DNP) hydrazone product. This then can be detected by various means, such as spectrophotometric assay, enzyme-linked immunosorbent assay (ELISA) and one- or two-dimensional electrophoresis followed by Western blot immunoassay. [7]

Proteasomes are large protein complexes inside all eukaryotes and archaea as well as some bacteria. In eukaryotes, they are located in the nucleus and in the cytoplasm. The proteasome is present in two major forms, the 20S and the 26S proteasomes. The former is a multimeric proteolytic enzyme in a cylinder-like shape, whereas the latter is a complex consisting of two 19S regulatory complexes and one 20S proteasome unit. The 26S proteasome degrades various kinds of excess proteins that have been ubiquitinated with the expense of ATP. This proteasome plays essential roles in the regulation of the cell cycle by specific ubiquitin-mediated proteolysis. [8]

Besides targeted degradation of regulatory proteins, an important function of the proteasome is the degradation of oxidized and aberrant proteins. [9] Increased accumulation of highly oxidized and cross-linked protein aggregates within the cell observed during aging has been attributed to decreased proteasome function. [10]

Natural antioxidants like vitamin C and E, carotenoids and polyphenols are claimed to protect against cancer and cardiovascular diseases, and there is an increasing interest in the use of natural and synthetic antioxidants as functional food ingredients or as food supplements. However, on the other hand, at high doses, toxic pro-oxidant action may become important. [11]

Vitamin E is the name for a group of biologically active substances including tocopherols and tocotrienols. [1] a-tocopherol shows the highest biological activity and is the most common form found in the human body. Tocopherols inhibit lipid peroxidation by scavenging lipid peroxyl radicals much faster than these radicals can react with adjacent fatty acid side chains or membrane proteins. In addition, both tocopherols and tocotrienols quench and react with singlet oxygen and slowly react with superoxide anions. [12]

Trolox (6-hydroxy- 2, 5, 7, 8-tetramethylchromane-2-carboxylic acid) is a water-soluble analogue of the free radical scavenger α-tocopherol. Trolox has advantages over α-tocopherol, which is lipid soluble because it can be incorporated in both the water and the lipid compartments of cells. Satoh et al. have claimed that the antioxidant property of Trolox surpasses that of α-tocopherol.[13] Many studies investigated the protective effect of Trolox, [14],[15],[16] but the mechanisms underlying these effects remain unclear.

The fission yeast, Schizosaccharomyces pombe, is well known for its contribution to the understanding of molecular mechanisms of cell cycle in eukaryotes. It is probably closer to higher eukaryotes than Saccharomyces cerevisiae, and represents a good model organism for mammalians.[17] Here, it was used as a model system to evaluate the mechanism of Trolox-mediated protective effects against ROS.

We showed that Trolox was able to prevent or reduce some of the H 2 O 2 -induced toxic effects in S. pombe. In conclusion, the intracellular scavenging activity of Trolox was found to be the key protective mechanism against H 2 O 2 .

These findings obtained in S. pombe can be used as standard protocols for investigating the antioxidant activity of pure or complex potential antioxidants.


   Materials and Methods Top


Organisms and growth conditions

The strain used in this work was wild type S. pombe (972h - ). Yeast cells were grown in YE medium (0.5% yeast extract, 3% glucose) at 30 o C on a rotary shaker at 180 rpm under aerobic conditions. Yeast cells were pre-treated with 1 mM Trolox for 2 (short-term) and 14 h (long-term) in YE medium. Later, they were collected by centrifugation at 1,200 g, washed with sterile distilled water and re-suspended in YE medium. Exponentially growing cells at 1 × 10 7 cells/ml were treated with 1 mM hydrogen peroxide for 30 min.

Viability determinations

To calculate cell viability, appropriate dilutions of the cultures were spread on plates with solid YEA medium (0.5% yeast extract, 3% glucose, 2% agar). These plates were incubated at 30 o C and the colony forming units were counted at the end of the third day.

Estimation of hydrogen peroxide in culture media

The H 2 0 2 assay was adapted from the methods of Pick and Keisari. [18] Immediately prior to the assay, phenol red and horseradish peroxidase were added to 1 ml of assay buffer (10 mM potassium phosphate, pH 7 and 40 mM NaCl) at a final concentration of 0.1 mg/ml and 8.5 U/ml, respectively. A 500 μl aliquot of the culture media was then added and the solution was mixed and incubated at 25°C for 5 min. After the reaction was stopped by adding 10 μl of 1 N NaOH, optical density was measured at 610 nm using a Biotek μQuant Microplate Spectrophotometer (Winooski, VT, USA). H 2 0 2 concentrations were calculated from a standard curve evaluated for each assay from dilutions of 30% H 2 0 2 .

Measurement of ROS generation

Intracellular oxidation level was measured as described previously. [19] After pre-incubation of the yeast cells (10 7 cells/ml) in YE medium with 40 μM DCFH-DA at 30 o C for 60 min, the cells were treated with 1 mM H 2 O 2 for 30 min and then washed and re-suspended in 100 μl phosphate-buffered saline (PBS). Fluorescent intensity of the cell suspension was measured using a Bio-Tek FL800 fluorescence microplate reader (Winooski, VT, USA). with excitation at 480 nm and emission at 530 nm. The relative fluorescent intensity was expressed as arbitrary units/10 7 cells.

Preparation of crude cell-free extract

Cells were collected by centrifugation and re-suspended in 200 μl lysis buffer (50 mM Tris, pH 7.5, 150 mM NaCl, 5 mM EDTA, 10% glycerol, 1 mM PMSF, 1 mM DTT). Cells were disrupted by vortexing with acid-washed glass beads (diameter 425-600 mm) for 10 min at 60 s intervals, interspersed with periods of cooling in an ice bath. Cellular debris was removed by centrifugation at 15,000 g at 4 o C for 20 min. [20] The supernatant was collected and the protein concentration was determined according to Waterborg (2002) using bovine serum albumin as a standard. [21]

Catalase assay

Catalase activity was determined spectrophotometrically by monitoring the disappearance of H 2 O 2 at 240 nm as described previously. [22] The mixture containing 680 μl of 50 mM potassium phosphate buffer (pH 7.2) and 480 μl of 40 mM H 2 O 2 was incubated at 30°C for 2.5 min. Enzymatic reaction was initiated by adding 40 μl of the cell extract. The decrease in absorbance at 240 nm was monitored. Catalase activity was expressed as ∆A 240 /min/mg protein.

Immuno-detection of protein carbonyls

As a result of protein oxidation, carbonyl groups are introduced into protein side chains by a site-specific mechanism. We used an OxyBlot kit (Millipore, Billerica, MA, USA) to immunodetect these carbonyl groups in oxidatively modified proteins as described by the manufacturer. Briefly, DNPH derivatization was carried out for 15 min on 15 μg of protein. Five micrograms of protein was separated on 10% SDS polyacrylamide gels, transferred to nitrocellulose membrane and stained by Red Ponceau to check for equal transfer. The membrane was probed with first antibody, specific to the DNP moiety of the proteins. The next step was incubation with horseradish peroxidase-antibody conjugate directed against the primary antibody. Immunoblots were visualized using the ECL-Plus Western Blotting Detection system supplied by (GE healthcare, Piscataway, NJ, USA), with exposure times between 30 s and 2 min. A second gel containing duplicate samples was run and stained with the silver staining technique. [23]

Measurement of 20S proteasome activity

Quantitative in vitro analysis of 20S proteasome activity was performed by measuring the hydrolysis of the fluorogenic peptidyl substrate Suc-Leu-Leu-Val-Tyr-AMC. [24] Cells were disrupted by vortexing with acid-washed glass beads into buffer containing 0.25 M sucrose, 25 mM HEPES, pH 7.8, 10 mM MgCl 2 , 1 mM EDTA and 1 mM DTT. Lysates were centrifuged at 14,000 g for 30 min at 4°C. Cell lysates were diluted with proteolysis buffer (50 mM Tris, pH 7.8, 5 mM magnesium acetate, 20 mM KCl, 0.5 mM DTT) to a protein concentration of 50 μg/ml. The peptidase activity was measured by the addition of 90 μl of proteolysis buffer and 10 μl of Suc-Leu-Leu-Val-Tyr-AMC (4 mM stock solution in DMSO) to 100 μl of the diluted cell lysate. The mixture was incubated at 37°C for 1 h. The reaction was stopped by addition of an equal volume of ice-cold ethanol and 1.6 ml of 0.125 M sodium borate (pH 9.0). The fluorescence determination was performed at 380 nm excitation and 440 nm emission using free AMC as a standard. Results were presented as nM AMC/mg protein/min.

Statistical analysis

All data were represented as mean ±SD. The statistical significance of the difference between the control and the treated sample was assessed by one-way ANOVA and Dunnett's multiple comparison test. Results were considered statistically significant at P < 0.05.


   Results and Discussion Top


The objective of the current study was to evaluate the mechanism of Trolox-mediated protective effect against H 2 O 2 -induced oxidative damages in the fission yeast S. pombe.

Determination of sub-lethal hydrogen peroxide and non-toxic trolox concentration

To assess the consequences of H 2 O 2 -induced oxidative stress and the protective effect of Trolox in S. pombe, we first determined the sub-lethal concentration of H 2 O 2 and non-toxic dose of Trolox. Cells were treated with H 2 O 2 in the concentration range of 0.2-5 mM. The sub-lethal H 2 O 2 concentration was found to be 1 mM, which resulted in 29% increased cell mortality following 30 min of incubation. To establish the maximum non-toxic concentration of Trolox, cells were treated with 0.005-1 mM Trolox. 1 mM Trolox was used throughout the experiments as it increased cell survival significantly (data not shown).

The impact of 1 mM H 2 O 2 and 1 mM Trolox on cell growth in the mid-exponential growth phase was additionally tested. As indicated in [Table 1], pre-treatment of S. pombe cells with 1 mM Trolox for 14 h followed by exposure to 1 mM H 2 O 2 for 30 min showed the strongest protective effect compared with cells treated with H 2 O 2 alone.
Table 1: Effects of Trolox pre-treatment on the viability, H2O2 uptake, generation of ROS, catalase activity and proteasome activity in the fi ssion yeast, S. pombe


Click here to view


Our results with Trolox are in agreement with those obtained by Raspor et al.,[15] demonstrating that Trolox treatment increased cell viability, decreased intracellular ROS formation and suppressed DNA oxidation in Saccharomyces cerevisiae. Additionally, it has been reported that vitamin E in the concentration range of 50 μM to 100 mM did not have any genotoxic effect on the yeast cells. [25]

Once the non-genotoxic potential of Trolox was confirmed, its protective effect on H 2 O 2 -induced toxicity was further investigated.

Effect of trolox on H 2 O 2 uptake, ROS generation and catalase activity

The protective effect of Trolox pre-treatment on H 2 O 2 -induced toxicity might be attributed to (i) change in cellular uptake of H 2 O 2 or in vitro scavenging activity, (ii) induction of antioxidant enzymes (glutathione peroxidase, catalase) or (iii) direct scavenging activity of Trolox. For these reasons, extracellular H 2 O 2 concentration, intracellular oxidation level and catalase activity were determined.

H 2 O 2 level in the medium revealed that protection against H 2 O 2 could not be attributed to reduced H 2 O 2 uptake and/or to the in vitro scavenging activity of Trolox, because no significant difference between the H 2 O 2 concentrations of Trolox pre-treated and of non-treated cultures were observed [Table 1].

We analyzed whether the Trolox-protective effect was due to scavenging of intracellular ROS in S. pombe using a fluorescent dye, DCFH-DA [Table 1]. Trolox pre-treatment suppressed ROS generation and a significant decrease in peroxide production was detected when the cells were treated with Trolox for 14 h. These results were consistent with the findings of Peus et al, on human keratinocytes, in which Trolox was found to decrease the intracellular H 2 O 2 generation in a dose-dependent manner. [26]

A significant increase in catalase activity was detected in cells pre-treated with Trolox for 2 h but not in the cells pre-treated for 14 h [Table 1]. Susa et al, also found that a 20 h pre-treatment with 0.5 mM vitamin E did not affect the activities of antioxidant enzymes, including superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione level in rat hepatocytes. [27] According to Raspor et al, after prolonged exposure, such enzymatic activities tend to go to normal level. [15]

It was concluded that the low level of H 2 O 2 is due to Trolox-mediated increased intracellular scavenging ability rather than alteration in H 2 O 2 transport, in vitro scavenging activity or induction of antioxidant defense system.

Effect of trolox on protein oxidative modification and proteasome activity

If Trolox decreases the level of intracellular ROS, it would be expected to decrease damage to biomolecules. We used protein carbonyls as a marker for protein oxidation. Protein carbonyls are generated by a variety of mechanisms [7] and are sensitive indices of oxidative injury. The results obtained from protein carbonyl assays [Figure 1] indicated that pre-treatment of the S. pombe cells with Trolox for 2 and 14 h decreased the oxidative damage to proteins induced by 1 mM H 2 O 2 for 30 min.
Figure 1: Pat tern of oxidatively damaged proteins of Schizosaccharomyces pombe pre-treated with Trolox and stressed with H2O2. Samples were prepared as described under Materials and Methods. The protein stain was shown in (a). Major oxidatively damaged proteins were indicated in (b). C1: untreated control, C2: cells pre-treated with Trolox for 2 h, C3: cells pre-treated with Trolox for 14 h. T1: cells treated with H2O2 alone, T2: cells pre-treated with Trolox for 2 h and then exposed to H2O2, T3: cells pre-treated with Trolox for 14 h and then exposed to H2O2.

Click here to view


It has been amply documented that the 20S proteasome degrades oxidatively damaged proteins. [28],[29] The protective effect of Trolox against H 2 O 2 -induced protein damage was further confirmed by measuring the 20S proteasome activity. The results obtained here indicated that the protective effect of Trolox pre-treatment on protein carbonyls was due to the increased intracellular scavenging ability rather than Trolox-mediated activation of the proteasome [Table 1].

This study provides proof that intracellular scavenging activity is the mechanism by which Trolox treatment provides prevention against oxidative damages induced by H 2 O 2 in the fission yeast, which represents a good model for mammalian cells. The methods presented can be used as standard protocols for investigating the antioxidant activity of pure or complex potential antioxidants.

 
   References Top

1.Halliwell B, Gutteridge CM. Free radicals in biology and medicine. 3 rd rev. ed. London: Oxford University Press; 2004. p. 936.  Back to cited text no. 1      
2.Cadenas E. Biochemistry of oxygen toxicity. Annu Rev Biochem 1989;58:79-110.  Back to cited text no. 2  [PUBMED]    
3.Weissbach H, Resnick L, Brot N. Methionine sulfoxide reductases: History and cellular role in protecting against oxidative damage. Biochim Biophys Acta 2005;1703:203-12.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]  
4.Costa V, Moradas-Ferreira P. Oxidative stress and signal transduction in Saccharomyces cerevisiae: Insights into ageing, apoptosis and diseases. Mol Aspects Med 2001;22:217-46.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]  
5.Halliwell B. Antioxidants and human disease: A general introduction. Nutr Rev 1997;55:S44-9.  Back to cited text no. 5  [PUBMED]    
6.Shacter E. Quantification and significance of protein oxidation in biological samples. Drug Metab Rev 2000;32:307-26.  Back to cited text no. 6  [PUBMED]  [FULLTEXT]  
7.Dalle-Donne I, Rossi R, Giustarini, D, Milzani, A, Colombo R. Protein carbonyl groups as biomarkers of oxidative stress. Clin Chim Acta 2003;329:23-38.  Back to cited text no. 7      
8.Davies KJ. Degradation of oxidized proteins by the 20S proteasome. Biochimie 2001;83:301-10.  Back to cited text no. 8  [PUBMED]  [FULLTEXT]  
9.Grune T, Davies KJ. The proteasomal system and HNE-modified proteins. Mol Aspects Med 2003;24:195-204.  Back to cited text no. 9  [PUBMED]  [FULLTEXT]  
10.Stadtman ER. Protein oxidation in aging and age-related diseases. Ann N Y Acad Sci 2001;928:22-38.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]  
11.Rietjens IM, Boersma MG, de Haan L, Spenkelink B, Awad HM, Cnubben NH, et al. The pro-oxidant chemistry of the natural antioxidants vitamin C, vitamin E, carotenoids and flavonoids. Environ Toxicol Pharmacol 2002;11: 321-33.  Back to cited text no. 11      
12.Birgelius-Flohe R, Traber MG. Vitamin E: Function and metabolism. FASEB J 1999;13:1145-55.  Back to cited text no. 12      
13.Satoh K, Kadofuku T, Sakagami H. Effect of Trolox, a synthetic analog of alpha-tocopherol, on cytotoxicity induced by UV irradiation and antioxidants. Anticancer Res 1997;17:2459-63.  Back to cited text no. 13  [PUBMED]    
14.Distelmaier F, Visch HJ, Smeitink JA, Mayatepek E, Koopman WJ, Willems PH. The antioxidant Trolox restores mitochondrial membrane potential and Ca2+-stimulated ATP production in human complex I deficiency. J Mol Med 2009;87:515-22.  Back to cited text no. 14  [PUBMED]  [FULLTEXT]  
15.Raspor P, Plesnicar S, Gazdag Z, Pesti M, Miklavcic M, Lah B, et al. Prevention of intracellular oxidation in yeast: The role of vitamin E analogue, Trolox (6-hydroxy-2,5,7,8-tetramethylkroman-2-carboxyl acid. Cell Biol Int 2005;29:57-63.  Back to cited text no. 15  [PUBMED]    
16.Poljsak B, Gazdag Z, Pesti M, Filipic M, Fujs S, Farkas N, et al. Role of the vitamin E model compound Trolox in the prevention of Cr(VI)-induced cellular damage. Toxicol Environ Chem 2006;88:141-57.  Back to cited text no. 16      
17.Pekmez M, Arda N, Hamad I, Kig C, Temizkan G. Hydrogen peroxide-induced oxidative damages in Schizosaccharomyces pombe. Biologia 2008;63:151-5.  Back to cited text no. 17      
18.Pick E, Keisari Y. A simple colorimetric method for the measurement of hydrogen peroxide produced by cells in culture. J Immunol Methods 1980;38:161-70.  Back to cited text no. 18  [PUBMED]  [FULLTEXT]  
19.Okai Y, Higashi-Okai K, Machida K, Nakamura H, Nakayama K, Fujita K, et al. Protective effect of antioxidants against para-nonylphenol-induced inhibition of cell growth in Saccharomyces cerevisiae. FEMS Microbiol Lett 2000;185:65-70.  Back to cited text no. 19  [PUBMED]    
20.Forsburg LS, Rhind N. Basic methods for fission yeast. Yeast 2006;23:173-83.  Back to cited text no. 20      
21.Waterborg JH. Protein protocols handbook. Chapter 2, The Lowry method for protein quantitation. 2 nd ed. New Jersey: Humana Press; 2002. p. 7-9.  Back to cited text no. 21      
22.Cho YW, Park EH, Lim CJ. Catalase, glutathione S-transferase and thioltransferase respond differently to oxidative stress in Schizosaccharomyces pombe. J Biochem Mol Biol 2000;33:344-8.  Back to cited text no. 22      
23.Dunn MJ. The protein protocols handbook. Chapter 33 Detection of proteins in polyacrylamide gels by silver staining. 2 nd ed. New Jersey: Humana Press; 2002. p. 265-72.  Back to cited text no. 23      
24.Reinheckel T, Grune T, Davies KJ. Stress response: Methods and protocols. Methods in Molecular Biology. Chapter 5, The measurement of protein degradation in response to oxidative stress. Vol. 99. New Jersey: Humana Press; 2000. p. 49-60.   Back to cited text no. 24      
25.Bronzetti G, Cini M, Andreoli E, Caltavuturo L, Panunzio M, Croce CD. Protective effects of vitamins and selenium compounds in yeast. Mutat Res 2001;496:105-15.  Back to cited text no. 25      
26.Peus D, Meves A, Pott M, Beyerle A, Pittelkow MR. Vitamin E analog modulates UVB-induced signaling pathway activation and enhances cell survival. Free Radic Biol Med 2001;30:425-32.  Back to cited text no. 26      
27.Susa N, Ueno S, Furukawa Y, Sugiyama M. Protective effects of vitamin E on chromium (VI)-induced cytotoxicity and lipid peroxidation in primary cultures of rat hepatocytes. Arch Toxicol 1996;71:20-4.  Back to cited text no. 27      
28.Inai Y, Nishikimi M. Increased degradation of oxidized proteins in yeast defective in 26S proteasome assembly. Arch Biochem Biophys 2002;404:279-84.  Back to cited text no. 28      
29.Reinheckel T, Ullrich O, Sitte N, Grune T. Differential impairment of 20S and 26S proteasome activities in human hematopoietic K562 cells during oxidative stress. Arch Biochem Biophys 2000;377:65-8.  Back to cited text no. 29      


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1]


This article has been cited by
1 Loperamide, pimozide, and STF-62247 trigger autophagy-dependent cell death in glioblastoma cells
Svenja Zielke,Nina Meyer,Muriel Mari,Khalil Abou-El-Ardat,Fulvio Reggiori,Sjoerd J. L. van Wijk,Donat Kögel,Simone Fulda
Cell Death & Disease. 2018; 9(10)
[Pubmed] | [DOI]
2 CDK4/6 and autophagy inhibitors synergistically induce senescence in Rb positive cytoplasmic cyclin E negative cancers
Smruthi Vijayaraghavan,Cansu Karakas,Iman Doostan,Xian Chen,Tuyen Bui,Min Yi,Akshara S. Raghavendra,Yang Zhao,Sami I. Bashour,Nuhad K. Ibrahim,Meghan Karuturi,Jing Wang,Jeffrey D. Winkler,Ravi K. Amaravadi,Kelly K. Hunt,Debu Tripathy,Khandan Keyomarsi
Nature Communications. 2017; 8: 15916
[Pubmed] | [DOI]
3 Selenium- and Tellurium-Based Antioxidants for Modulating Inflammation and Effects on Osteoblastic Activity
Xi Lu,Gemma Mestres,Vijay Singh,Pedram Effati,Jia-Fei Poon,Lars Engman,Marjam Ott
Antioxidants. 2017; 6(1): 13
[Pubmed] | [DOI]
4 The Combination of Physical Exercise with Muscle-Directed Antioxidants to Counteract Sarcopenia: A Biomedical Rationale for Pleiotropic Treatment with Creatine and Coenzyme Q10
Michele Guescini,Luca Tiano,Maria Luisa Genova,Emanuela Polidori,Sonia Silvestri,Patrik Orlando,Carmela Fimognari,Cinzia Calcabrini,Vilberto Stocchi,Piero Sestili
Oxidative Medicine and Cellular Longevity. 2017; 2017: 1
[Pubmed] | [DOI]
5 Methotrexate induced mitochondrial injury and cytochrome c release in rat liver hepatocytes
Abdullah Al Maruf,Peter J. O’Brien,Parvaneh Naserzadeh,Rozhina Fathian,Ahmad Salimi,Jalal Pourahmad
Drug and Chemical Toxicology. 2017; : 1
[Pubmed] | [DOI]
6 Polyphenols of virgin coconut oil prevent pro-oxidant mediated cell death
Soorya Parathodi Illam,Arunaksharan Narayanankutty,Achuthan C. Raghavamenon
Toxicology Mechanisms and Methods. 2017; : 1
[Pubmed] | [DOI]
7 Cervical spinal cord injury exacerbates ventilator-induced diaphragm dysfunction
Ashley J. Smuder,Elisa J. Gonzalez-Rothi,Oh Sung Kwon,Aaron B. Morton,Kurt J. Sollanek,Scott K. Powers,David D. Fuller
Journal of Applied Physiology. 2016; 120(2): 166
[Pubmed] | [DOI]
8 T-2 toxin-induced cytotoxicity and damage on TM3 Leydig cells
Zhihang Yuan,Froilan Bernard Matias,Jin-e Yi,Jing Wu
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 2016; 181-182: 47
[Pubmed] | [DOI]
9 Intracellular Antioxidant Activity of Grape Skin Polyphenolic Extracts in Rat Superficial Colonocytes: In situ Detection by Confocal Fluorescence Microscopy
M. Elena Giordano,Ilaria Ingrosso,Trifone Schettino,Roberto Caricato,Giovanna Giovinazzo,M. Giulia Lionetto
Frontiers in Physiology. 2016; 7
[Pubmed] | [DOI]
10 Insight into the messenger role of reactive oxygen intermediates in immunostimulated hemocytes from the scallop Argopecten purpuratus
Daniel Oyanedel,Roxana Gonzalez,Katherina Brokordt,Paulina Schmitt,Luis Mercado
Developmental & Comparative Immunology. 2016; 65: 226
[Pubmed] | [DOI]
11 Pseudopterosin A: Protection of Synaptic Function and Potential as a Neuromodulatory Agent
Stacee Caplan,Bo Zheng,Ken Dawson-Scully,Catherine White,Lyndon West
Marine Drugs. 2016; 14(3): 55
[Pubmed] | [DOI]
12 Targeted CFTR gene disruption with zinc-finger nucleases in human intestinal epithelial cells induces oxidative stress and inflammation
Marie-Laure Kleme,Alain Théophile Sané,Carole Garofalo,Emile Levy
The International Journal of Biochemistry & Cell Biology. 2016; 74: 84
[Pubmed] | [DOI]
13 Recent advances of chroman-4-one derivatives: Synthetic approaches and bioactivities
Saeed Emami,Zahra Ghanbarimasir
European Journal of Medicinal Chemistry. 2015; 93: 539
[Pubmed] | [DOI]
14 Can Antioxidants Protect Against Disuse Muscle Atrophy?
Scott K. Powers
Sports Medicine. 2014; 44(S2): 155
[Pubmed] | [DOI]
15 Flutamide-Induced Cytotoxicity and Oxidative Stress in anIn VitroRat Hepatocyte System
Abdullah Al Maruf,Peter O’Brien
Oxidative Medicine and Cellular Longevity. 2014; 2014: 1
[Pubmed] | [DOI]
16 Ribosomal Protein Mutations Induce Autophagy through S6 Kinase Inhibition of the Insulin Pathway
Harry F. Heijnen,Richard van Wijk,Tamara C. Pereboom,Yvonne J. Goos,Cor W. Seinen,Brigitte A. van Oirschot,Rowie van Dooren,Marc Gastou,Rachel H. Giles,Wouter van Solinge,Taco W. Kuijpers,Hanna T. Gazda,Marc B. Bierings,Lydie Da Costa,Alyson W. MacInnes,Gregory S. Barsh
PLoS Genetics. 2014; 10(5): e1004371
[Pubmed] | [DOI]
17 Apoptotic Cell Death in Cultured Cardiomyocytes Following Exposure to Low Concentrations of 4-Hydroxy-2-nonenal
María P. Hortigón-Vinagre,Fernando Henao
Cardiovascular Toxicology. 2014;
[Pubmed] | [DOI]
18 Miniature enzyme-based electrodes for detection of hydrogen peroxide release from alcohol-injured hepatocytes
Matharu, Z. and Enomoto, J. and Revzin, A.
Analytical Chemistry. 2013; 85(2): 932-939
[Pubmed]
19 Miniature Enzyme-Based Electrodes for Detection of Hydrogen Peroxide Release from Alcohol-Injured Hepatocytes
Zimple Matharu,James Enomoto,Alexander Revzin
Analytical Chemistry. 2013; 85(2): 932
[Pubmed] | [DOI]
20 Impacts of Select Organic Ligands on the Colloidal Stability, Dissolution Dynamics, and Toxicity of Silver Nanoparticles
Lok R. Pokhrel,Brajesh Dubey,Phillip R. Scheuerman
Environmental Science & Technology. 2013; 47(22): 12877
[Pubmed] | [DOI]



 

Top
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    Abstract
    Introduction
    Materials and Me...
    Results and Disc...
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed6321    
    Printed280    
    Emailed0    
    PDF Downloaded757    
    Comments [Add]    
    Cited by others 20    

Recommend this journal