Changes In Glutathione S-transferase Activity Research Articles

Cemtirestat, an aldose reductase inhibitor and antioxidant compound, induces ocular defense against oxidative and inflammatory stress in rat models for glycotoxicity.

Fructose, endogenously produced as a consequence of activation of the polyol pathway under hyperglycemic conditions, contribute to formation of advanced glycoxidation end products (AGEs) and carbonyl stress. Oxidative stressis increased in diabetes (DM) due to AGEs formation and the utilization of NADPH by aldo-keto reductase, AKR1B1(AR), the first enzyme in polyol pathway. Since inhibition of AR is an attractive approach for the management of diabetic eye diseases, we aimed to compare the effects of a novel AR inhibitor (ARI)/antioxidant (AO) compound cemtirestat on eye tissues with the effects of ARI drug epalrestat and AOagent stobadine in rat model for glycotoxicity. One group of rats was fed high fructose (10% drinking water; 14 weeks), while type-2 DM was induced in the other group of rats with fructose plus streptozotocin (40 mg/kg-bw/day). Diabetic (D) and nondiabetic fructose-fed rats (F) were either untreated or treated with two different doses of cemtirestat (2.5 and 7.5 mg/kg-bw/day), epalrestat (25 and 50 mg/kg-bw/day),or stobadine (25 and 50 mg/kg-bw/day) for 14 weeks. Cemtirestat, epalrestat, and stobadine elaviate the increase in TNF-α, IL-1β, NF-ƙB, and caspase-3 in retina, lens, cornea, and sclera of F and D rats. Both glycotoxicity models resulted in a decrease in GSH to GSSG ratio and a change in glutathione S-transferase activity in eye tissues, but these alterations were improved especially with cemtirestat and stobadine. Lens D-sorbitol of D rats increased more than that of F rats, this increase was only attenuated by cemtirestat and epalrestat. Epalrestat was more effective than cemtirestat and stobadine in inhibiting the increase of vascular endothelial growth factor (VEGF)in the retina of F and D rats. Cemtirestat and stobadine but not epalrestat decreased high level of Nε-(carboxymethyl)lysine in the lens and retina of F and D rats. Cemtirestat is a potential therapeutic in protecting the rat eye against glycotoxicity insults.

Determination of erythrocyte Glutathione S-Transferase activity in individuals with gastric and colon cancer

Glutathione-S-Transferase (GST) in human cells has great importance in the detoxification mechanism of carcinogenic chemicals. Therefore, (GST) may be a useful tumor marker. This study examines whether GST activity in Gastric cancer (GC) and Colon Cancer (CC) is a helpful marker in diagnosing and monitoring the disease course. GST activity was investigated in patients with CC and GC and healthy individuals. Erythrocyte isolation was performed in 3 ml blood samples from volunteers aged 18-75 years. Hemoglobin amounts were determined from the standard graph drawn by monitoring the conversion of methemoglobin to cyanmethemoglobin in the presence of cyanide at 540 nm. Glutathione S-transferase activity was determined by measuring the amount of enzyme that catalyzes 1 µmol of S-(2,4-dinitrophenyl) glutathione formed per minute using 1-Chloro-2,4-Dinitrobenzene. The mean values of GST activities of patients with CC and GC, respectively; (1.28 ± 0.23 U/gHb; 1.20 ± 0.30 U/gHb), were significantly higher when compared to the mean values of healthy individuals with GST activity (0.59 ± 0.13 U/gHb) (p < 0.05). The GST activity of patients with colon cancer, measured as (1.56 ± 0.13 U/gHb) after chemotherapy, was significantly higher than before (1.09 ± 0.12 U/gHb) (p < 0.05). GST activity measured as (1.53± 0.24 U/gHb) after chemotherapy in gastric cancer patients was significantly higher when compared to the value measured before chemotherapy (0.97± 0.12 U/gHb) (p < 0.05). Our results show that the change in GST activity in CC and GC can be used as a biomarker to monitor the disease course and response to chemotherapy.

Evaluation of the effects of two anaesthetic protocols on oxidative status and DNA damage in red-eared sliders (Trachemys scripta elegans) undergoing endoscopic coeliotomy.

The aim of this study was to assess how red-eared sliders (Trachemys scripta elegans) respond to anaesthesia itself and coelioscopy. For that purpose, the turtles were anaesthetised with ketamine-medetomidine or propofol, and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the level of malondialdehyde (MDA) were determined by spectrophotometry. The possible genotoxic effects of the anaesthetic agents were estimated by comet assay. A total of 24 turtles were included in this study. The animals were divided into four groups according to the anaesthetic protocol and according to whether endoscopy would be performed. Significantly decreased activities of CAT were found only in the propofol group and in turtles undergoing coelioscopy. Both anaesthetic protocols induced significantly increased MDA levels, while no differences were observed after the intervention. A significant increase in GST activity was detected in turtles after both anaesthetic protocols, but after coelioscopy significant changes in GST activity were found only in the propofol group. However, no differences in SOD activity and no DNA damages were detected in either group. These findings suggest that ketamine-medetomidine may be more suitable anaesthetic agents in red-eared sliders than propofol.

Decrease in Cellular Nanovesicles Concentration in Blood of Athletes More Than 15 Hours After Marathon.

IntroductionCellular nanovesicles (CNVs), that are shed from cells, have been recognized as promising indicators of health status. We analyzed the effect of long-distance running on concentration of CNVs, along with some standard blood parameters, in 27 athletes two days before and >15 hours after physical effort.MethodsCNVs were isolated by repetitive centrifugation and washing of samples, and assessed by flow cytometry. Cholinesterase (ChE) and glutathione S-transferase (GST) activity were measured spectrophotometrically. Interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) concentrations were measured using enzyme-linked immunosorbent assay (ELISA). C-reactive protein (CRP) was measured with immunoturbidimetric determination and lipidogram parameters were measured by enzymatic colorimetric assay. Flow cytometry was used for blood cell count and mean platelet volume (MPV) measurement.ResultsMore than 15 hours after physical effort a decrease was found in CNVs’ concentration in isolates from blood (46%; p<0.05), in ChE activity in whole blood (47%; p<0.001), in plasma (34%; p<0.01), and in erythrocyte suspension (54%; p<0.001), as well as in GST activity in erythrocyte suspension (16%; p<0.01) and in IL-6 concentration in plasma (63%; p<0.05). We found no change in GST activity in plasma and in TNF-α concentration in plasma. Correlations (>0.8; p<0.001) between CNVs’ concentration and ChE activity, and GST activity, respectively, in erythrocyte suspension were found.ConclusionWe found that >15 hours post-physical effort, CNVs’ concentration was below the initial value, concomitant with other measured parameters: ChE and GST activity as well as IL-6 concentration, indicating a favorable effect of physical effort on health status. CNVs’ concentration and ChE activity in isolates from peripheral blood proved to have potential as indicators of the response of the human body to inflammation after physical effort. Physical activity should be considered as an important factor in preparation of subjects for blood sampling in procedures focusing on CNV-containing diagnostic and therapeutic compounds.

Toxicological effects and bioaccumulation of fullerene C60 (FC60) in the marine bivalve Ruditapes philippinarum

Fullerene C60 (FC60), with its unique physical properties, has been used in many applications in recent decades. The increased likelihood of direct release into the environment has raised interest in understanding the biological effects of FC60 to aquatic organisms. Nowadays, only few studies have analysed FC60 effects and bioaccumulation in marine organisms following in vivo exposure. To provide new data about FC60 toxicity, Ruditapes philippinarum was selected as target species to assess potential adverse effects of the contaminant. Clams were exposed for 1, 3 and 7 days to predicted environmental concentrations of FC60 (1 and 10 μg/L) and cellular and biochemical responses were evaluated in clams’ gills, digestive gland and haemolymph. The FC60 content in gills and digestive gland was determined in all experimental conditions after 7 days of exposure. Results showed an increase in oxidative stress. In particular, a significant modulation in antioxidant enzyme activities, and changes in glutathione S-transferase activity were observed in gills. Moreover, damage to lipids and proteins was detected in FC60-treated (10 µg/L) clams. In digestive gland, slighter variations in antioxidant enzyme activities and damage to molecules were detected. CAT activity was significantly affected throughout the exposure, whereas damage to lipids was evident only at the end of exposure. FC60 accumulation was revealed in both gills and digestive gland, with values up to twelve-fold higher in the latter. Interestingly, haemolymph parameters were slightly affected by FC60 compared to the other tissues investigated. Indeed, only Single Cell Gel Electrophoresis and Neutral Red uptake assays showed increased values in FC60-exposed clams. Moreover, volume and diameter of haemocytes, haemocyte proliferation, and micronucleus assay highlighted significant variations in treated clams, but only in the first phases of exposure, and no changes were detected after 7 days. Our results suggested clam gills as the target tissue for FC60 toxicity under the exposure conditions tested: the high damage detected to lipids and proteins could contribute to long-term problems for the organism.

Changes in Glutathione S-transferase Activity and Total Protein Contents of Labeo rohita

Changes in Glutathione S-transferase Activity and Total Protein Contents of Labeo rohita

A 72-h exposure study with eastern oysters (Crassostrea virginica) and the nanomaterial graphene oxide.

Graphene is a 2-dimensional nanomaterial with unique mechanical, thermal, electrical, and optical properties. With increasing applications of graphene-family nanomaterials (GFNs) in electronics, biomedicine, and surface coatings, concern for their impacts on aquatic ecosystems is rising. Current information on the toxicity of GFNs, including graphene oxide, is scarce. Filter-feeding bivalves, such as eastern oysters, are good models for nanomaterial exposure studies. We present results from a 72-h static renewal oyster study using 1 and 10 mg/L graphene oxide, which, to our knowledge, is the first report on in vivo effects of graphene oxide exposures in marine bivalves. Water samples were analyzed for graphene oxide concentration and size assessments. Gill and digestive gland tissues were evaluated for lipid peroxidation and glutathione-S-transferase (GST) activity. In addition, gill sections were fixed for histopathological analyses. Elevated lipid peroxidation was noted in oysters exposed to 10 mg/L graphene oxide. No significant changes in GST activity were observed, but reduced total protein levels were found in digestive gland tissues of exposed oysters at both concentrations. Loss of mucous cells, hemocytic infiltration, and vacuolation were observed in gills of exposed oysters. The results indicate that short-term graphene oxide exposures can induce oxidative stress and epithelial inflammation and adversely affect overall oyster health. Further investigations regarding the fate and sublethal effects of graphene oxide are critical to understanding the risks associated with a rapidly growing graphene consumer market. Environ Toxicol Chem 2019;38:820-830. Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Laboratory bioassays on the response of honey bee (Apis mellifera L.) glutathione S-transferase and acetylcholinesterase to the oral exposure to copper, cadmium, and lead.

In the present study, the influence of cadmium, copper, and lead on two enzymes often used as biomarkers in toxicological analysis was investigated. Bees were fed with 1M sucrose solution containing 10-fold serial dilutions of CuCl2 (1000mgL-1, 100mgL-1, and 10mgL-1), CdCl2 (0.1mgL-1, 0.01mgL-1, and 0.001mgL-1), or PbCl2 (10mgL-1, 1mgL-1, and 0.1mgL-1) during 48h. Our results showed that the total glutathione S-transferase activity was not changed under the influence of cadmium and lead, and it was decreased with the highest concentration of copper. The level of gene expression of the three analyzed classes of glutathione S-transferase was significantly increased with increasing concentrations of copper and cadmium. Lead did not cause significant changes in glutathione S-transferase activity and gene expression, while it showed biphasic effect on acetylcholinesterase activity: lower concentration of lead, 0.1mgL-1 inhibited and higher dose, 10mgL-1 induced acetylcholinesterase activity in honey bees. Furthermore, our results showed a significant decrease of the acetylcholinesterase activity in honey bees treated with 0.001 and 0.01mgL-1 CdCl2. Our results indicate the influence of cadmium, copper, and lead on GST and AChE in the honey bees. These results form the basis for future research on the impact of metallic trace element pollution on honey bees.

Molecular cloning, identification of GSTs family in sunflower and their regulatory roles in biotic and abiotic stress.

Glutathione-S-transferase (GST) genes exist widely in plants and play major role in metabolic detoxification of exogenous chemical substances and oxidative stress. In this study, 14 sunflower GST genes (HaGSTs) were identified based on the sunflower transcriptome database that we had constructed. Full-length cDNA of 14 HaGTSs were isolated from total RNA by reverse transcription PCR (RT-PCR). Sunflower was received biotic stress (Sclerotinia sclerotiorum) and abiotic stress (NaCl, low-temperature, drought and wound). GST activity was measured by using the universal substrate. The results showed that most of the HaGSTs were up-regulated after NaCl and PEG6000-induced stresses, while a few HaGSTs were up-regulated after S. sclerotiorum, hypothermia and wound-induced stressed, and there was correlation between the changes of GST activity and the expression of HaGSTs, indicating that HaGSTs may play regulatory role in the biotic and abiotic stress responses. 14 HaGSTs from sunflower were identified, and the expression of HaGSTs were tissue-specific and played regulatory roles in both stress and abiotic stress.

Biochemical impacts of the textile dyes Remazol Brillant Blue R and Congo Red on the crayfish Astacus leptodactylus (Decapoda, Astacidae)

In this study, we determined the effects of the textile dyes Remazol Brillant Blue R (RBBR) and Congo Red (CR) on the enzymatic activities of Glutathione S-Transferase (GST), cytochrome P450 (CYP1A1) and Lactate dehydrogenase (LDH), in hepatopancreas of Astacus leptodactylus. The crayfishes were exposed to 0.5, 1.0, and 2.0 mg/l of RBBR or CR, for 24 and 48 h. The recorded GST activity clearly increased after 24 or 48 h exposure to CR, compared to a control group (), but the changes of GST activity depending on time and dose were not statistically significant in the RRBR group (). The activity of CYP1A1 generally decreased, but LDH activity increased in the groups exposed to different doses of CR and RBBR, when compared to their control groups. Detoxification enzymes (as GST, and CYP1A1) and metabolic enzymes (as LDH) can be proven to make useful markers for further evaluating the physiological effects of CR and RBBR on crayfish.

Changes in Glutathione S-Transferase Activity and Parental Care Patterns in a Catfish (Pisces, Ariidae) as a Biomarker of Anthropogenic Impact in a Brazilian Harbor.

Catfish have been used as a model system for studying biochemical mechanisms of biotransformation. The main goal of this study was to identify alterations in hepatic glutathione S-transferase (GST) activity and changes in the parental care pattern of a mouth-brooding catfish, Sciades herzbergii, as a biomarker of anthropogenic impact in a port area on the northeastern coast of Brazil. The fish were sampled from a natural reserve (A1=reference site) and from an industrialized port area (A2=impacted site). Two analyses were carried out: hepatic GST activity and mouth-brooding behavior of males. Catfish collected from the A1 site displayed all stages of gonadal maturation, and some of the adult males were mouth brooding 12-30 embryos. Not all gonadal maturation stages of the catfish were represented at the A2 site, and no mouth-brooding males were observed. GST activity in the liver of S. herzbergii was significantly higher in fish from the impacted site compared with fish from the reference site. Values for the enzymatic activity increased progressively in fish sampled from the reserve area as they became more reproductively mature (immature≤maturing≤mature≤spent). However, the greatest values for GST activity (2.84±0.31μmolmin-1 mg protein-1) among fish sampled from the impacted area were found in (immature) juveniles. These data suggest that changes in hepatic GST activity and mouth-brooding behavior of S. herzbergii can be used as biomarkers of anthropogenic impact.

Serotonin modulation in neonatal age does not impair cardiovascular physiology in adult female rats: Hemodynamics and oxidative stress analysis

AimsThe present study investigates the effects of neonatal serotonin modulation in female rats on cardiac parameters related to hemodynamics and oxidative metabolism in the mature animal. Main methodsFemale Wistar rat pups were administered daily subcutaneous injections of fluoxetine (Fx-treated group) or vehicle solution (Ct-group) from the 1st to 21st day of life. At 60days of age, animals from both groups were either used for cardiovascular evaluation or sacrificed for tissue collection for biochemical assays. Key findingsWe found that body weight in the Fx-treated group was less than that in the control. When analyzing hemodynamic parameters (i.e., arterial blood pressure, heart rate—HR, sympathetic and vagal tonus, or intrinsic HR), we did not observe significant difference in the Fx-treated group. Evaluating oxidative stress in brainstem and heart by measuring carbonyl content and malondialdehyde—MDA formation, we observe a decrease in carbonyl content only in the Fx-treated group (60.3%, in brainstem; 58.2%, in heart), without difference in the MDA levels. This observation is consonant with an increase in superoxide dismutase—SOD and catalase—CAT activity in brainstem and heart in the Fx-treated group (SOD: 82.7% and CAT: 23.7 in brainstem; SOD: 60.6%, and CAT: 40.7 in heart), with no changes in glutathione S-transferase activity and reduced glutathione levels. With regard to oxidative metabolism markers, citrate synthase activity was higher in brainstem in the Fx-treated group (20%). SignificanceOur data suggest that serotonin modulation by Fx-treatment at an early age does not induce hemodynamic alteration, although it modulates oxidative metabolism in cardiac-related tissues.

Biochemical Changes of Glutathione S-Transferase Activity During the Germination of Trifolium alexandrinum

The key objective of this study was to investigate the effect of germination on biochemical and enzymatic antioxidant activities of Trifolium alexandrinum seeds. The T. alexandrinum was chosen for GST purification and characterization due to its highest GST activity and antioxidant capacity, beside its economical importance. Seeds of T. alexandrinum were germinated for 6 days. Changes in glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx) in germinating and dormant seeds of T. alexandrinum were evaluated. Also the changes in the total phenolic and flavonoid contents as well as the antioxidant capacities were monitored for 6 days of germination using spectrophotometeric methods. Simple reproducible procedures for the purification of T. alexandrinum GST from both dormant and 6 days germinated seeds were established using DEAE-Sepharose and Sephadex G-100 columns chromatography. The results showed the presence of three isoenzymes for both dormant and germinated seeds designated as GST1, GST2 and GST3. The major GST of the dormant seed was GST2 while for the germinated one was GST3. Dormant GST2 was expressed as a heterodimer with molecular weight of 27.5 and 28.5 KDa while germinated GST3 was expressed as a homodimer with molecular weight of 27 KDa. Characterization of both dormant GST1 & GST2 and germinated GST2 and GST3 including optimum pH, kinetic parameters [kmGSH of 1.17±0.39, 1.22±0.13, 0.84±0.19, 0.96±0.24mM, respectively and kmCDNB of 0.65±0.095, 0.57±0.11, 0.59±0.14, 1.02±0.18 mM, respectively]. The substrate selectivity using different electrophilic compounds and inhibitor effects were carried out. In opposite to other isoenzymes, germinated GST3 exhibited enzymatic activity towards ethacrynic acid with specific activity of 0.073±0.005 µmol/min/mg protein while cibacron blue was the most potent inhibitor for these isoenzymes.

Perfluorooctane Sulfonamide-Mediated Modulation of Hepatocellular Lipid Homeostasis and Oxidative Stress Responses in Atlantic Salmon Hepatocytes

We have investigated the effects of perfluorooctane sulfonamide (PFOSA) on cellular functions and lipid homeostasis (including β-oxidation) in salmon primary hepatocytes. Salmon hepatocytes were exposed to PFOSA at 0 (control), 2, 20, and 50 μM for 12 and 24 h. Fatty acids (FAs) and lipids were determined by GC-MS; FA elongase (FAE), Δ5-desaturase (FAD5), Δ6-desaturase (FAD6), peroxisome proliferator-activated receptors (PPARs), acyl coenzyme A (ACOX-1), glutathione peroxidase (GPx), catalase (CAT), and glutathione S-transferase (GST) mRNA were analyzed using qPCR. GST activity was analyzed by biochemical assays using 1-chloro-2,4-dinitrobenzene (CDNB) as substrate. Our data showed that PFOSA produced significant changes in FA composition that predominantly involved a decrease (at 12 h) and an increase (at 24 h) in FA methyl esters (FAMEs), MUFA, total PUFA, and (n-3 and n-6) PUFA. Particularly, an increase of α-linolenic acid (ALA; 18:3n-3), eicosapentaenoic acid [EPA; 20:5n-3], and arachidonic acid [ARA: 20:4n-6] with associated increase in FAE, FAD5, and FAD6 mRNA were observed after PFOSA exposure, while cis-13,16-docosadienoic acid (22:2) was significantly decreased. PFOSA produced apparent concentration-dependent increase of PPARα and PPARγ. CAT, GPx, and GST mRNA show that PFOSA produced concentration- and time-specific increase of CAT and GST, but no changes in GST activity were observed. In general, these responses indicate that PFOSA evokes deleterious effects on cellular lipid homeostasis and transcriptional responses that regulate cellular oxidative homeostasis in salmon hepatocytes.

Lipid peroxidation and antioxidative response in Arabidopsis thaliana exposed to cadmium and copper

Formation of lipid hydroperoxides, malondialdehyde (MDA) and hydroxyalkenals (HAEs), membrane damages and antioxidative response of plants expressed as changes in glutathione S-transferase activity (GST) and anthocyanin accumulation were studied in Arabidopsis thaliana (L.) Heynh cv. Columbia plants treated for 7 days with various concentrations: 5, 25, 50, 100 μM Cd and Cu. Increased lipid hydroperoxide content was metal concentration-dependent. The level of MDA + HAE was elevated in Cd- and Cu- treated plants, but it was metal concentration-dependent under Cu stress. Electrolyte leakage measurements showed a larger membrane damage under Cu- than Cd-treatment. In Cu-stressed plants, GST activity was always enhanced in comparison with control, while in plants exposed to Cd it dropped slightly at lower metal concentrations; but at 100 μM Cd it was even higher than in plants treated with the same Cu concentration. Anthocyanin accumulation was considerably higher under Cu than Cd stress. Both lipid peroxidation and antioxidative response was stronger in Cu- than Cd-treated Arabidopsis thaliana plants. Various mechanisms of defense against the lipid peroxidation products, depending on the metal type, are discussed.

The effect of excess Zn on mineral nutrition and antioxidative response in rapeseed seedlings

Zinc (Zn) is a necessary element for plants, but excess Zn can be detrimental. To investigate Zn toxicity, rapeseed ( Brassica napus) seedlings were treated with 0.07–1.12 mM Zn for 7 d. Inhibition of plant growth along with root damage, chlorosis and decreased chlorophyll ( a and b) content in newly expanded leaves (the second and third leaves formed following cotyledons) were found under Zn stress. The Zn content increased in plants under external Zn stress, while concentrations of phosphorus, copper, iron, manganese and magnesium reduced significantly, especially in roots. Meanwhile, increased lipid peroxidation was detected biochemically and histochemically. Compared with controls, NADH oxidase and peroxidase (POD) activity increased in leaves and roots of plants under high Zn, but superoxide dismutase (SOD), catalase and ascorbate peroxidase activities decreased. The changes in glutathione S-transferase activity and in ascorbic acid, dehydroascorbate, non-protein thiols and glutathione contents were also measured under Zn stress. Isoforms of SOD and POD were separated using non-denaturing polyacrylamide gel electrophoresis and their activities were analyzed. Our results suggested that excess Zn exerts its toxicity partially through disturbing nutrient balance and inducing oxidative stress in plants. These data will be helpful for better understanding of toxicity of Zn and the adaptive mechanism in Zn non-hyperaccumulator plants.

Toxic effects of crude-oil-contaminated soil in aquatic environment on Carassius auratus and their hepatic antioxidant defense system

Under the indoor simulant conditions, toxic effects of crude-oil-contaminated soil which was put into aquatic environment on the young fishes Carassius auratus and their hepatic antioxidant system after a 20-d exposure were investigated. Results showed that the relationship between the mortality of C. auratus and the exposed doses could be divided into 3 phases: fishes exposed to the low dose groups (0.5-5.0 g/L) were dead due to the ingestion of crude-oil-contaminated soils in aquatic environment; at the medium dose groups (5.0-25.0 g/L) fishes were dead due to the penetration of toxic substances; at the high dose groups (25.0-50.0 g/L) fishes were dead due to environmental stress. The highest mortality and death speed were found in the 1.0 g/L dose group, and the death speed was sharply increased in the 50.0 g/L dose group in the late phase of exposure. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the content of malaondialdehyde (MDA) in the hepatic tissues of C. auratus were induced significantly. The activity of SOD was increased and then decreased. It was significantly inhibited in the 50.0 g/L dose group. The activity of CAT was highly induced, and restored to a level which is little more than the control when the exposed doses exceeded 10.0 g/L. The activity of GST was the most sensitive, it was significantly induced in all dose groups, and the highest elevation was up to 6 times in the 0.5 g/L dose group comparing with the control. The MDA content was significantly elevated in the 50.0 g/L dose group, and the changes of the MDA content were opposite with the changes of GST activity.

Effects of long-term salicylic acid pre-treatment on tomato ( Lycopersicon esculentum Mill. L.) salt stress tolerance: Changes in glutathione S-transferase activities and anthocyanin contents

The aim of the present study was to investigate the effect of salicylic acid (SA) pre-treatment on the salt stress acclimation of tomato plants ( Lycopersicon esculentum Mill. L. cv. Rio Fuego). The antioxidant defence and detoxifying capacity of the tissues were analysed by measuring the accumulation of soluble, non-enzymatic antioxidants (anthocyanins) and the activities of glutathione S-transferases (GSTs) at low (10 −7 M) and high (10 −4 M) SA concentrations in plants exposed to 100 mM NaCl. GSTs are a diverse group of enzymes that catalyse the detoxification of xenobiotics and other toxic organic compounds, and anthocyanins are among the few endogenous substrates that bind to GSTs and are sequestered to the vacuole. It was found that 10 −4 M SA pre-treatment improved the acclimation of tomato to high salinity. SA pre-treatments increased the accumulation of anthocyanins both in the presence and absence of 100 mM NaCl. The extractable GST activity of tissues increased under salt stress in young leaves and roots of the control and in plants pre-treated with 10 −4 M SA, while the extractable GST activity in these organs was reduced by 10 −7 M SA. It is suggested that elevated GST activity is a prerequisite for successful acclimation to high salinity in tomato plants pre-treated with SA, but it may also be a symptom of tissue senescence.

Detoxification and antioxidant responses in diverse organs of Jenynsia multidentata experimentally exposed to 1,2‐ and 1,4‐dichlorobenzene

We report changes in activities of detoxification and antioxidant enzymes as well as lipid peroxidation levels in liver, gills, and brain of Jenynsia multidentata exposed to 1,2- and 1,4-dichlorobenzene (DCB). Fish were captured at an unpolluted area, transported to the laboratory, and acclimated previous to experiments. Exposures were carried out using 1,2-DCB at 0.5, 1, 5, and 10 mg L(-1) and 1,4-DCB at 0.05, 0.1, 1, and 5 mg L(-1). After 24-h exposure, fish were sacrificed and dissected separating liver, gills, and brain of each fish. Organs were used for enzyme extractions, evaluating antioxidant system through the assay of glutathione reductase, guaiacol peroxidase, glutathione peroxidase, catalase as well as detoxification system by measuring glutathione-S-transferase (GST) activity. Additionally, thiobarbituric acid reactive substances (TBARS) method was used to evaluate the peroxidation of lipids. No changes in GST activity were found in liver of fish exposed to DCBs but in gills and brain of exposed fish. The detoxification system was activated at lower concentrations of 1,2-DCB than 1,4-DCB. Antioxidant response is activated in liver at low DCB concentrations, followed by a drop at highest levels. We also found activation of the antioxidant system in gills and brain of exposed fish. On the other hand, we did not observe changes in TBARS concentrations in liver or gills of exposed fish with respect to controls, but in brain of fish exposed to 1,2-DCB (> or =0.5 mg L(-1)) and 1,4-DCB (5 mg L(-1)). Responses of both detoxification and antioxidant systems of J. multidentata suggest that 1,2-DCB is more toxic than 1,4-DCB to this specie. To the extent of our knowledge, this is the first report of oxidative stress induced by DCBs in fish. Our results evidence that the brain is the organ most severely affected by the oxidative stress caused by DCBs.

The effect of feeding piglets with the diet containing green tea extracts or coumarin on in vitro metabolism of aflatoxin B1 by their tissues

To clarify whether enzymes involved in aflatoxin B1 (AFB1) metabolism in pigs respond to antioxidant agents, the effect of feeding piglets with diets containing green tea extracts (Sunphenon) and coumarin on in vitro AFB1 metabolism by their liver and intestinal tissues was studied. The results showed that coumarin reduced AFB1–DNA adduct formation by both liver and intestinal microsomes, while Sunphenon did not have any effects. Both coumarin and Sunphenon enhanced the glutathione S-transferase (GST) activity to conjugate AFB1 to glutathione GSH in the intestine, although no effects were noted in the liver. Changes of the expression of mRNA of GSTA2 and GSTO1 were not in parallel with the observed changes of GST activity, suggesting that other GST subtypes are involved in the GST activity toward AFB1. As for lipophilic-free AFB1 metabolites, coumarin reduced the liver microsomal conversion of AFB1 to aflatoxin M1 (AFM1) and aflatoxin Q1 (AFQ1), but Sunphenon exerted no effects. Both coumarin and Sunphenon enhanced the conversion of AFB1 to aflatoxicol in the liver. All the results suggest that feeding with a diet containing coumarin affects AFB1 metabolism to enhance AFB1 detoxification through the suppression of P450 enzyme activity in the liver and the enhancement of GST activity in the intestine. Feeding with a diet containing Sunphenon enhances AFB1 detoxification, but the effects are noted mainly in the intestine.