Antioxidant and lipid peroxidation responses in Mytilus galloprovincialis exposed to mixtures of benzo(a)pyrene and copper

This study aimed to assess the antioxidant system potential and lipid peroxidative effects, in the gill and digestive gland of Mytilus galloprovincialis exposed to individual and binary mixtures of benzo(a)pyrene (BaP) and Cu for 7 days. Data demonstrated that in mussels exposed to BaP antioxidant enzymes (catalase--CAT, total glutathione peroxidase--tGPx, glutathione S-transferase--GST and glutathione reductase--GR) and lipid peroxidation (LPO) increased in the gill. On the contrary, in the digestive gland inhibitory antioxidant effects (superoxide dismutase-SOD, GR, metallothioneins-MT) and no changes in LPO levels were detected. Cu was also a potent oxidant agent since MT and LPO levels increased in mussel gill, despite no LPO effect in the digestive gland. For both single contaminants the organ specificity and distinct physiologic/metabolism roles were evident in terms of antioxidant capacity. Gill SOD inhibition, MT and GST unchanged was a result of "simple independent action" of exposure to BaP and Cu. "Interactions" in the binary mixtures, led to absence of changes in LPO effects. In the digestive gland, BaP and Cu interactions were also responsible for the GST and LPO enhancement (antagonistic effects). The current findings demonstrate the differences in antioxidant responses where the organ dependency highlights each contaminant particular mode of action. Generally, in the gill "non-interactive" effects occurred with the lowest Cu concentration while "interactions" exist for the mixture with the highest Cu concentrations. In the digestive gland, "interactions" and "no interaction" effects occurred in all the binary mixtures. Complex contaminant mixtures interact differently based on target tissue which may lead to an imbalance in the mussels health status.     

Antioxidant response of the bivalve Pinna nobilis colonised by invasive red macroalgae Lophocladia lallemandii

Invasive species represent a risk to natural ecosystems and a biodiversity hazard. The present work aims to determine the antioxidant enzyme response – superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), the phase II detoxifying enzyme – glutathione S-transferase (GST) – and markers of oxidative damage – thioredoxin reductase (TR) and malondialdehyde (MDA) – in gills and digestive gland of Pinna nobilis and to study the antioxidant response effects in the bivalve colonised by the invasive macroalgae Lophocladia lallemandii. Colonised specimens were collected in a control area without L. lallemandii and another area completely colonised by L. lallemandii. All enzyme activities were found to be present in gills and digestive gland, with some tissue differences. CAT and SOD activities were higher in gills than digestive gland, whereas GST activity and MDA levels were higher in digestive gland. The presence of L. lallemandii induced a significant increase in the activities of antioxidant enzymes in both gills and digestive gland, except for CAT activity in gills. GST and TR activities were also increased in both tissues, as well as the MDA concentration. We can conclude that the presence of L. lallemandii colonising P. nobilis induces a biological stress and oxidative damage to the fan mussel.     

Acute toxicity and cholinesterase inhibition of the nematicide ethoprophos in larvae of gar Atractosteus tropicus (Semionotiformes: Lepisosteidae)

Biomarkers are a widely applied approach in environmental studies. Analyses of cholinesterase (ChE), glutathione S-transferase (GST) and lipid peroxidation (LPO) are biomarkers that can provide information regarding early effects of pollutants at different biochemical levels on an organism. The aim of this study was to evaluate the biomarker approach on a Costa Rican native and relevant species. For this, larvae of gar (Atractosteus tropicus) were exposed to the organophosphorus nematicide, ethoprophos. Acute (96hr) exposure was conducted with pesticide concentrations ranging from 0.1 microg/L to 1 500 microg/L. The 96hr LC50 calculated was 859.7 microg/L. After exposure, three biomarkers (ChE, GST and LPO) were analyzed in fish that survived the acute test. The lowest observed effect concentration (LOEC) regarding ChE activity inhibition was 50 microg/L. This concentration produced a significant inhibition (p<0.05) of the enzyme by 20%. The highest concentration tested without showing any effect on ChE activity and therefore considered as no observed effect concentration (NOEC) was 10 microg/L. Ethoprophos concentration of 400 microg/L caused a ChE inhibition by 79%. In this study, no significant variations (p>0.05) in GST activity and LPO were observed in A. tropicus larvae after exposure to ethoprophos.     

Effects of 17beta-estradiol and 4-nonylphenol on osmoregulation and hepatic enzymes in gilthead sea bream (Sparus auratus)

Sexually immature Sparus auratus were injected intraperitoneally with coconut oil either alone (control) or containing 17beta-estradiol (E2, 10 microg/g body mass) or 4-nonyphenol (4-NP, 100 and 200 microg/g body mass) and sampled 10 days later. Gill and kidney Na(+),K(+)-ATPase activities, plasma levels of E2 and cortisol, plasma osmolites (osmolality, sodium and chloride) and metabolites (glucose, lactate, proteins and triglycerides) were examined. Livers were used for measuring hepatosomatic index (HSI) and determinations of the activities of antioxidant defences catalase (CAT) and total glutatione peroxidase (t-GPX), the CYP1A-dependent, 7-ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST). HSI and plasma levels of E2 were significantly increased in E2 -treated fish. E2 treatment enhanced plasma osmolality, glucose, triglycerides and proteins, but had no effect on plasma cortisol, and gill and kidney Na(+),K(+)-ATPase activities. Hepatic activities of EROD, GST and CAT were significantly decreased after E2 administration, whereas t-GPX remained unaffected. Treatment with 200 microg/g 4-NP caused a slight increase in plasma E2 relative to the control group. Plasma glucose and protein levels were not affected by 4-NP, while triglycerides were increased. Fish treated with the higher dose of 4-NP displayed a clear reduction in kidney Na(+),K(+)-ATPase activity, together with increases in plasma osmolality, relative to the control group. High 4-NP also caused a significant decrease in EROD and an increase in GST activity. Our results confirm the regulation of the natural estrogen E2 and the weak xenoestrogen 4-NP on osmoregulation and biotransformation enzymes in a partially similar manner. The actions of xenoestrogens on critical physiological processes may have an ecological significance as it can reduce adaptability and capacity to metabolise xenobiotics under stressful conditions.     

Spatial and seasonal biomarker responses in the clam Ruditapes decussatus

The clam Ruditapes decussatus is an important resource to preserve in coastal lagoon systems around the Mediterranean including the South Portugal. To assess spatial and temporal biomarker responses to contamination in the species, a multibiomarker approach was conducted using antioxidant enzymes, MFO system phase I and II; acetylcholinesterase, metallothionein (MT), δ-aminolevulinic acid dehydratase and lipid peroxidation (LPO). The condition index (CI), metals and polycyclic aromatic hydrocarbons (PAHs) were also determined. The levels of contaminants were not particularly high and the antioxidant enzymes, acetylcholinesterase (AChE), MT in the digestive gland, and δ-aminolevulinic acid dehydratase (ALAD) do not provide a suitable seasonal and spatial discrimination reversely to that regarding CYP450, glutathione-S-transferase (GST), MT in the gills, and LPO in both tissues. However, even those could vary with natural variables that may act as confounding factors. Thus, seasonal variability and natural range of biomarker responses must be carefully and accurately taken into account in ecotoxicological approaches of environmental quality assessment programmes.     

Activity patterns of biotransformation enzymes in juvenile chickens after in ovo dosage of PCB126

Little is known about the correlations between biotransformation enzymes in juvenile birds after exposure to environmental toxicants like PCBs. In this study eggs of domestic chicken (Gallus domesticus) were dosed with PCB126 in concentrations of 0.175-0.325 ng/g egg weight. Liver subcellular fractions were analyzed for activities of Phase 1 and Phase 2 biotransformation enzymes 2 and 5 weeks post-hatch. Ethoxyresorufin O-deethylase (EROD) activity was increased in both the 2-week and 5-week samples. Glutathione-S-transferase (GST) activity was increased in the 2-week samples only, but the 5-week samples showed an overall much higher GST activity, probably as a result of a still developing enzyme expression in maturing chickens. The same pattern was seen in the phenol-type UDP-glucuronosyltransferase (UGT) activity of the control animals. The week two samples showed a positive dose-response relationship for the UGT activity, but after 5 weeks this was reversed, possibly caused by inhibition of hydroxylated PCB metabolites. Phenol-type sulfotransferase (SULT) activities were not significantly correlated with time or dose. There was a strong positive regression between the Ah-receptor mediated EROD and UGT activities. The EROD activities were also positively correlated to the GST activities. Most interesting was a negative correlation between the UGT and SULT activities: an inhibited UGT activity appeared to be compensated by an increased SULT activity.     

Activity of antioxidant enzymes and physiological responses in ark shell,Scapharca broughtonii,exposed to thermal and osmotic stress: Effects on hemolymph and biochemical parameters

Changes in water temperature and salinity are responsible for a variety of physiological stress responses in aquatic organisms. Stress induced by these factors was recently associated with enhanced reactive oxygen species (ROS) generation, which caused oxidative damage. In the present study, we investigated the time-related effects of changes in water temperature and salinity on mRNA expression and the activities of antioxidant enzymes (SOD and CAT) and lipid peroxidation (LPO) in the gills and digestive glands of the ark shell, Scapharca broughtonii. To investigate physiological responses, hydrogen peroxide (H₂O₂), lysozyme activity, aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT) were measured in the hemolymph. Water temperature and salinity changes significantly increased antioxidant enzyme mRNA expression and activity in the digestive glands and gills in a time-dependent manner. H₂O₂ concentrations increased significantly in the high-temperature and hyposalinity treatments. LPO, AspAT and AlaAT levels also increased significantly in a time-dependent manner, while lysozyme activity decreased. These results suggest that antioxidant enzymes play important roles in reducing oxidative stress in ark shells exposed to changes in water temperature and salinity.     

Antitumor and cytotoxic effects of Phyllanthus polyphyllus on Ehrlich ascites carcinoma and human cancer cell lines

To evaluate the antitumor and cytotoxic activity of methanol extract of Phyllanthus polyphyllus (MPP) in mice and human cancer cell lines, the antitumor activity of MPP was evaluated against an Ehrlich ascites carcinoma (EAC) tumor model. The activity was assessed using survival time, hematological studies, lipid peroxidation (LPO), antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione S-transferase (GST), solid tumor mass, and short-term in vitro cytotoxicity. The cytotoxic activity of MPP was evaluated using human breast cancer (MCF7), colon cancer (HT29), and liver cancer (HepG2) cell lines Oral administration of MPP (200 and 300 mg/kg) increased the survival time and significantly reduced the solid tumor volume in a dose-dependent manner. Hematological parameters, protein, and packed cellular volume (PCV), which were altered by tumor inoculation, were restored. MPP significantly decreased the levels of LPO, GPx, GST, and significantly increased the levels of SOD and CAT. In a cytotoxicity study against human cancer cell lines, MPP was found to have IC50 values of 27, 42 and 38 microg/ml on MCF-7, HT-29, and HepG2 cells respectively. MPP possessed significant antitumor and cytotoxic activity on EAC and human cancer cell lines.     

Proteasome and antioxidant responses in Cottus gobio during a combined exposure to heat stress and cadmium

Temperature and trace metals are common environmental stressors, and their importance is increasing due to global climate change and anthropogenic pollution. Oxidative damage and antioxidant properties have been studied in liver and gills of the European bullhead (Cottus gobio) subjected to cadmium (CdCl(2) at nominal concentrations of 0.01 and 1mg/L) for 4 days at either 15°C or 21°C. First, exposure to 1mg Cd/L induced a high mortality rate (67%) in fish held at 21°C. Regarding the antioxidant enzymes, exposure to 0.01 mg Cd/L significantly increased the activity of superoxide dismutase (SOD) and decreased the activity of glutathione reductase (GR) in liver, independently of heat stress. In gills, exposure to 21°C resulted in a significantly increased activity of glutathione peroxidase (GPx), whereas the activity of glutathione S-transferase (GST) was significantly reduced as compared to fish exposed to 15°C. Furthermore, regardless of Cd stress, exposure to elevated temperature resulted in a significant decrease of lipid peroxidation (LPO) level in liver and in a significant increase in the activity of chymotrypsin-like 20S proteasome in both studied tissues of C. gobio. Overall, the present results indicated that elevated temperature and cadmium exposure independently influenced the antioxidant defense system in bullhead with clear tissue-specific and stress-specific antioxidant responses. Further, elevated temperature affected the hepatic lipid peroxidation and the activity of 20S proteasome in both tissues.     

Chloramine T induced oxidative stress and the response of antioxidant system in <Emphasis Type="Italic">Phanerochaete chrysosporium</Emphasis>

In this study, the effect of chloramine T (Chl-T) on the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione S-transferase (GST); the levels of reduced (GSH) and oxidised glutathione (GSSG) and their ratios; and also membrane lipid peroxidation (LPO) levels in Phanerochaete chrysosporium were investigated in a dose- (0.25–1 mmol/L) and time-dependent (1.5–9 h) manner. The highest SOD activity was observed in 0.5 mmol/L Chl-T at 6th hour as 1.48-fold of its control. The observed highest level in CAT activities was 4.6-fold of control in 0.5 and 0.75 mmol/L at the 6th hour. The GSH levels that were over the control showed decreasing tendency from the beginning of incubation, except 0.25 mmol/L. In contrast with GSH level variations, GSSG levels reached 10.0-fold of its control by showing increasing tendency with the increases in concentration and time. While the GSH/GSSG ratios were over the control at 0.25 mmol/L during all incubation, they fell under the control values at the earlier hours of incubation with the increasing concentrations of Chl-T. Glutathione-related enzymes GSH-Px, GR and GST were also induced with Chl-T treatment, and the highest activities were 3.29-, 7.5- and 6.56-fold of their controls, respectively. On the other hand, the increases in LPO levels with increasing concentration and time up to 5.27-fold of its control showed that the inductions observed in antioxidant system could not prevent the Chl-T-based oxidative stress.     

The applicability of acetylcholinesterase and glutathione S-transferase in Daphnia magna toxicity test

The most commonly used toxicity test worldwide is the acute Daphnia magna test. The relevance of acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in D. magna exposed to chromium, cadmium, and diazinon was evaluated in connection with this standard test. We found no link between enzyme activities and immobility. Concentrations of Cr(6+) up to 280 microg/L had no effect on AChE and GST activities, while 20% immobility was observed. At concentrations of 20-25 microg/L of Cd(2+) AChE activity was increased by about 50%. The effect of diazinon on both enzymes was insignificant up to concentrations that caused 27% immobility. Consequently, while the use of AChE and GST activities is recommended when the mode of action of chemicals is studied, the value of these biomarkers in routine acute toxicity tests is limited because the relationship between enzyme activities and immobility of D. magna exposed to different chemicals is unclear.     

Penicillin-induced oxidative stress: effects on antioxidative response of midgut tissues in instars of Galleria mellonella

Penicillin and other antibiotics are routinely incorporated in insect culture media. Although culturing insects in the presence of antibiotics is a decades-old practice, antibiotics can exert deleterious influences on insects. In this article, we test the hypothesis that one of the effects of dietary penicillin is to increase oxidative stress on insects. The effects of penicillin on midgut concentrations of the oxidative stress indicator malondialdehyde (MDA) and on midgut antioxidant enzyme (superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and glutathione peroxidase [GPx]) and transaminases (alanine aminotransferase and aspartate aminotransferase) activities in greater wax moth, Galleria mellonella (L.), were investigated. The insects were reared from first instars on artificial diets containing 0.001, 0.01, 0.1, or 1.0 g penicillin per 100 g of diets. MDA content was significantly increased in the midgut tissues of each larval instar reared in the presence of high penicillin concentrations. Activities of antioxidant and transaminase enzymes did not show a consistent pattern with respect to penicillin concentrations in diet or age of larvae. Despite the increased penicillin-induced oxidative stress in gut tissue, antioxidant and transaminase enzymes did not correlate with oxidative stress level or between each other in larvae of other age stages except for the seventh instar. We found a significant negative correlation of MDA content with SOD and GST activities in seventh instars. SOD activity was also negatively correlated with CAT activity in seventh instars. These results suggest that exposure to dietary penicillin resulted in impaired enzymatic antioxidant defense capacity and metabolic functions in wax moth larval midgut tissues and that the resulting oxidative stress impacts midgut digestive physiology.     

Does starvation influence the antioxidant status of the digestive gland of Nacella concinna in experimental conditions?

In a previous study we analysed the effect of diesel seawater contamination in the digestive gland of the Antarctic limpet Nacella concinna. We observed that antioxidant enzyme activities decreased after one-week starvation prior to the experiment, and this was considered in the analysis of the obtained results. To know whether the digestive gland oxidant-antioxidant status may be altered by starvation and experimental conditions, we evaluated the food deprivation effect in limpets from the nearshore shallow waters of Potter Cove, Antarctica. Organisms were acclimated to laboratory conditions and were divided in fed and starved groups, and maintained in these conditions during one month. Every week 20 limpets were sampled from each group. Digestive glands were dissected and kept frozen until they were processed. Superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) measured as thiobarbituric reactive substances (TBARS), protein oxidation (PO) and reduced glutathione (GSH) were measured. For both groups of limpets, SOD increased its activity in the first week of the exposure period, with a maximum in the second week. CAT activity increased significantly in the second week, only for the starved group. Similarly, GST activity also increased for starved group in the second week; but maintained this tendency for both groups until the fourth week. In fed and starved limpets, TBARS values increased significantly, during the first week and then returned to normal values. The PO levels in the starved group increased only during the first week. The GSH content, for the fed group, increased significantly after the third week. The obtained results indicate that biochemical or physiological studies conducted with N. concinna should consider the effects of food deprivation and time spent under experimental conditions.     

Thyroid hormone-induced haemoglobin changes and antioxidant enzymes response in erythrocytes

Thyroid hormones modulate haemoglobin and reactive oxygen species (ROS) production, leading to antioxidant changes. This study evaluated the antioxidant response to ROS in erythrocytes in hypothyroid and hyperthyroid rats. Wistar rats were divided into four groups: control; hyperthyroid (T4-12 mg 1(-1) in drinking water); sham operated (simulation of thyroidectomy); and hypothyroid (thyroidectomized). Four weeks after, blood was collected and haemoglobin and T(4) levels, lipid peroxidation (LPO), protein oxidation, superoxide dismutase (SOD), catalase (CAT) , glutathione S-transferase (GST) and glutathione peroxidase (GPx) activities, and total radical antioxidant potential (TRAP) were measured. SOD, CAT and GST immunocontent was evaluated. Haemoglobin levels were increased in hyperthyroid erythrocytes. LPO and carbonyls were augmented (65% and 55%, respectively) in hyperthyroid and reduced (31% and 56%, respectively) in hypothyroid group. SOD and CAT activities have not changed, as well as CAT immunocontent. TRAP was diminished in both hyperthyroid and hypothyroid groups (36% and 37%, respectively). GST activity and immunocontent, as well as GPx activity, were increased in hyper and hypothyroid rats. The data suggest that thyroid hormone changes determine ROS concentration changes and decrease of some antioxidant defences that would lead to a compensatory answer of the GST and GPx enzymes, which could be consider as credible biomarkers.     

镉对尖紫蛤抗氧化酶活性及脂质过氧化的影响

为阐明镉(Cd2+)对尖紫蛤消化盲囊和鳃抗氧化酶的毒性影响程度,研究了不同浓度的Cd2+(0.005、0.05、0.5 mg/L)在不同暴露时间(24h、72h、120h)对尖紫蛤鳃和消化盲囊中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-PX)的活性以及丙二醛(MDA)含量的影响。结果表明,在Cd2+浓度为0.005 mg/L时,在整个实验期间Cd2+对消化盲囊和鳃内的SOD、CAT、GSH-PX活性并无显著影响。在Cd2+浓度为0.05 mg/L和0.5 mg/L时,SOD、CAT、GSH-PX在鳃和消化盲囊中的活性都呈现出明显的时间剂量依赖关系。在0.05 mg/L暴露时,鳃和消化盲囊中的SOD、CAT和GSH-PX的活性随时间逐渐增强,在72h时达到最大值,但在120h时略有降低。在0.5 mg/L暴露时,消化盲囊中SOD、CAT及鳃中CAT活性在24h时上升达到最大值,但鳃中SOD直到72h才达到最大值,并均在120h下降到最低,其中消化盲囊中SOD和CAT活性在120h低于对照组,这可能与消化盲囊对Cd2+的敏感性高于鳃有关。在0.5 mg/L暴露的鳃中,GSH-PX在24h、72h活性并不上升,在120h甚至低于正常水平,0.5 mg/L暴露的消化盲囊中,24h时迅速增高,然后逐渐下降到正常值。这可能与Cd2+结合了GSH-PX的活性中心,降低了GSH-PX的活性有关。与3种酶活性随着时间延长和剂量的增加,酶活性会降低的变化趋势不同,鳃和消化盲囊中的MDA的含量随时间延长和剂量的增加而增加,并不出现下降,这表明尖紫蛤鳃和消化盲囊中的MDA含量可以灵敏的反映机体内的氧化损伤程度,但不能敏感的反映水体中Cd2+的污染情况。     

Triiodothyronine and melatonin influence antioxidant defense mechanism in a teleost Anabas testudineus (Bloch): in vitro study

The effect of the hormones triiodothyronine (T3) and melatonin on antioxidant defense system was studied in 6-propyl thiouracil (6-PTU)-treated or photoperiod-exposed teleost Anabas testudineus. 6-PTU (2 microg/g) treatment or photoperiod exposure (24 h) increased malondialdehyde (MDA) and conjugated dienes (CD) concentrations, indicating increased lipid peroxidation (LPO) in the experimental conditions. T3 or melatonin (10(-6) M) treatment for 15 min in vitro in PTU-treated fish reversed the activity of superoxide dismutase (SOD), catalase and glutathione content. T3-treated group showed no change in glutathione peroxidase (GPx) activity, whereas melatonin treatment decreased its activity. T3 inhibited glutathione reductase (GR) activity. Photoperiod exposure (physiological pinealotomy) induced a stressful situation in this teleost, as evidenced by LPO products and antioxidant enzyme activities. Melatonin and T3 treatment for 15 min in vitro also reversed the effect of photoperiod on peroxidation products and the SOD and catalase activities. GR activity decreased in photoperiod-exposed group and melatonin and T3 treatment reversed the activities. The antioxidant enzymes responded to the stress situation after 6-PTU treatment and photoperiod exposure by altering their activities. The study suggested an independent effect of T3 and melatonin on antioxidant defence mechanism in different physiological situations in fish.     

Glutathione S-transferase from the Icelandic scallop (Chlamys islandica): isolation and partial characterization

Glutathione S-transferase from the digestive gland of the cold-adapted marine bivalve Icelandic scallop was purified to apparent homogeneity by single GSTrap chromatography. The enzyme appeared to be a homodimer with subunit M(r) 22,000 having an optimum catalytic activity at pH 6.5-7. Enzymatic analysis of scallop GST using the substrates 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione resulted in apparent values for K(m)(GST) and K(m)(CDNB) of 0.3 mM and 0.4 mM, respectively. The scallop GST lost activity faster than porcine GST when exposed to increased temperatures, but both enzymes needed 10 min incubation at 60 degrees C for complete inactivation. A partial coding sequence was identified in cDNA synthesised from digestive gland mRNA. Comparison to known sequences indicates that the gene product is a glutathione S-transferase, and the predicted Icelandic scallop GST protein scores 40% sequence identity and 60% sequence similarity to mu-class proteins.     

Anticancer potential of rhamnocitrin 4′-β-d-galactopyranoside against N-diethylnitrosamine-induced hepatocellular carcinoma in rats

The hepatoprotective activity of flavonoid rhamnocitrin 4′-β-d-galactopyranoside (RGP) obtained from leaves of Astragalus hamosus L. against N-diethylnitrosamine (DENA)-induced hepatic cancer in Wistar albino rats was evaluated. Hepatic cancer in rats was induced by single-dose intraperitoneal administration of DENA (200 mg/kg). Induction of hepatic cancer was confirmed after 7 days of DENA administration by measurement of elevated level of serum α-feto protein (AFP). Administration of DENA in a single dose lofted the levels of serum biochemical parameters like alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, total protein and AFP. Antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and lipid per oxidation (LPO) were annealed significantly by administration of RGP in a dose-dependant manner. The histopathological examination of rat liver section was found to reinforce the biochemical observations significantly. It was observed that a substantial and dose-dependent reversal of DENA-diminished activity of antioxidant enzymes like SOD, CAT, GPx, GST and the reduced DENA-elevated level of LPO with a marked change. Any elevation in the levels of serum markers along with suppression of free radical formation by scavenging the hydroxyl radicals is significantly prevented by RGP. It also modulates the levels of LPO and perceptibly increases the endogenous antioxidant enzymes level in DENA-induced hepatocellular carcinogenesis. The findings suggest that RGP prevents hepatocellular carcinoma by suppressing the marked increase in the levels of serum marker enzymes, and suppresses the free radical by scavenging hydroxyl radicals.     

The effects of selenium on oxidative stress biomarkers in the freshwater characid fish matrinxã, Brycon cephalus (Günther, 1869) exposed to organophosphate insecticide Folisuper 600 BR (methyl parathion)

Methyl parathion (MP), an organophosphate widely applied in agriculture and aquaculture, induces oxidative stress due to free radical generation and changes in the antioxidant defense system. The antioxidant roles of selenium (Se) were evaluated in Brycon cephalus exposed to 2 mg L(-1) of Folisuper 600 BR (MP commercial formulation - MPc, 600 g L(-1)) for 96 h. Catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) levels in the gills, white muscle and liver were evaluated in fish fed on diets containing 0 or 1.5 mg Se kg(-1) for 8 weeks. In fish treated with a Se-free diet, the MPc exposure increased SOD and CAT activities in all tissues. However, the GPx activity decreased in white muscle and gills whereas no alterations were observed in the liver. MPc also increased GST activity in all tissues with a concurrent decrease in GSH levels. LPO values increased in white muscle and gills and did not change in liver after MPc exposure. A Se-supplemented diet reversed these findings, preventing increases in LPO levels and concurrent decreases in GPx activity in gills and white muscle. Similarly, GSH levels were maintained in all tissue after MPc exposure. These results suggest that dietary Se supplementation protects cells against MPc-induced oxidative stress.