Analysis of oxidative DNA damage and HPRT mutations in humans after hyperbaric oxygen treatment

DNA damage induced by reactive oxygen species (ROS) seems to play an important role in the induction of mutations and cancer. We have recently shown that hyperbaric oxygen (HBO) treatment of volunteers (i.e., exposure to 100% oxygen at a pressure of 2.5 ATA) induces DNA damage detected in leukocytes with the comet assay. Using formamidopyrimidine-DNA glycosylase (FPG protein) we provided indirect evidence for the induction of oxidative DNA base damage. We now comparatively evaluated FPG-sensitive sites with the comet assay and 7,8-dihydro-8-oxo-deoxyguanosine (8-OHdG) with HPLC analysis after a single HBO. As 8-OHguanine (8-OHgua) is one of the major DNA modifications induced by ROS and a pre-mutagenic lesion, we looked for HBO-induced mutations at the HPRT locus with the T cell cloning test. We also determined the genotypes for glutathione transferases (GST) and tested a possible influence of the GSTM1 and GSTT1 genotypes on the sensitivity of subjects against HBO-induced genotoxicity. Our results indicate that despite a clear induction of FPG-sensitive sites no increased levels of 8-OHdG and no induction of HPRT mutations was detected in lymphocytes after HBO. Furthermore, the DNA effects in the comet assay and the mutant frequencies in the HPRT test seem to be unrelated to the GST genotypes of the test subjects.     

Analysis of oxidative DNA damage and HPRT mutations in humans after hyperbaric oxygen treatment

DNA damage induced by reactive oxygen species (ROS) seems to play an important role in the induction of mutations and cancer. We have recently shown that hyperbaric oxygen (HBO) treatment of volunteers (i.e., exposure to 100% oxygen at a pressure of 2.5 ATA) induces DNA damage detected in leukocytes with the comet assay. Using formamidopyrimidine-DNA glycosylase (FPG protein) we provided indirect evidence for the induction of oxidative DNA base damage. We now comparatively evaluated FPG-sensitive sites with the comet assay and 7,8-dihydro-8-oxo-deoxyguanosine (8-OHdG) with HPLC analysis after a single HBO. As 8-OHguanine (8-OHgua) is one of the major DNA modifications induced by ROS and a pre-mutagenic lesion, we looked for HBO-induced mutations at the HPRT locus with the T cell cloning test. We also determined the genotypes for glutathione transferases (GST) and tested a possible influence of the GSTM1 and GSTT1 genotypes on the sensitivity of subjects against HBO-induced genotoxicity. Our results indicate that despite a clear induction of FPG-sensitive sites no increased levels of 8-OHdG and no induction of HPRT mutations was detected in lymphocytes after HBO. Furthermore, the DNA effects in the comet assay and the mutant frequencies in the HPRT test seem to be unrelated to the GST genotypes of the test subjects.     

Preconditioning with hyperbaric oxygen induces tolerance against oxidative injury via increased expression of heme oxygenase-1 in primary cultured spinal cord neurons

Hyperbaric oxygen (HBO) preconditioning can induce ischemic tolerance in the spinal cord. The effect can be attenuated by the administration of an oxygen free radical scavenger or by inhibition of antioxidant enzymes. However, the mechanism underlying HBO preconditioning of neurons against ischemic injury remains enigmatic. Therefore, in the present study primary cultured spinal cord neurons were treated with HBO and then subjected to a hydrogen peroxide (H(2)O(2)) insult. The results show that H(2)O(2) stimulation of the cultured spinal neurons caused severe DNA damage and decreased cell viability, and that these neurons were well protected against damage after a single exposure to HBO preconditioning (0.35 MPa, 98% O(2), 37 degrees C, 2 h). The protective effect started 4 h after pretreatment and lasted for at least 24 h. The cultured neurons after HBO treatment also exhibited increased heme oxygenase-1 (HO-1) expression at both the protein and mRNA levels, which paralleled the protective effect of HBO. Treatment with tin-mesoporphyrin IX (SnMP), a specific HO-1 inhibitor, before HBO pretreatment abolished the HBO-induced adaptive protection noted in the cultured spinal neurons. In conclusion, HBO preconditioning can protect primary cultured spinal cord neurons against oxidative stress, and the upregulation of HO-1 expression plays an essential role in HBO induced preconditioning effect.     

The effect of vitamin E and plant extract mixture composed of carvacrol, cinnamaldehyde and capsaicin on oxidative stress induced by high PUFA load in young pigs

The objective of our study was to determine the antioxidative potential of a plant extract (PE) mixture composed of carvacrol, capsicum oleoresin and cinnamaldehyde against high n-3 polyunsaturated fatty acid (PUFA)-induced oxidative stress in young pigs. Thirty-two weaned castrated male crossbred pigs (BW 10.9 kg; n = 32) were randomly assigned to four dietary treatments (n = 8). The negative control diet (Cont) contained 17.2% energy from fat. Oxidative stress was induced in three of the four experimental groups with the inclusion of n-3 PUFA rich linseed oil. Linseed oil substituted wheat starch in the diet to elevate the amount of energy from fat to 34.1%. One of these diets served as a positive control (Oil), one was additionally supplemented with 271.2 mg/kg of PE mixture and one with 90.4 mg/kg α-tocopheryl acetate (Vit E). After 14 days of treatment, blood and urine were collected for the determination of lipid peroxidation and DNA damage. Lipid peroxidation was studied by plasma malondialdehyde (MDA) concentrations, 24 h urinary MDA and F2-isoprostane (iPF2α-VI) excretion, total antioxidant status of plasma and glutathione peroxidase assays. Lymphocyte DNA fragmentation and 24 h urinary 8-hydroxy-2'-deoxyguanosine excretion were measured to determine DNA damage. Consumption of n-3 PUFA rich linseed oil increased the amount of MDA in plasma and urine, and induced DNA damage in lymphocytes, but did not elevate the amount of iPF2α-VI excreted in the urine. The supplementation with PE and with Vit E did not reduce MDA levels in plasma and urine, but it decreased the percentage of DNA damage in lymphocytes (P < 0.001). The PE reduced the urinary iPF2α-VI excretion in comparison to the Cont diet. The results show that PE and Vit E supplemented to pigs in concentrations of 271.2 mg/kg and 90.4 mg/kg, respectively, can effectively protect pig's blood lymphocytes against oxidative DNA damage, thus suggesting their potentially beneficial effects on the immune system under dietary-induced oxidative stress.     

Investigations on the mechanism of hyperbaric oxygen (HBO)-induced adaptive protection against oxidative stress

Hyperbaric oxygen (HBO) treatment of cell cultures is a well suited model for studying genetic and cellular consequences of oxidative stress. We have previously shown that exposure of isolated human lymphocytes to HBO induces DNA damage and leads to the development of an adaptive response which protects lymphocytes from oxidative DNA damage induced by a repeated HBO exposure or by treatment with H(2)O(2). Our earlier studies also provided evidence for a functional involvement of the inducible enzyme heme oxygenase-1 (HO-1) in this adaptive protection. In contrast, V79 Chinese hamster cells did neither show a comparable adaptive protection nor an induction of HO-1 after HBO exposure. We now investigated possible mechanism(s) by which HO-1 contributes to an enhanced resistance of lymphocytes against oxidative stress. HO-1 catalyzes the rate-limiting step in heme degradation to form carbon monoxide (CO), biliverdin and free iron. We can now show that supplementation with exogenous CO does not protect V79 cells from HBO-induced oxidative DNA damage suggesting that increased generation of CO cannot account for the observed adaptive protection. On the other hand, HBO-exposed lymphocytes showed a small but reproducible increase in cellular ferritin levels, which might indicate that the underlying protective mechanism is based on an induction of ferritin, which may act antioxidatively by preventing the generation of the DNA-damaging hydroxyl radical via Fenton reaction. Our results further show that isolated lymphocytes also induce HO-1 and develop an adaptive protection when the first HBO exposure does not induce DNA damage, indicating that DNA damage is not the trigger for the development of the adaptive protection.     

Effects of organoselenium compound 2-(5-selenocyanato-pentyl)-benzo[de]isoquinoline 1,3-dione on cisplatin induced nephrotoxicity and genotoxicity: an investigation of the influence of the compound on oxidative stress and antioxidant enzyme system

Cisplatin is one of the most active cytotoxic agents used in the treatment of cancer. However, cisplatin therapy is also associated with severe side effects like nephrotoxicity and genotoxicity. Free oxygen radicals are known to play a major role in cisplatin induced toxicities. Selenium is believed to be an important trace element and dietary antioxidant because of its ability to scavenge free oxygen radicals, thereby preventing cells from oxidative stress. The purpose of this study is to evaluate the protective role of a novel naphthalimide based organoselenium compound 2-(5-selenocyanato-pentyl)-benzo[de]isoquinoline 1,3-dione against cisplatin induced toxicities in Swiss albino mice. Cisplatin was administered intraperitoneally (5 mg/kg b.w.) and the organoselenium compound was given by oral gavages (3 mg/kg b.w.) in concomitant and pretreatment schedule. The results showed that the test compound substantially reduced cisplatin induced reactive oxygen species generation and lipid peroxidation in kidney as well as blood urea nitrogen and creatinine levels in serum. Treatment with organoselenium compound was also able to restore the renal antioxidant system by modulating the cisplatin induced depleted activities of glutathione S-transferase, thioredoxin reductase, superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione level. In addition, the organoselenium compound could efficiently minimize cisplatin induced chromosomal aberrations in bone marrow cells and extent of DNA damage in lymphocytes. Furthermore, the chemoprotective efficacy of the compound against cisplatin induced toxicity was confirmed by histopathological evaluation. The results suggest that the organoselenium compound has the potential to protect against cisplatin induced nephrotoxicity and genotoxicity in part by scavenging reactive oxygen species and by up regulating the antioxidant enzyme system.     

Influence of novel naphthalimide-based organoselenium on genotoxicity induced by an alkylating agent: the role of reactive oxygen species and selenoenzymes

Abstract

Objective

The protection conferred by a series of synthetic organoselenium compounds against genotoxicity and oxidative stress induced by a reference mutagen cyclophosphamide (CP) was assessed.

Method

Genotoxicity was induced in mice by CP treatment (25 mg/kg b.w.) for 10 consecutive days. Organoselenium compounds (3 mg/kg b.w.) were administered orally in a concomitant and pretreatment schedule. DNA damage in peripheral blood lymphocytes and frequency of chromosomal aberration in the bone marrow cells were measured. Liver tissues were collected for analysis of the activity of antioxidant and detoxifying enzymes, lipid peroxidation (LPO) level, glutathione content, and histopathology.

Results

Exposure to CP not only led to a significant increase in the percent of chromosomal aberration and DNA damage, but also enhanced generation of hepatic reactive oxygen species (ROS) and LPO level. The organoselenium compounds demonstrated marked functional protection against CP-induced genotoxicity. DNA damage and chromosomal aberration along with ROS generation were attenuated in the organoselenium-treated mice compared with the CP-treated control mice. CP caused marked depression in the activities of the selenoenzymes (glutathione peroxidase (GPx) and thioredoxin reductase (TRxR)) and other detoxifying and antioxidant enzymes, while treatment with organoselenium compounds restored all these activities towards normal.

Discussion

The protective effect of these compounds may be primarily associated with the improvement of the activity of antioxidant and detoxifying enzymes (including the selenoenzymes, GPx, and TRxR) that are known to protect the DNA and other cellular components from oxidative damage.     

Increased lymphocyte antioxidant defences in response to exhaustive exercise do not prevent oxidative damage

It has been reported that exercise induces oxidative stress and causes adaptations in antioxidant defences. The aim of this study was to determine the adaptations of lymphocytes to the oxidative stress induced by an exhaustive exercise. Nine voluntary male subjects participated in the study. The exercise was a cycling mountain stage (171.8 km), and the cyclists took a mean of 283 min to complete it. Blood samples were taken the morning of the cycling stage day, after overnight fasting, and 3 h after finishing the stage. We determined the blood glutathione redox status (GSSG/GSH), lymphocyte antioxidant enzyme activities and superoxide dismutase (SOD) levels; the plasma and lymphocyte vitamin E levels; the serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities and urate levels; the plasma carotene and malonaldehyde (MDA) levels; and the lymphocyte carbonyl index. The cycling stage induced significant increases in blood-oxidized (glutathione/GSSG), plasma MDA and serum urate levels. The exercise also produced increases in CK and LDH serum activities. The mountain cycling stage induced significant increases in lymphocyte vitamin E levels, glutathione peroxidase and glutathione reductase activities as well as increased SOD activity and protein levels. The protein carbonyl levels increased significantly in lymphocytes after the stage. In conclusion, in spite of increasing antioxidant defences in response to the oxidative stress induced by the exhaustive exercise, lymphocyte oxidative damage was produced after the stage as demonstrated by the increased carbonyl index even in very well trained athletes.     

AZT induces oxidative damage to cardiac mitochondria: protective effect of vitamins C and E

AZT (zidovudine) is a potent inhibitor of HIV replication and a major antiretroviral drug used for AIDS treatment. A major limitation in the use of AZT is the occurrence of severe side effects. The aim of this work was to test whether AZT causes oxidative damage to heart mitochondria and whether this can be prevented by supranutritional doses of antioxidant vitamins. An experimental animal model was used in which mice were treated with AZT for 35 days (10 mg/kg/day) in drinking water. Animals treated with antioxidant vitamins were fed the same diet as controls but supplemented with vitamins C (ascorbic acid, 10 g/ kg diet) and E (alpha-dl-tocopherol, 0.6 g/kg diet) for 65 days before sacrifice. This resulted in a daily intake of 1250 mg/kg/day (vitamin C) and 75 mg/kg/day (vitamin E). Cardiac mitochondrial DNA (mtDNA) of mice treated with AZT had over 120% more oxo-dG (8-oxo-7,8-dihydro-2'-deoxyguanosine, which is a biomarker of oxidative damage to DNA) in their mitochondrial DNA than untreated controls. AZT treatment also caused an increase in mitochondrial lipid peroxidation and an oxidation of mitochondrial glutathione. Dietary supplementation with supranutritional doses of the antioxidant vitamins C and E protected against these signs of mitochondrial oxidative stress. The oxidative effects of AZT are probably due to an increase in production of reactive oxygen species by mitochondria of AZT-treated animals, raising the possibility that oxidative stress may play an important role in the cardiotoxicity of AZT.     

The effect of vitamin E supplementation on reduction of lymphocyte DNA damage induced by T-2 toxin and deoxynivalenol in weaned pigs

The objective of the present study was to establish the effect of deoxynivalenol (DON) and T-2 toxin on lipid peroxidation, lymphocyte DNA fragmentation and immunoglobulin production in weaned pigs, and furthermore, to evaluate the potential of vitamin E (α-tocopheryl acetate) in prevention of toxin mediated changes. Forty-eight weaned castrated male crossbred pigs (mean live weight at the beginning of the experimental period was 11.7 kg) were randomly assigned to five experimental groups: control (without toxin and vitamin E), T-2 (3 mg/kg T-2 toxin), T-2 + E (3 mg/kg T-2 toxin + 100 mg/kg vitamin E), DON (4 mg/kg DON) and DON + E (4 mg/kg DON + 100 mg/kg vitamin E). After 14 days of treatment blood was collected for analysis. Lipid peroxidation was studied by assays of malondialdehyde (MDA), total antioxidant status (TAS) of plasma and erythrocyte glutathione peroxidase (GPx). DNA damage in lymphocytes was measured by comet assay. Serum immunoglobulin levels were evaluated by enzyme-linked immunosorbent assay (ELISA) and the hepatotoxicity was studied by measuring plasma liver enzyme levels (alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamyl-transferase (GGT). Production parameters of both DON groups were significantly impaired in comparison to the control. DON significantly increased the amount of DNA damage in lymphocytes by 28%. Moreover, the levels of TAS were lowered by addition of DON. T-2 toxin significantly impaired daily live weight gain and feed conversion, increased the amount of DNA damage in lymphocytes by 27%, decreased total serum IgG and did not alter plasma TAS. Plasma and 24-h urinary malondialdehyde (MDA) excretion rate and erythrocyte Gpx levels did not differ among the groups. Supplementation with vitamin E did not improve production parameters impaired by DON and T-2 toxin and only partially protected lymphocyte DNA from toxin impact. To our knowledge, these are the first data on genotoxic effects of moderate doses of DON and T-2 toxin on pig lymphocytes. The effect of DON and T-2 toxin on the immune system was reflected as a change in immunoglobulin synthesis, which might be toxin and species specific. According to other results no major induction of oxidative stress could be proven. Enhancement of antioxidant status with vitamin E in the case of DON and T-2 toxin intoxication can be beneficial for remaining the lymphocyte DNA integrity.     

A half-marathon and a marathon run induce oxidative DNA damage, reduce antioxidant capacity to protect DNA against damage and modify immune function in hobby runners

This study investigated whether a 21.1 km (half-marathon) or a 42.195 km (marathon) run modulates DNA damage, antioxidant capacity in lymphocytes and plasma, and the immune system in healthy hobby runners. Ten and 12 volunteers who completed the Baden-Marathon race in Karlsruhe with a running distance of 21.1 km and 41.195 km, respectively, were assessed 10 days before and immediately after the finish. There was no increase in the levels of endogenous DNA strand breaks immediately after half-marathon or marathon races. A statistically significant increase in the levels of oxidative DNA damage in lymphocytes was found using endonuclease III but not formamidopyrimidine glycolase (Fpg). The resistance of DNA to oxidative damage induced by hydrogen peroxide in isolated lymphocytes was significantly decreased after both races. The levels of plasma antioxidants such as alpha-tocopherol, beta-carotene and lycopene were close to, or higher than, those considered optimal for reducing the risk of cardiovascular diseases and there were no significant changes after the races in antioxidant capacity of LDL (lag-time test) or plasma in ORAC, TEAC or paraoxonase assays. The number and percentage of granulocytes and monocytes able to generate oxidative burst were significantly increased after both races, but the lytic activity of NK cells was significantly increased at the end of the half-marathon; no effect was observed in the marathon runners. Thus, oxidative DNA damage in lymphocytes, decreased the antioxidant capacity to protect lymphocytes against DNA strand breaks and increased the formation of reactive species by phagocytes in well-nourished hobby runners indicating moderate oxidative damage during such high-intensity exercise.     

Effectiveness of moderate green tea consumption on antioxidative status and plasma lipid profile in humans

The antioxidant activity of green tea (GT) has been extensively studied; however, the results obtained from dietary intervention studies are controversial. In the present study we investigated the effect of the addition of two cups of GT (containing approximately 250 mg of total catechins) to a controlled diet in a group of healthy volunteers with respect to a group following the same controlled diet but not consuming GT. Antioxidant status and lipid profile in plasma, the resistance from oxidative damage to lipid and DNA, and the activity of glutathione peroxidase (GPX) in isolated lymphocytes were measured at the beginning and the end of the trial. After 42 days, consumption of GT caused a significant increase in plasma total antioxidant activity [from 1.79 to 1.98 micromol Trolox equivalent (TE)/ml, P<.001], significant decreases in plasma peroxides level (from 412 to 288 Carr U, P<.05) and induced DNA oxidative damage in lymphocytes (from 14.2% to 10.1% of DNA in tail, P<.05), a moderate although significant decrease in LDL cholesterol (from 119.9 to 106.6 mg/dL, P<.05) with respect to control. The present study suggests the ability of GT, consumed within a balanced controlled diet, to improve overall the antioxidative status and to protect against oxidative damage in humans.     

Exogenously administered and endogenously produced melatonin reduce hyperbaric oxygen-induced oxidative stress in rat lung

Hyperbaric oxygen (HBO) is a widely used treatment modality in many diseases. A known side effect of HBO is the production of reactive oxygen species. Many antioxidants such as vitamins C and E, riboflavin and selenium have been used successfully to scavenge the reactive oxygen species caused by HBO administration. In this study, we aimed to see if melatonin, a newly discovered antioxidant, has a protective effect against the overproduction of reactive oxygen species produced by HBO in rat lung tissue. Sixty male Sprague-Dawley rats were divided into 5 groups as follows: control, daytime HBO (3 ATA, 120 min), daytime HBO plus melatonin (10 mg/kg), nighttime HBO and nighttime HBO (under light exposure). The MDA, SOD and CAT levels of daytime and nighttime HBO (under light exposure) increased significantly. This significance was not found in the daytime HBO plus melatonin and nighttime HBO groups when compared with the control. In this study, HBO caused oxidant stress, and melatonin decreased the levels of MDA, SOD and CAT. Moreover, endogenous melatonin was found to be a more effective antioxidant than exogenous 10 mg/kg melatonin.     

Influence of an orally effective SOD on hyperbaric oxygen-related cell damage

In a prospective, double-blind, randomised placebo-controlled study, we tested the hypothesis that a new formulation consisting of wheat gliadin chemically combined with a vegetal (thus orally effective) preparation of superoxide dismutase (SOD) allows to prevent hyperbaric oxygen (HBO)-induced oxidative cell stress. Twenty healthy volunteers were exposed to 100% oxygen breathing at 2.5 ATA for a total of 60 min. DNA strand breaks (tail moments) were determined using the alkaline version of the comet assay. Whole blood concentrations of reduced (GSH) and oxidised (GSSG) glutathione and F₂-isoprostanes, SOD, glutathione peroxidase (GPx) and catalase (Cat) activities and red cell malondialdehyde (MDA) content were determined. After HBO exposure the tail moment [Formula: See Text] and isoprostane levels [Formula: See Text] were significantly lower in the group that received the vegetal formulation. Neither SOD and Cat nor GSH and GSSG were significantly affected by this preparation or HBO exposure. By contrast, blood GPx activity, which tended to be lower in the SOD-group already before the HBO exposure [Formula: See Text] was significantly lower afterwards [Formula: See Text] We conclude that an orally effective SOD-wheat gliadin mixture is able to protect against DNA damage, which coincided with reduced blood isoprostane levels, and may therefore be used as an antioxidant.     

Scuba diving enhances endogenous antioxidant defenses in lymphocytes and neutrophils

The aim was to study the effects of a scuba diving session on the lymphocyte antioxidant system, NO synthesis, the capability to produce reactive oxygen species and the antioxidant response in neutrophils. For that purpose seven male divers performed an immersion at a depth of 40 m for 25 min. The same parameters were measured after an hyperbaric oxygen (HBO) treatment at resting conditions in a hyperbaric chamber. Lymphocyte H₂O₂ production rose after diving and after HBO treatment. Glutathione peroxidase (GPx) and catalase activities increased after diving in lymphocytes, while after HBO exposure only increased GPx activity. Lymphocyte HO-1 mRNA expression increased after diving and after HBO exposure, while iNOS levels and nitrite levels significantly increased after diving. The hyperoxia associated to scuba diving leads to a condition of oxidative stress with increased lymphocyte H₂O₂ production, HO-1 expression, NO synthesis and antioxidant enzyme adaptations in order to avoid oxidative damage.     

Comparison between daidzein and genistein antioxidant activity in primary and cancer lymphocytes

The main objective of this study was to compare the protective effect of daidzein and genistein against induced oxidative damage in Jurkat T-cell line and in peripheral blood lymphocytes of healthy subjects. After supplementation of cells with isoflavones (from 2.5 to 20micromol/L in Jurkat T-cell and from 0.01 to 2.5micromol/L in primary lymphocytes, 24h), we determined DNA damage induced by hydrogen peroxide using the comet assay and lipid peroxidation evaluating malondialdehyde (MDA) production after ferrous ion treatment. Supplementation of Jurkat cells and primary lymphocytes with both isoflavones significantly increased DNA protection from oxidative damage at concentrations between 0.1 and 5micromol/L (P<0.05), and with just daidzein, at concentrations higher than 2.5micromol/L, there was a decrease in the production of MDA (P<0.05). Our results seem to support that daidzein is just as effective as genistein in protecting cells against oxidative damage especially with respect to DNA. Moreover, since the protective effect was found at concentrations reachable in plasma after soy consumption (less than 2micromol/L), it can be assumed that the antioxidant activity of isoflavones could really contribute to the healthy properties of soy.     

Protection of peroxide-treated fish erythrocytes by coelenterazine and coelenteramine

European seabass ( Dicentrarchus labrax ) erythrocytes treated with tert -butyl hydroperoxide ( t -BHP) showed decreasing levels of reduced glutathione, increased lipid peroxidation and DNA damage, and ultimately underwent haemolysis. The addition of the marine luciferin coelenterazine (CLZn) markedly delayed the onset of the haemolytic process induced by t -BHP as well as lipid peroxidation and glutathione oxidation. CLZn also protected the red blood cells' DNA against t -BHP-triggered damage. CLZn's oxidation product coelenteramine (CLM) also delayed the lysis of the cells as well as the occurrence of oxidative stress indicators but it did not offer protection against DNA damage. Both compounds proved more efficient than the vitamin E analogue Trolox C ® at similar doses. These results demonstrate the ability of CLZn and CLM to protect fish cells against oxidative stress, providing further support to the evolutionary model suggesting that CLZn's first physiological role was that of an antioxidant in fish thriving in surface layers of the ocean, later evolving into its light-emitting function in deep-sea species.     

Influence of an Orally Effective SOD on Hyperbaric Oxygen-related Cell Damage

In a prospective, double-blind, randomised placebo-controlled study, we tested the hypothesis that a new formulation consisting of wheat gliadin chemically combined with a vegetal (thus orally effective) preparation of superoxide dismutase (SOD) allows to prevent hyperbaric oxygen (HBO)-induced oxidative cell stress. Twenty healthy volunteers were exposed to 100% oxygen breathing at 2.5 ATA for a total of 60 min. DNA strand breaks (tail moments) were determined using the alkaline version of the comet assay. Whole blood concentrations of reduced (GSH) and oxidised (GSSG) glutathione and F₂-isoprostanes, SOD, glutathione peroxidase (GPx) and catalase (Cat) activities and red cell malondialdehyde (MDA) content were determined. After HBO exposure the tail moment [Formula: See Text] and isoprostane levels [Formula: See Text] were significantly lower in the group that received the vegetal formulation. Neither SOD and Cat nor GSH and GSSG were significantly affected by this preparation or HBO exposure. By contrast, blood GPx activity, which tended to be lower in the SOD-group already before the HBO exposure [Formula: See Text] was significantly lower afterwards [Formula: See Text] We conclude that an orally effective SOD-wheat gliadin mixture is able to protect against DNA damage, which coincided with reduced blood isoprostane levels, and may therefore be used as an antioxidant.     

Protective effect of curcumin on gamma-radiation induced DNA damage and lipid peroxidation in cultured human lymphocytes

The present work is aimed at evaluating the radioprotective effect of curcumin, a naturally occurring phenolic compound on gamma-radiation induced toxicity. The cellular changes were estimated by using lipid peroxidative indices like thiobarbituric acid reactive substances (TBARS), the antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH). The DNA damage was analysed by using cytokinesis blocked micronucleus assay and dicentric aberration (DC). The gamma-radiation at different doses (1, 2 and 4Gy) were found to significantly increase micronuclei (MN), DC frequencies and TBARS level whereas the levels of GSH and antioxidant enzymes were significantly decreased. The maximum damage to lymphocytes was observed at 4Gy irradiation. Curcumin pretreatment (1, 5 and 10microg/ml) significantly decreased the frequency of MN and DC. The levels of TBARS decreased and activities of SOD, CAT and GPx significantly increased along with GSH levels. At 1Gy irradiation all the concentrations of curcumin (1, 5 and 10microg/ml) significantly protected the lymphocytes from radiation damage. At 2Gy irradiation, 5 and 10microg/ml of curcumin showed significant radioprotection. Since the highest damage was observed at 4Gy irradiation both 1 and 5microg/ml of curcumin pretreatment were not sufficient to protect the lymphocytes from radiation damage but 10microg/ml of curcumin significantly protected the cultured lymphocytes from radiation damage. Thus, pretreatment with curcumin gives protection to lymphocytes against gamma-radiation induced cellular damage.