Assessment of genotoxic effects of chloropyriphos and acephate by the comet assay in mice leucocytes

Two organophosphorus (OP) pesticides (chloropyriphos and acephate) and cyclophosphamide (CP) (positive control) were tested for their ability to induce in vivo genotoxic effect in leucocytes of Swiss albino mice using the single cell gel electrophoresis assay or comet assay. The mice were administered orally with doses ranging from 0.28 to 8.96 mg/kg body weight (b. wt.) of chloropyriphos and 12.25 to 392.00 mg/kg b.wt. of acephate. The assay was performed on whole blood at 24, 48, 72 and 96 h. A significant increase in mean comet tail length indicating DNA damage was observed at 24h post-treatment (P<0.05) with both pesticides in comparison to control. The damage was dose related. The mean comet tail length revealed a clear dose dependent increase. From 48 h post-treatment, a gradual decrease in mean tail length was noted. By 96 h of post-treatment the mean comet tail length reached control levels indicating repair of the damaged DNA. From the study it can be concluded that the comet assay is a sensitive assay for the detection of genotoxicity caused by pesticides.     

DNA damage and aberrant crypt foci as putative biomarkers to evaluate the chemopreventive effect of annatto (Bixa orellana L.) in rat colon carcinogenesis

Chemoprevention opens new perspectives in the prevention of cancer and other degenerative diseases. Use of target-organ biological models at the histological and genetic levels can markedly facilitate the identification of such potential chemopreventive agents. Colon cancer is one of the highest incidence rates throughout the world and some evidences have indicated carotenoids as possible agents that decrease the risk of colorectal cancer. In the present study, we evaluate the activity of annatto (Bixa orellana L.), a natural food colorant rich in carotenoid, on the formation of aberrant crypt foci (ACF) induced by dimethylhydrazine (DMH) in rat colon. Further, we investigate, the effect of annatto on DMH-induced DNA damage, by the comet assay. Male Wistar rats were given s.c. injections of DMH (40 mg/kg body wt.) twice a week for 2 weeks to induce ACF. They also received experimental diets containing annatto at 20, 200 or 1000 ppm for five 5 weeks before (pre-treatment), or 10 weeks after (post-treatment) DMH treatment. In both protocols the rats were sacrificed on week 15th. For the comet assay, the animals were fed with the same experimental diets for 2 weeks. Four hours before the sacrifice, the animals received an s.c. injection of DMH (40 mg/kg body wt.). Under such conditions, dietary administration of 1000 ppm annatto neither induce DNA damage in blood and colon cells nor aberrant crypt foci in rat distal colon. Conversely, annatto was successful in inhibiting the number of crypts/colon (animal), but not in the incidence of DMH-induced ACF, mainly when administered after DMH. However, no antigenotoxic effect was observed in colon cells. These findings suggest possible chemopreventive effects of annatto through their modulation of the cryptal cell proliferation but not at the initiation stage of colon carcinogenesis.     

Resveratrol ameliorates DNA damage, prooxidant and antioxidant imbalance in 1,2-dimethylhydrazine induced rat colon carcinogenesis

Colorectal cancer is one of the most common internal malignancies in Western society. Currently oxidative stress has been increasingly postulated as a major contributor to carcinogenesis. The assessment of damage in various biological matrices, such as tissues and cells, is vital to understand the development of carcinogenesis and subsequently devising intervention strategies. Thus, the major objective of the present study was to examine the effect of resveratrol (Res) on DNA damage in a short-term study of 16 days and circulatory lipid peroxidation, enzymic/non-enzymic antioxidants status in a long-term study of 30 weeks in 1,2-dimethylhydrazine (DMH) induced colon carcinogenesis. Wistar male rats were divided into 6 groups, group 1 were control rats, group 2 rats received Res (8 mg/kg body weight, orally, everyday), rats in groups 3–6 were administered (DMH, 20 mg/kg body weight, s.c.) as four injections in order to induce DNA damage in the short-term or once a week for the first 15 weeks in the long-term study. In addition to DMH, group 4 (initiation), 5 (post-initiation) and 6 (entire-period) received Res (8 mg/kg body weight, p.o., everyday). The results revealed that, supplementation with Res (entire-period) treatment regimen significantly reduced the DMH-induced leukocytic DNA damage (tail length, tail moment, % DNA in the comet tail and olive tail moment) as compared to DMH-alone treated rats. In addition, entire-period Res supplementation increased the enzymic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glutathione S-transferase) and non-enzymic (reduced glutathione, vitamin C, vitamin E and β-carotene) antioxidant status with a corresponding decrease in the extent of lipid peroxidation markers (thiobarbituric acid reactive substances, diene conjugates and lipid hydroperoxides). Conversely, Res supplementation during initiation and post-initiation regimen did not produce greater modulatory effects. Our results indicate that DMH-induced DNA damage and oxidative stress were suppressed/prevented effectively by chronic Res supplementation.     

The modulatory influence of p-methoxycinnamic acid, an active rice bran phenolic acid, against 1,2-dimethylhydrazine-induced lipid peroxidation, antioxidant status and aberrant crypt foci in rat colon carcinogenesis

We investigated the chemopreventive effect of p-methoxycinnamic acid (p-MCA), an active phenolic acid of rice bran, turmeric, and Kaemperfia galanga against 1,2-dimethylhydrazine-induced rat colon carcinogenesis. Male albino Wistar rats were randomly divided into six groups. Group 1 consisted of control rats that received a modified pellet diet and 0.1% carboxymethyl cellulose. The rats in Group 2 received a modified pellet diet supplemented with p-MCA [80 mg/kg body weight (b.wt.) post-orally (p.o.)] everyday. The rats in Groups 3-6 received 1,2-dimethylhydrazine (DMH) (20 mg/kg b.wt.) via subcutaneous injections once a week for the first 4 weeks; additionally, the rats in Groups 4, 5 and 6 received p-MCA at doses of 20, 40 and 80 mg/kg b.wt./day p.o., respectively, everyday for 16 weeks. The rats were sacrificed at the end of the experimental period of 16 weeks. The DMH-treated rats exhibited an increased incidence of aberrant crypt foci (ACF) development; an increased crypt multiplicity; decreased concentrations of tissue lipid peroxidation markers such as thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxides (LOOH); decreased levels of tissue enzymic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR); and decreased levels of non-enzymic antioxidants such as reduced glutathione (GSH) and vitamins C, E and A in the colon. Supplementation with p-MCA significantly reversed these changes and significantly inhibited the formation of ACF and its multiplicity. Thus, our findings demonstrate that p-MCA exerts a strong chemopreventive activity against 1,2-dimethylhydrazine-induced colon carcinogenesis by virtue of its ability to prevent the alterations in DMH-induced circulatory and tissue oxidative stress and preneoplastic changes. p-MCA was more effective when administered at a dose of 40 mg/kg b.wt. than at the other two doses tested.     

The protection role of heat shock protein 70 (HSP-70) in the testes of cadmium-exposed rats

Cadmium (Cd) is an environmental carcinogenic pollutant known to inactivate several proteins involved in DNA repair systems while at the same time creating an oxidative stress that can result in additional DNA lesions. The testis and the lung are the target organs for cadmium carcinogenesis. Increased production of oxidants in vivo can cause damage to intracellular macromolecules such as DNA, proteins and lipids, which in turn lead to oxidative injury. So, this investigation aimed to evaluate the protective role of L-Carnitine through up regulation of HSPs against DNA damage induced by cadmium chloride. The current study was carried out on forty adult male rats, each with average weight 220-250g., were divided into 4 equal groups. 1(st) group was received saline solution (0.5 ml/100 g body weight) and kept as control. 2(nd) group was received 500mg / kg body weight L-Carnitine intraperitoneally (IP). 3(rd) group was administered 1.2 mg cadmium chloride IP. 4(th) group was received both cadmium chloride and L-Carnitine simultaneously. The comet assay parameters showed significantly increased HSP70 and DNA damage in testis cells after 10 and 56 days in the third group. Meanwhile, HSP70 showed significantly decreased levels after 10 days and 56 days in the fourth group after L-Carnitine treatment simultaneously with cadmium chloride. The results of the present study demonstrate a damaging effect of cadmium chloride on DNA of the testis cells (with low stress response). This damaging effect increases the synthesis of HSP70 that upregulated by L-Carnitine treatment and showed ameliorative effect of the cells for recovery.     

Normal adaptations to exercise despite protection against oxidative stress

It has been reported that supplementation with the antioxidant vitamins C and E prevents the adaptive increases in mitochondrial biogenesis and GLUT4 expression induced by endurance exercise. We reevaluated the effects of these antioxidants on the adaptive responses of rat skeletal muscle to swimming in a short-term study consisting of 9 days of vitamins C and E with exercise during the last 3 days and a longer-term study consisting of 8 wk of antioxidant vitamins with exercise during the last 3 wk. The rats in the antioxidant groups were given 750 mg·kg body wt(-1)·day(-1) vitamin C and 150 mg·kg body wt(-1)·day(-1) vitamin E. In rats euthanized immediately after exercise, plasma TBARs were elevated in the control rats but not in the antioxidant-supplemented rats, providing evidence for an antioxidant effect. In rats euthanized 18 h after exercise there were large increases in insulin responsiveness of glucose transport in epitrochlearis muscles mediated by an approximately twofold increase in GLUT4 expression in both the short- and long-term treatment groups. The protein levels of a number of mitochondrial marker enzymes were also increased about twofold. Superoxide dismutases (SOD) 1 and 2 were increased about twofold in triceps muscle after 3 days of exercise, but only SOD2 was increased after 3 wk of exercise. There were no differences in the magnitudes of any of these adaptive responses between the control and antioxidant groups. These results show that very large doses of antioxidant vitamins do not prevent the exercise-induced adaptive responses of muscle mitochondria, GLUT4, and insulin action to exercise and have no effect on the level of these proteins in sedentary rats.     

Effect of Ruta graveolens L. and Euphorbia peplus L. anti-inflammatory extracts on nutritional status of rats and the safety of their use

A significant increase in body weight with remarkable increase in total food intake and significant increase in protein efficiency ratio were observed following oral administration of R. graveolens ether extract (500 mg/kg body wt) to growing rats for 3 weeks. Serum albumin was significantly decreased after administration of declofenac (15 mg/kg body wt). Albumin/globulin ratio decreased significantly on administration of E. peplus ether extract (500 mg/kg body wt). No significant changes were observed in other biochemical and nutritional parameters on administration of either of the extracts or declofenac. However, only a significant elevation of alkaline phosphatase was noticed during treatment with R. graveolens. The results suggest that both plant extracts have no harmful effect on nutritional status and are safe towards kidney functions, while Euphorbia is more safe than Ruta in relation to liver functions.     

Tomato-oleoresin supplement prevents doxorubicin-induced cardiac myocyte oxidative DNA damage in rats

Doxorubicin (DOX) is an efficient chemotherapeutic agent used against several types of tumors; however, its use is limited due to severe cardiotoxicity. Since it is accepted that reactive oxygen species are involved in DOX-induced cardiotoxicity, antioxidant agents have been used to attenuate its side effects. To determine tomato-oleoresin protection against cardiac oxidative DNA damage induced by DOX, we distributed Wistar male rats in control (C), lycopene (L), DOX (D) and DOX+lycopene (DL) groups. They received corn oil (C, D) or tomato-oleoresin (5mg/kg body wt. day) (L, DL) by gavage for a 7-week period. They also received saline (C, L) or DOX (4mg/kg body wt.) (D, DL) intraperitoneally at the 3rd, 4th, 5th, and at 6th week. Lycopene absorption was checked by HPLC. Cardiac oxidative DNA damage was evaluated by the alkaline Comet assay using formamidopyrimidine-DNA glycosylase (FPG) and endonuclease III (endo III). Cardiomyocyte levels of SBs, SBs FPG and SBs Endo III were higher in rats from D when compared to other groups. DNA damage levels in cardiomyocytes from DL were not different when compared to C and L groups. The viability of cardiomyocytes from D or DL was lower than C or L groups (p<0.01). Lycopene levels (mean+/-S.D.nmol/kg) in saponified hearts were similar between L (47.43+/-11.78) and DL (49.85+/-16.24) groups. Our results showed: (1) lycopene absorption was confirmed by its cardiac levels; (2) DOX-induced oxidative DNA damage in cardiomyocyte; (3) tomato-oleoresin supplementation protected against cardiomyocyte oxidative DNA damage.     

DNA damage in blood leukocytes of individuals with sickle cell disease treated with hydroxyurea

Hydroxyurea (HU) plays an important role in the treatment of patients with sickle cell disease (SCD). Although HU has been associated with an increased risk of leukemia in some patients with myeloproliferative disorders, the mutagenic and carcinogenic potential of HU has not been established. This study investigated levels of DNA damage using the alkaline (pH>13) comet assay to analyze peripheral blood leukocytes sampled from 28 patients with SCD treated with HU (SCHU) and from 28 normal individuals. The damage index (DI) in the SCHU group was significantly higher than in controls (p<0.05). Gender, smoking or age were not associated with DNA damage in controls or SCHU individuals. In the group of SCHU individuals, mean HU dose and DI were positively correlated, and individuals who received a mean dose of >20 mg/kg HU (DI=24.9+/-5.5) showed significantly more DNA damage than those who received < or =20 mg/kg HU (DI=14.6+/-1.8) (p<0.05). Individuals treated for > or =42 months (DI=23.1+/-4.2) showed significantly greater DNA damage than those treated for <42 months (13.6+/-1.9) (p<0.05). DI was inversely correlated with body mass index in the SCHU group.     

Protective effect of Terminalia chebula against experimental myocardial injury induced by isoproterenol

Cardioprotective effect of ethanolic extract of Terminalia chebula fruits (500 mg/kg body wt) was examined in isoproterenol (200 mg/kg body wt) induced myocardial damage in rats. In isoproterenol administered rats, the level of lipid peroxides increased significantly in the serum and heart. A significant decrease was observed in the activity of the myocardial marker enzymes with a concomitant increase in their activity in serum. Histopathological examination was carried out to confirm the myocardial necrosis. T. chebula extract pretreatment was found to ameliorate the effect of isoproterenol on lipid peroxide formation and retained the activities of the diagnostic marker enzymes.     

Effects of acute and chronic administration of fenproporex on DNA damage parameters in young and adult rats

Obesity is a chronic and multifactorial disease, whose prevalence is increasing in many countries. Pharmaceutical strategies for the treatment of obesity include drugs that regulate food intake, thermogenesis, fat absorption, and fat metabolism. Fenproporex is the second most commonly consumed amphetamine-based anorectic worldwide; this drug is rapidly converted in vivo into amphetamine, which is associated with neurotoxicity. In this context, the present study evaluated DNA damage parameters in the peripheral blood of young and adult rats submitted to an acute administration and chronic administration of fenproporex. In the acute administration, both young and adult rats received a single injection of fenproporex (6.25, 12.5 or 25 mg/kg i.p.) or vehicle. In the chronic administration, both young and adult rats received one daily injection of fenproporex (6.25, 12.5, or 25 mg/kg i.p.) or Tween for 14 days. 2 h after the last injection, the rats were killed by decapitation and their peripheral blood removed for evaluation of DNA damage parameters by alkaline comet assay. Our study showed that acute administration of fenproporex in young and adult rats presented higher levels of damage index and frequency in the DNA. However, chronic administration of fenproporex in young and adult rats did not alter the levels of DNA damage in both parameters of comet assay. The present findings showed that acute administration of fenproporex promoted damage in DNA, in both young and adult rats. Our results are consistent with other reports which showed that other amphetamine-derived drugs also caused DNA damage. We suggest that the activation of an efficient DNA repair mechanism may occur after chronic exposition to fenproporex. Our results are consistent with other reports that showed some amphetamine-derived drugs also caused DNA damage.     

Arginine Administration Decreases Cerebral Cortex Acetylcholinesterase and Serum Butyrylcholinesterase Probably by Oxidative Stress Induction

In the present study we investigated the action of vitamins E and C on the inhibition of acetylcholinesterase and butyrylcholinesterase activities provoked by arginine in cerebral cortex and serum of 60-day-old rats. Animals were pretreated for 1 week with daily intraperitoneal administration of saline (control) or vitamins E (40 mg/kg) and C (100 mg/kg). Twelve hours after the last injection, animals received one injection of arginine (0.8 microM/g of body weight) or saline. Results showed that acetylcholinesterase and butyrylcholinesterase activities were decreased in the arginine-treated rats. Furthermore, pretreatment with vitamins E and C prevented these effects. The data indicate that the reduction of acetylcholinesterase and butyrylcholinesterase activities caused by arginine was probably mediated by oxidative stress. Assuming the possibility that these effects might also occur in the human condition, our findings may be relevant to explain, at least in part, the neurological dysfunction associated with hyperargininemia and might support a novel therapeutic strategy to slow the progression of neurodegeneration in this disorder.     

Zea mays L. extracts modify glomerular function and potassium urinary excretion in conscious rats

Diuretic and uricosuric properties have traditionally been attributed to corn silk, stigma/style of Zea mays L. Although the diuretic effect was confirmed, studies of the plant's effects on renal function or solute excretion were lacking. Thus, we studied the effects of corn silk aqueous extract on the urinary excretion of water, Na+, K+, and uric acid. Glomerular and proximal tubular function and Na+ tubular handling were also studied. Conscious, unrestrained adult male rats were housed in individual metabolic cages (IMC) with continuous urine collection for 5 and 3 h, following two protocols. The effects of 25, 50, 200, 350, and 500 mg/kg body wt. corn silk extract on urine volume plus Na+ and K+ excretions were studied in water-loaded conscious rats (2.5 ml/100 g body wt.) in the IMC for 5 h (Protocol 1). Kaliuresis was observed with doses of 350 (100.42 +/- 22.32-120.28 +/- 19.70 microEq/5 h/100 g body wt.; n = 13) and 500 mg/kg body wt. (94.97+/- 29.30-134.32 +/- 39.98 microEq/5h/100 g body wt.; n = 12; p<0.01), and the latter dose resulted in diuresis as well (1.98 +/- 0.44-2.41 +/- 0.41 ml/5 h/100 g body wt.; n = 12; p<0.05). The effects of a 500 mg/kg body wt. dose of corn silk extract on urine volume, Na+, K+ and uric acid excretions, and glomerular and proximal tubular function, were measured respectively by creatinine (Cler) and Li+ (ClLi) clearances and Na+ tubular handling, in water-loaded rats (5 ml/100 g body wt.) in the IMC for 3 h (Protocol 2). Clcr (294.6 +/- 73.2, n = 12, to 241.7 +/- 48.0 microl/ min/100 g body wt.; n = 13; p<0.05) and the Na+ filtered load (41.9 +/- 10.3, n = 12, to 34.3 +/- .8, n = 13, p<0.05) decreased and ClLi and Na+ excretion were unchanged, while K+ excretion (0.1044 +/- 0.0458, n=12, to 0.2289 +/- 0.0583 microEq/min/100 body wt.; n = 13; p<0.001) increased. For Na+ tubular handling, the fractional proximal tubular reabsorption (91.5 +/- 3.5, n = 12, to 87.5 +/- 3.4%; n = 13; p<0.01) decreased, and both fractional distal reabsorptions--I and II--increased (96.5 +/- 1.5, n = 12, to 97.8 +/- 0.9%; n = 13; p<0.01; and 8.2 +/- 3.5, n = 12, to 12.2 +/- 3.4%, n = 13, p<0.01, respectively). To summarize, in water-loaded conscious rats (2.5 ml/100 body wt.), corn silk aqueous extract is diuretic at a dose of 500 mg/kg body wt. and kaliuretic at doses of 350 and 500 mg/kg body wt. In water-loaded conscious rats (5.0 ml/100 g body wt.), corn silk aqueous extract is kaliuretic at a dose of 500 mg/kg body wt., but glomerular filtration and filtered load decrease without affecting proximal tubular function, Na+, or uric acid excretion.     

Protective effect of aminoguanidine against oxidative stress and bladder injury in cyclophosphamide‐induced hemorrhagic cystitis in rat

Cyclophosphamide (CP) is an antineoplastic agent that is used for the treatment of many neoplastic diseases. Hemorrhagic cystitis (HC) is a major dose limiting side effect of CP. Recent studies show that aminogaunidine, an inhibitor of inducible nitric oxide synthase is a potent antioxidant and prevents changes caused by oxidative stress such as depletion of antioxidant activity and tissue injury. The purpose of the study is to investigate the effect of aminoguanidine on parameters of oxidative stress, antioxidant enzymes and bladder injury caused by CP. Adult male rats were randomly divided into four groups. Control rats were administered saline; the AG control group received 200 mg/kg body wt of aminoguanidine; The CP group received a single injection of CP at the dose of 150 mg/kg body wt intraperitoneally. The CP + AG group received aminoguanidine (200 mg/kg body wt) intraperitoneally 1 h before the administration of CP. The rats were sacrificed 16 h after CP/saline administration. The bladder was used for light microscopic studies and biochemical studies. The markers of oxidative damage including protein carbonyl content, protein thiol, malondialdehyde and conjugated dienes were assayed in the homogenates along with the activities of the antioxidant enzymes, superoxide dismutase, glutathione peroxidase, catalase, and glutathione reductase and glutathione S transferase. In the bladders of CP treated rats edema of lamina propria with epithelial and sub‐epithelial hemorrhage was seen. All the parameters of oxidative stress that were studied were significantly elevated in the bladders of CP treated rats. The activities of the antioxidant enzymes were significantly lowered in the bladders of CP treated rats. Aminoguanidine pretreatment prevented CP‐induced oxidative stress, decrease in the activities of anti‐oxidant enzymes and reduced bladder damage. The results of the present study suggest the antioxidant role for aminoguanidine in CP‐induced bladder damage. Copyright © 2008 John Wiley & Sons, Ltd.     

Induction of hepatic drug metabolizing enzymes by DL-methionine in rats

A single intraperitoneal injection of DL-methionine (500 mg/kg body wt.) to adult male Wistar rats was shown to significantly induce all the components of the hepatic microsomal mixed function oxidase system such as NADPH cytochrome C reductase activity, cytochromes P-450 and b₅, as well as activities of drug metabolizing enzymes such as aminopyrine demethylase and uridine 5′ -diphosphate-glucuronosyltransferase. Combined administration of nicotinamide (250 mg/kg body wt.) and DL-methionine (500 mg/kg body wt.) was shown to bring about an additional increase (25-30%) in the activities of these enzymes as compared to their induction on independent administration of the two endobiotics. In rats bearing Yoshida sarcoma (ascites) tumour as well as in normal rats injected with serum from tumour bearing animals, the decreased activities of hepatic mixed function oxidases could be restored to their normal levels by administration of DL-methionine (500 mg/kg body wt.) to these rats. Whereas actinomycin D (1 mg/kg body wt.) had no effect on the increased incorporation of [¹⁴C] labelled leucine into microsomal proteins following administration of nicotinamide, the enhanced incorporation of the label following DL-methionine administration was completely inhibited by the same dose of actinomycin D. Administration of cycloheximide (0·5 mg/kg body wt.) to rats could completely inhibit the increased incorporation of [¹⁴C] leucine into hepatic microsomal proteins following independent administration of nicotinamide and DL-methionine. Similar inhibitory pattern with actinomycin D and cycloheximide was also demonstrated in case of induction of NADPH cytochromeC reductase activity by both these endobiotics.     

Effect of Indigofera tinctoria Linn on liver antioxidant defense system during D-galactosamine/endotoxin-induced acute hepatitis in rodents

Effects of pre-treatment with the alcoholic extract of I. tinctoria (500 mg/kg body wt/day, p.o. for 21 days) on liver antioxidant defense system during acute hepatitis induced by D-galactosamine (D-GalN)/endotoxin (LPS extracted by phenol water method from E. coli serotype 0111.B4; 300 mg and 30 micrograms/kg body wt/day, i.p., 18 hr before the assay) were investigated on the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase, and levels of total reduced glutathione in the liver of normal and experimental groups of male albino rats. Since lipid peroxidation and associated membrane damage is a key feature of D-galN/LPS-induced liver injury, the levels of lipid peroxides, was estimated and used as an index of oxidative stress. D-GalN/endotoxin-induced hepatic damage was manifested by a significant decrease in the activities of antioxidant enzymes, decreased glutathione levels and increased levels of lipid peroxides. I. tinctoria pre-treated rats showed considerable protection against D-galN/endotoxin, induced oxidative stress as evidenced by a significant increase in the activities of all the antioxidant enzymes studied and significant decrease in the levels of lipid peroxides. Results indicate that pretreatment with I. tinctoria extract in rats is very effective in reducing D-GalN/endotoxin-induced oxidative stress suggesting an antioxidant effect.     

Alleviation of lindane induced toxicity in testis of Swiss mice (Mus musculus) by combined treatment with vitamin C, vitamin E and alpha-lipoic acid

Mitigation of lindane induced toxicity in testis of Swiss mice by combined treatment with vitamin C, vitamin E and alpha-lipoic acid has been evaluated. Male healthy mice (40), 8-10 weeks old were randomly selected and divided into 4 groups, control (C); lindane (L); antioxidant (A) and antioxidant plus lindane (A+L). Group C animals were administered only the vehicle (olive oil); in group L lindane was administered orally at a dose of 40 mg/kg body wt.; in group A combination of antioxidants at a dose of 125 mg/kg body wt.(vitamin C: 50 mg/kg body wt., vitamin E: 50 mg/kg body wt. and alpha-lipoic acid: 25 mg/kg body wt.) was administered orally; in group A+L both antioxidants (125 mg/kg body wt.) and lindane (40 mg/kg body wt.) were administered at their respective doses. In group A+L antioxidants were administered 1 h prior to lindane administration. All treatments were continuously given for 60 days. Histopathological changes due to lindane intoxication indicated shrunken and distorted seminiferous tubules, sparse Leydig cells and blood vessels and atrophy in the tissue. The testis weight also decreased significantly. Lindane treated group showed increased lipid peroxidation, whereas glutathione, glutathione peroxidase, superoxide dismutase, catalase and protein were significantly decreased compared to control. Lindane induced damage was minimized by administration of antioxidants. Results suggest that combined pretreatment with antioxidants can alleviate the damage caused to testis by lindane.     

Genotoxic potential of Cotinus coggygria Scop. (Anacardiaceae) stem extract in vivo

The intention was to evaluate the possible in vivo genotoxic potential in different cell-types, of a methanol extract obtained from the plant stem of Cotinus coggygria Scop., using the sex-linked recessive lethal (or SLRL) test and alkaline comet assay. The SLRL test, revealed the genotoxic effect of this extract in postmeiotic and premeiotic germ-cell lines. The comet assay was carried out on rat liver and bone marrow at 24 and 72 h after intraperitoneal administration. For genotoxic evaluation, three concentrations of the extract were tested, viz., 500, 1000 and 2000 mg/kg body weight (bw), based on the solubility limit of the extract in saline. Comet tail moment and total scores in the group treated with 500 mg/kg bw, 24 and 72 h after treatment, were not significantly different from the control group, whereas in the groups of animals, under the same conditions, but with 1000 and 2000 mg/kg bw of the extract, scores were statistically so. A slight decrease in the comet score and tail moment observed in all the doses in the 72 h treatment, gave to understand that DNA damage induced by Cotinus coggygria extract decreased with time. The results of both tests revealed the genotoxic effect of Cotinus coggygria under our experimental conditions.     

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.     

Hepatoprotective effect of aqueous extract of Phyllanthus niruri on nimesulide-induced oxidative stress in vivo

Nimesulide (NIM), an atypical non-steroidal anti-inflammatory drug (NSAID) is also used as analgesic. In the present study, we evaluated its effect on the prooxidant-antioxidant system of liver and the hepatoprotective potential of aqueous extract of the herb Phyllanthus niruri (PN) on NIM-induced oxidative stress in vivo using a murine model, by determining the activities of hepatic anti-oxidant enzymes superoxide dismutase (SOD) and catalase (CAT), levels of reduced glutathione (GSH) and lipid peroxidation (expressed as malonaldialdehyde, MDA). Aqueous extract of PN at a dose of 50 or 100 mg/kg body wt was administered either intraperitoneally or orally for 7 days, before NIM administration at a dose of 8 mg/kg body wt twice daily for 7 days in mice. Animals were sacrificed 24 h after administration of final dose of NIM. In another set of experiments, both aqueous extract of PN (at a dose of 50 or 100 mg/kg body wt) and NIM (8 mg/kg body wt) were administered simultaneously for 7 days. Animals were sacrificed 24 h after administration of final dose of the extract and NIM, liver tissues were collected, and the activities of SOD and CAT and levels of GSH and lipid peroxidation end-product (as MDA), were determined from the livers of all the experimental animals. Appropriate NIM control was maintained for all sets of experiments. NIM administration (8 mg/kg body wt) for 7 days caused significant depletion of the levels of SOD, CAT and reduced GSH, along with the increased levels of lipid peroxidation. Intraperitoneal administration of the extract at a dose of 50 mg/kg body wt for 7 days,. prior to NIM treatment, significantly restored most of the NIM-induced changes and the effect was comparable to that obtained by administering 100 mg/kg body wt of the extract orally. Thus, results suggested that intraperitoneal administration of the extract could protect liver from NIM-induced hepatic damage more effectively than oral administration. Antioxidant property of the aqueous extract of PN was also compared with that of a known potent antioxidant, vitamin E. The PN extract at a dose of 100 mg/kg body wt along with NIM was more effective in suppressing the oxidative damage than the PN extract at a dose of 50 mg/kg body wt. Results suggested that beneficial effect of the aqueous extract of PN, probably through its antioxidant property, might control the NIM-induced oxidative stress in the liver.