Features of regulating delta sleep-inducing peptide by free radical processes in tissue and erythrocyte membranes in intact animals and under stress

In activity the comparative analysis of metabolic effects delta--sleep inducing peptide (DSIP) in tissues and erythrocytes of intact rats and under cold stress is conducted. The regulation effect of DSIP in attitude of free radical processes will be realised through modulation the prooxidant--antioxidant balance: both for intact animal, and at stress. Exogenous DSIP increases the antioxidant system activity in tissues of brain, liver and blood in standard conditions and under cold stress. The anti-stress effect of DSIP is directed as on increase of power endogenic enzymatic antioxidant system activity, specially glutathione peroxidase activity, and not enzymatic of antioxidant protection. The DSIP renders different influence on activity of prooxidant enzymes: for intact animal boosts the myeloperoxidase activity in blood neutrophils, not rendering essential influencing on the xanthine oxidase activity in tissues of brain, liver and activates the myeloperoxidase activity, depresses the xanthine oxidase activity for rats at stress. The membranotropic effect of DSIP in the norm and under stress is connected to increase of stability of protein--lipid interplays. The membranostabilizing effect of DSIP in conditions of stress is characterized decrease of polarity of lipid phase and negative surface charge of erythrocyte membranes, modified in course of lipid peroxidation.     

Differences in activities of antioxidant superoxide dismutase, glutathione peroxidase and prooxidant xanthine oxidoreductase/xanthine oxidase in the normal corneal epithelium of various mammals

Under normal conditions, antioxidants at the corneal surface are balanced with the production of reactive oxygen species without any toxic effects. Danger from oxidative stress appears when natural antioxidants are overwhelmed leading to antioxidant/prooxidant imbalance. The aim of the present study was to examine the activities of enzymes contributing to the antioxidant/prooxidant balance in normal corneal epithelium of various mammals. The enzyme activities of antioxidant superoxide dismutase and glutathione peroxidase, as well as prooxidant xanthine oxidoreductase/xanthine oxidase were examined using biochemical methods. Results show that superoxide dismutase activity is high in rabbits and guinea pigs, whereas in pigs the activity is low and in cows it is nearly absent. In contrast, glutathione peroxidase activity is high in cows, pigs and rabbits, whereas in guinea pigs the activity is low. As far as prooxidant enzymes are concerned, elevated xanthine oxidoreductase/xanthine oxidase activities were found in rabbits, lower activities in guinea pigs, very low activity in cows and no activity in pigs. In conclusion, the above results demonstrate inter-species variations in activities of enzymes participating in antioxidant/prooxidant balance in the corneal epithelium. It is suggested that the levels of antioxidant and prooxidant enzymes studied in the corneal epithelium might be associated with the diurnal or nocturnal activity of animals. UV rays decompose hydrogen peroxide to damaging hydroxyl radicals and perhaps for this reason large animals with diurnal activity (cow, pig) require more effective peroxide removal (high glutathione peroxidase activity) together with the suppression of peroxide production (low superoxide dismutase activity, low xanthine oxidoreductase activity).     

Free radical mechanism of the cold stress development in rats

Development of cold stress in rats is characterized by sharp activation of lipid peroxidation accompanied by a considerable increase of the diene conjugates level and Schiff bases in tissues of brain, liver and in erythrocytes. There is a shift in the prooxidant--antioxidant balance of the organism in the form of amplification of xanthine oxidase prooxidant enzymatic activity in the brain and liver, and a decrease of myeloperoxidase activity in blood neutrophiles of rats. The attrition at cold stress, mainly, of enzymatic endocellular antioxidant system as the result of inhibition of superoxide dismutase, catalase, glutathione reductase activities in brain, liver and erythrocytes is indemnified by activation of non-enzymatic antioxidant mechanisms. In conditions of cold stress, destabilization of erythrocyte membranes of rats described by a decrease of the microviscosity of protein-lipid contact zones and reduction of degree of immersing of proteins in lipid membrane owing to exhibiting proteins from the hydrophobic zone of membranes, or their aggregate, increase of polarity of lipid phase and negative surface charge, is marked.     

Antioxidants and oxidative stress in exercise

Strenuous exercise increases oxygen consumption and causes disturbance of intracellular pro-oxidant-antioxidant homeostasis. The mitochondrial electron transport chain, polymorphoneutrophil, and xanthine oxidase have been identified as major sources of intracellular free radical generation during exercise. Reactive oxygen species pose a serious threat to the cellular antioxidant defense system, such as diminished reserve of antioxidant vitamins and glutathione, and increased tissue susceptibility to oxidative damage. However, enzymatic and nonenzymatic antioxidants have demonstrated great adaptation to acute and chronic exercise. The delicate balance between pro-oxidants and antioxidants suggests that supplementation of antioxidants may be desirable for physically active individuals under certain physiological conditions by providing a larger protective margin.     

Decreased expression of antioxidant enzymes in the conjunctival epithelium of dry eye (Sjögren's syndrome) and its possible contribution to the development of ocular surface oxidative injuries

Previous studies have described elevated lipid peroxidase, myeloperoxidase and xanthine oxidoreductase/xanthine oxidase levels on the ocular surface of patients suffering from autoimmune dry eye (Sj?gren's syndrome, SS). Reactive oxygen species generated by various enzymatic systems may be dangerous to the eye if they are not sufficiently cleaved by antioxidants. Because antioxidants have not been investigated in dry eye, the aim of this study was to examine the expression of antioxidant enzymes that cleave reactive oxygen species and play a key role in antioxidant protection. Conjunctival epithelial cells of dry eye (SS) patients were obtained by the method of impression cytology using Millicell membranes. Normal eyes served as controls. In the conjunctival epithelium superoxide dismutase, catalase and glutathione peroxidase were examined immunohistochemically. The enzyme expression levels were determined by image analysis and statistical evaluation. In contrast to normal eyes, where antioxidant enzymes were highly expressed in the conjunctival epithelium, in dry eye their expression was much less pronounced in correlation with the increasing severity of dry eye symptoms. Our study suggests that the decreased expression of antioxidant enzymes in dry eye disease (SS) contributes to the development of anterior eye surface oxidative injuries.     

Role of redox imbalance and cytokines in mediating oxidative damage and disease progression of patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disorder wherein the contributory role of oxidative stress has been established in the synovial fluid. As availability of synovial fluid is limited, this study aimed to evaluate in the peripheral blood of patients with RA, the relationship if any, between the extent of oxidative stress in terms of generation of reactive oxygen species (ROS) in neutrophils, plasma NADPH oxidase and myeloperoxidase activity with markers of oxidative damage, circulating cytokines and disease activity score (DAS28). In patients with RA, neutrophils in peripheral blood demonstrated an enhanced generation of ROS, coupled with depletion of free radical scavenging activity. Furthermore, the NADPH oxidase and myeloperoxidase activity was enhanced as were markers of damage. There was a positive correlation between the DAS 28 and generation of ROS, NADPH oxidase and myeloperoxidase activity as also with oxidative stress mediated protein carbonylation. Patients with RA demonstrated an increase in proinflammatory (IL-17, IL-23, and IFN-γ) and some anti-inflammatory (IL-4, IL-5, and TGF-β) cytokines. Although the levels of IL-17 correlated positively with generation of ROS, myeloperoxidase, markers of protein damage and DAS28, IL-23 correlated positively only with protein damage, and negatively with free radical scavenging activity. Importantly, incubation of neutrophils from healthy donors with plasma or SF from patients with RA translated into an enhanced generation of ROS, along with an elevation of intracellular proinflammatory cytokines. Taken together, in patients with RA, circulating neutrophils mediated a shift in the oxidant/antioxidant balance favouring the former, which translated into protein damage and contributed towards disease progression.     

Protective effect of vanadate on oxyradical-induced changes in isolated perfused heart

In order to examine the mechanisms of the beneficial effects of vanadate on cardiac dysfunction in chronic diabetes, rat hearts were perfused with xanthine plus xanthine oxidase, an oxyradical generating system in the absence or presence of vanadate. The heart failed to generate contractile force and increased the resting tension markedly within 5 min of perfusion with xanthine plus xanthine oxidase. These changes were prevented by the addition of 4 M vanadate in the perfusion medium. The protective effects of vanadate on the loss of developed tension and increased resting tension due to xanthine plus xanthine oxidase were dose-dependent (0.1–5 M). Perfusion of the hearts with glucose-free medium did not abolish the protective actions of vanadate. The sarcolemmal Ca²⁺-pump (ATP-dependent Ca²⁺ uptake and Ca²⁺-stimulated ATPase) and Na⁺-dependent Ca²⁺ uptake activities were decreased upon perfusing the hearts with a medium containing xanthine plus xanthine oxidase for 5 min; these effects were prevented by the addition of 2–4 M vanadate in the perfusion medium. The signals for superoxide radicals produced by xanthine plus xanthine oxidase, as detected by electron paramagnetic resonance spectroscopic technique, were inhibited by 5–100 M vanadate. These results suggest that vanadate is an oxyradical scavenger and thus may prevent heart dysfunction under some pathological conditions by its antioxidant action.     

Effect of citrate feeding on free radical induced changes in experimental urolithiasis.

Feeding calculi producing diet (CPD) to rats for 4 weeks produced calcium oxaltate stones. Supplementation of sodium citrate to CPD (c-CPD) prevented stone formation. Except oxalate, the excretion of calcium, phosphorus and magnesium was restored to normal in c-CPD fed rats. The CPD fed rats exhibited increase in glycolic acid oxidase (GAO) and lactate dehydrogenase (LDH) activities and only GAO activity was partially restored in c-CPD fed rats. Kidney sub-cellular fractions of calculi producing diet (CPD) fed rats showed increased susceptibility for lipid peroxidation in presence of promotors. Antioxidant enzyme activities of superoxide dismutase (SOD), catalase and glutathione peroxidase and antioxidant concentrations of reduced glutathione, total thiols, ascorbic acid and vitamin E were significantly decreased while the xanthine oxidase activity, and concentrations of hydroxyl radical, diene conjugates and hydroperoxides were significantly increased in CPD fed rats. The susceptibility to lipid peroxidation, activities of antioxidant enzymes, and the concentration of antioxidants were not normalized by feeding citrate.     

Attenuation of potassium bromate-induced nephrotoxicity by coumarin (1,2-benzopyrone) in Wistar rats: chemoprevention against free radical-mediated renal oxidative stress and tumor promotion response

We report the modulatory effect of coumarin (1,2-benzopyrone) on potassium bromate (KBrO(3)) mediated nephrotoxicity in Wistar rats. KBrO(3) (125 mg/kg body weight, i.p.) enhances gamma-glutamyl transpeptidase, renal lipid peroxidation, xanthine oxidase and hydrogen peroxide (H(2)O(2)) generation with reduction in renal glutathione content and antioxidant enzymes. It also enhances blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and [(3)H]-thymidine incorporation into renal DNA. Treatment of rats orally with coumarin (10 mg/kg body weight and 20 mg/kg body weight) resulted in a significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H(2)O(2) generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Renal glutathione content (P < 0.01) and antioxidant enzymes were also recovered to significant level (P < 0.001). These results show that coumarin may be used as an effective chemopreventive agent against KBrO(3)-mediated renal oxidative stress, toxicity and tumor promotion response in Wistar rats.     

Chemomodulatory effect of Ficus racemosa extract against chemically induced renal carcinogenesis and oxidative damage response in Wistar rats

Ferric nitrilotriacetate (Fe-NTA) is a well-known renal carcinogen. In this communication, we show the chemopreventive effect of Ficus racemosa extract against Fe-NTA-induced renal oxidative stress, hyperproliferative response and renal carcinogenesis in rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances renal lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H(2)O(2)) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. It also enhances blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and thymidine [(3)H] incorporation into renal DNA. It also enhances DEN (N-diethylnitrosamine) initiated renal carcinogenesis by increasing the percentage incidence of tumors. Treatment of rats orally with F. racemosa extract (200 and 400 mg/kg body weight) resulted in significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H(2)O(2) generation, blood urea nitrogen, serum creatinine, renal ODC activity, DNA synthesis (P<0.001) and incidence of tumors. Renal glutathione content (P<0.01), glutathione metabolizing enzymes (P<0.001) and antioxidant enzymes were also recovered to significant level (P<0.001). Thus, our data suggests that F. racemosa extract is a potent chemopreventive agent and suppresses Fe-NTA-induced renal carcinogenesis and oxidative damage response in Wistar rats.     

Antioxidant defenses and lipid peroxidation damage in estivating toads, Scaphiopus couchii

Tissue-specific changes in antioxidant defenses and lipid peroxidation damage were analyzed in spadefoot toads, Scaphiopus couchii, to determine how these responded during estivation, a state of suppressed oxygen consumption. Maximal activities of glutathione-S-transferase, glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase were measured in six organs from 2-month-estivated toads and compared with activities in animals awakened for 10 days after estivation. Activities of many enzymes, particularly the glutathione-linked enzymes, were significantly lower in tissues of estivating toads than in awake toads. This indicates that enzymatic antioxidant defenses are probably modulated in response to the rate of reactive oxygen species generation in tissues, which is proportional to oxygen consumption. Antioxidant enzyme activities were largely insensitive to high urea, which accumulates during estivation, but were inhibited by elevated KCl. Levels of reduced glutathione were also significantly lower in three organs during estivation and all organs, except skeletal muscle, exhibited a higher oxidized/reduced glutathione ratio, indicating a more oxidized state during estivation. Products of lipid peroxidation (conjugated dienes, lipid hydroperoxides) were higher in tissues of estivated than control toads, suggesting accumulated oxidative damage to lipids during dormancy. One enzymatic source of free radical generation, xanthine oxidase, appeared to have little impact because its activity was detectable only in liver and was significantly lower in estivated toads. The data indicate that both enzymatic and metabolite antioxidant defenses in toads are adaptable systems that are modulated in estivating versus awake states. Accepted: 21 October 1997     

Antioxidant levels in tissues of young and adult camels (Camelus dromedarius)

In this study, we measured the concentration of some antioxidant substances in erythrocytes hemolysate, liver, kidney and brain in young and adult camels. It has been found that the activity of the antioxidant enzymes glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD) and the concentration of glutathione, ascorbic acid and alpha-tocopherol are high in both young and adult camels. GSH-Px and CAT activities were higher in adult camels than in the young whereas no significant difference in the activity of SOD between young and adult camels was noticed. Glutathione was present in all tissues studied. Ascorbic acid was found to have significantly higher values in young camels. From this study it could be concluded that, as in other mammals, camel tissues contain a powerful antioxidant system. The liver has the highest contents of antioxidants and antioxidant enzymes indicating that it plays an important role in pro-oxidants detoxification. Age has a variable effect on the antioxidant system in camels.     

Effect of delta sleep-inducing peptide on lipid peroxidation and xanthine oxidase activity in rat tissues during cold stress

I. p. administration of exogenous delta-sleep-inducing peptide (DSIP) decreased the amount of diene conjugates and Schiff bases in the liver and brain in rats. The xanthine oxidase activity, at that, did not change. Cold stress enhanced the xanthine oxidase activity well as the amount of diene conjugates and Schiff bases. Preliminary administration of the delta-sleep-inducing peptide to cold-exposed animals diminished the xanthine oxidase activity and lipid peroxidation in the liver and brain. Protective effects of the DSIP under stress is discussed.     

Effect of normothermic ischemic cardiac arrest and of reperfusion on the free oxygen radical scavenger enzymes and xanthine oxidase (a generator of superoxide anions)

Recent evidence suggests that free oxygen radicals are produced by ischaemic tissues, accounting for at least part of the damage that results. These free oxygen radicals are produced by xanthine oxidase, amongst others, and removed by scavenger enzymes (catalase, superoxide dismutase and glutathione peroxidase) and anti-oxidants. As mitochondria are oxygen-utilising organelles, they are capable of producing free oxygen radicals. Our results indicate that the removal of free oxygen radicals are not diminished during ischaemia, but the activity of the free oxygen radical generator, xanthine oxidase, is increased. This could lead to an increased superoxide anion concentration.     

Effects of several regulatory peptides on the functional activity of the pancreas in acute experimental pancreatitis

The influence of regulatory peptides (somatostatin, calcitonin, and dalargin) on xanthine oxidase activity and lipid peroxidation level in pancreatic tissues as well as on the release of pancreatic enzymes (alpha-amylase, trypsin, lipase, and transamidinase) into blood was studied in 205 rats with experimental acute pancreatitis. Somatostatin and dalargin were shown to have obvious antioxidant effect seen by reduced xanthine oxidase activity and MDA level. All studied peptides stimulate reduced release of pancreatic enzymes. Particularly, reduction of dalargin and somatostatin is caused by inhibition of their synthesis as well as by pancreas protective effect of the peptides. Release of enzymes reduced by calcitonin is probably associated only with inhibition of secretory activity of the pancreas.     

Activity of the glutathione antioxidant system and cytochrome P-450 in rat liver under induction and inhibition of xanthine oxidase

The effects of specific xanthine oxidase induction and inhibition on glutathione antioxidant system activity, lipid peroxidation, cytochrome P-450 quantity and corticosteroids concentration in the rat liver were studied. It was dependence established that there was a straight between xanthine oxidase activity and the activity of glutathione antioxidant system, lipid peroxidation and the ascorbic acid formation. The reciprocal dependence was established between xanthine oxidase activity and the concentrations of cytochrome P-450 and corticosteroids.     

Amperometric biosensor based on a functionalized gold electrode for the detection of antioxidants

A method for the electrochemical detection of antioxidants has been developed, which is based on a radical measurement with a cytochrome c modified electrode. A controlled enzymatic production system for superoxide radicals based on xanthine oxidase was used. The addition of antioxidants facilitated the decomposition of the radical in addition to the spontaneous dismutation. The steady-state of superoxide generation and decomposition was thus shifted to a new situation due to the higher decomposition rate after antioxidant addition. This resulted in a decreased current level at the electrode. Antioxidant activity could be quantified from the response of the sensor electrode by the percentage of the signal decrease. The 50% inhibition value (IC(50)) for different antioxidants was calculated and the antioxidant activity of numerous substances was compared. Thus, a hierarchy of superoxide radical scavenging abilities of flavonoids was established: flavanols>flavonols>flavones>flavonones>isoflavonones.     

Blood reflects tissue oxidative stress depending on biomarker and tissue studied

This study investigated whether selected oxidative stress markers measured in blood adequately reflect redox status in skeletal muscle, heart, and liver. Several markers were determined after implementing two treatments known to affect redox status, namely exercise and allopurinol administration. Xanthine oxidase, thiobarbituric acid-reactive substances (TBARS), protein carbonyls (PC), reduced glutathione (GSH), oxidized glutathione (GSSG), catalase, and total antioxidant capacity were determined in blood, skeletal muscle, heart, and liver. Correlation between blood and tissues in each marker was performed through the Spearman rank correlation coefficient. GSSG in erythrocytes was correlated with all tissues, ranging in the five experimental groups as follows: skeletal muscle r_s = 0.656–0.874, heart r_s = 0.742–0.981, liver r_s = 0.646–0.855. Xanthine oxidase and TBARS measured in blood satisfactorily described the redox status of the heart (0.753–0.964 and 0.705–1.000, respectively) and liver (0.755–0.902 and 0.656–1.000, respectively). Skeletal muscle and heart redox status can be adequately described by PC (0.652–1.000 and 0.656–0.964, respectively), GSH (0.693–1.000 and 0.656–1.000, respectively), and catalase (0.745–1.000 and 0.656–1.000, respectively) measured in blood. In conclusion, this study suggests that a combination of markers measured in blood provides a reliable indication about the redox status in skeletal muscle, heart, and liver.     

Antioxidant activity in vitro of two aromatic compounds from Caesalpinia sappan L

Two antioxidant compounds were isolated from C. sappan L by multiple steps of column chromatography and thin layer chromatography in succession with superoxide scavenging assay as activity monitor. Structures of the two compounds were determined by spectroscopic methods as 1',4'-dihydro-spiro[benzofuran-3(2H),3'-[3H-2]benzopyran]-1',6',6',7'-tetrol (compound 1) and 3-[[4,5-dihydroxy-2(hydroxymethyl) phenyl]-methyl]-2,3-dihydro-3,6-benzofurandiol (compound 2). Characterization of antioxidant properties of these two compounds was done by determining the inhibitory effect on xanthine oxidase activity as well as scavenging effect on superoxide anion and hydroxyl radicals. Our results indicated that compounds 1 and 2 inhibited xanthine oxidase activity and scavenged superoxide anion and hydroxyl radicals. Compounds 1 and 2 possessed similar radical scavenging activities as ascorbic acid, and they were more effective than other well-known antioxidants such as alpha-tocopherol, beta-carotene, and BHT. As inhibitors of free radical formation, compounds 1 and 2 were more effective than all the other antioxidants tested. In conclusion, compounds 1 and 2 can be regarded as primary antioxidants with radical-scavenging and chain-breaking activities as well as secondary antioxidants with inhibitory effect on radical generation.