Functioning Of Antioxidant System Research Articles

Oxidative Stress and Hepatotoxicity Induced by Synthetic Pyrethroids-Organophosphate Insecticides Mixture in Rat

The effects of organophosphorus [fenitrothion (FNT)] and pyrethroid (lambda-cyhalothrin (LC)] pesticides mixture on the antioxidant defense system and liver function enzymes in rat liver were assessed. Various concentrations of FNT + LC were incubated with liver homogenate at 37°C for various incubation times. Results showed that FNT plus LC caused a significant concentration-dependent and time-related inhibition of glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activities, and reduction of glutathione (GSH) content. The depletion of GSH might indicate that reactive oxygen species could be involved in the toxic effects of FNT plus LC. In addition, a significant inhibition in transaminases (AST, ALT) and phosphatases (AcP, AlP) activities was observed. On the other hand, FNT + LC increased the activity of lactate dehydrogenase (LDH) and thiobarbituric acid reactive substances (TBARS) levels. It can be concluded that such biomarkers may be used in assessing adverse/toxic effects of pesticides as environmental stressors.

Comparison of the Oxidant-Antioxidant Parameters and Sialic Acid Levels in Renal Transplant Patients and Peritoneal Dialysis Patients

Objective Several studies have shown that in end-stage renal failure, increased oxidative stress and reduced antioxidant system functions may play an important role in inflammation, atherosclerosis, and many other complications. Paraoxonase (PON) and arylesterase (ARE) are antioxidant and malondialdehyde (MDA) an oxidant agent. Increased sialic acid (SyA) levels in uremic patients is an acute-phase response showing tissue and organ damage. The aim of this study was to compare PON, ARE, MDA, and SyA among continuous ambulatory peritoneal dialysis (CAPD) and renal transplant patients. Methods Twenty-six CAPD patients including 7 women and 19 men of overall mean age 40.5 ± 10.66 years were included in this study. There were 28 preemptive transplant patients, namely 6 women and 22 men of overall mean age 36.5 ± 10.97 years. CAPD was the initial sole replacement therapy. Serum PON, ATE, MDA, and SyA levels were measured at 13–15 months of treatment. Results Higher PON ( P = .015) and ARE ( P = .002) and lower MDA ( P = .002) and SyA ( P = .000) values were determined among transplanted compared with CAPD patients. Conclusions In the transplant group, antioxidant parameters were higher and oxidant parameters lower with less activation of SyA than in the CAPD group. We observed that renal transplantation had a constructive effect on the oxidant-antioxidant system and consequent tissue destruction, which were impaired in uremic subjects. This study showed that renal transplantation is a more appropriate replacement treatment than CAPD.

Antisense inhibition of a spermidine synthase gene highlights the role of polyamines for stress alleviation in pear shoots subjected to salinity and cadmium

Three transgenic European pear ( Pyrus communis L.) lines with reduced spermidine synthase ( SPDS) expression and spermidine (Spd) titers were developed using a construct containing an apple SPDS gene ( MdSPDS1) in antisense orientation. After exposure to either salt or cadmium stress, growth inhibition was more severe in the antisense lines than in the wild-type (WT). The antioxidant system, as shown by glutathione (GSH) content, activity of glutathione reductase (GR) and superoxide dismutase (SOD), and proline accumulation, was not effectively induced under stress in the antisense lines as compared with the WT. The reduction in antioxidant system function in the antisense lines was accompanied by a greater accumulation of malondialdehyde (MDA), an indicator of lipid peroxidation. Growth inhibition, Spd level, and parameters indicative of the antioxidant system were significantly ameliorated by exogenous Spd application. Under either salt or cadmium stress, GSH content, GR and SOD activity, and proline accumulation were positively correlated with Spd, putrescine (Put), and total polyamine titers. Conversely, MDA level showed a significantly negative correlation with these polyamines under both stress conditions. Thus, the responses to stress treatments were first identified in the SPDS antisense European pears, and the results provide further evidence for the important role of polyamines in both salt and cadmium stress tolerance, in which the polyamines act, at least in part, by influencing the antioxidant system.

Some radiobiological effects in higher plants growing on the territory of the East Ural Radioactive Trace

The spontaneous level of cytogenetic damage in three plant species (Achyrophorus maculatus (Scop.) L., Plantago lanceolata L., Plantago media L.) growing at the territory of East Ural radioactive trace was studied. The radiation resistance of plants from radioactive and control nonpolluted sites was determined. The effects of additional fractionated irradiation by different doses and the role of antioxidant systems in the formation of radioprotector effect were examined. It was shown that the level of mutation process in the plant populations growing at the radiation polluted sites is increased compared to the control populations from the pure territory. The additional acute gamma-irradiation of seeds collected from the polluted and pure territories showed the improved radiation resistance of the plants from the polluted territory. In the control population of A. maculatus in the versions with a one-hour interval between fractions, the radiation effect follows the additivity principle; in the same time, at a one-day interval between fractions, a highly significant radioprotective effect manifested most clearly in the experimental population is induced. For higher plants, the enhanced effectiveness of the functioning of antioxidant systems in plants growing at radiation polluted territories was first shown. Thus, the radioprotector mechanisms of low-dose chronic and preliminary irradiation are similar and one of these mechanisms is the activation of antioxidant systems in plants growing under conditions of chronic low-intensity irradiation for long periods of time.

Role of oxidative stress in various stages of psoriasis.

Psoriasis is a chronic inflammatory, proliferative skin disease characterized by pathological skin lesions due to various exogenous and endogenous factors. It is associated with a number of biochemical and immunological disturbances. Recently, it has been suggested that increased reactive oxygen species (ROS) production and compromised function of antioxidant system may be involved in the pathogenesis of this disease. In the present study, 90 psoriasis patients were selected. Disease severity was assessed by psoriasis area severity index score and grouped as mild, moderate and severe (each group consists of 30 subjects) and compared with 30 healthy controls. Serum levels of malondialdehyde, nitric oxide end products and the activities of antioxidant enzymes such as erythrocyte-superoxide dismutase, catalase and total antioxidant status were investigated in these groups/subjects. As compared to controls, we found severitywise significantly increased serum malondialdehyde, nitric oxide end products with decrease in erythrocyte-superoxide dismutase activity, catalase activity and total antioxidant status in patients with psoriasis suggesting worsening of the disease. It seems to be linked with the enhancement of Reactive Oxygen Species production and decreased antioxidant potential in psoriasis.

Effect ofMucuna prurienson oxidative stress mediated damage in aged rat sperm

Mucuna pruriens Linn., a leguminous plant, has been recognized as an aphrodisiac and spermatogenic agent. Protective efficacy of M. pruriens on reactive oxygen species (ROS)-induced pathophysiological alterations in structural and functional integrity of epididymal sperm in aged Wister albino rat was analysed. Animals were grouped as groups I, II, III and IV, i.e. young (control), aged, aged treated with ethanolic extract (200 mg/kg b.w.) of M. pruriens and young rats treated with M. pruriens, respectively. At the end of the experimental period, i.e. after 60 days animals were sacrificed, epididymal sperm were collected and subjected to count, viability, motility, morphology and morphometric analysis. Enzymatic and non-enzymatic antioxidants, ROS, lipid peroxidation (LPO), DNA damage, chromosomal integrity and mitochondrial membrane potential were estimated. Results obtained from the aged animals showed significant reduction in sperm count, viability and motility, increased morphological damage and an increase in the number of sperm with cytoplasmic remnant, and these alterations were significantly reversed in M. pruriens treated group. Significant increase in LPO, HO and H(2)O(2) production and significant decline in the levels of the enzymatic and non-enzymatic antioxidants were observed in the aged animals. Supplementation of M. pruriens significantly reduced ROS and LPO production and significant increase in both enzymatic and non-enzymatic antioxidant levels. There were significant DNA damage, loss of chromosomal integrity and increase in mitochondrial membrane permeability in aged rat sperm. This was significantly reduced in group III. Present observation indicates the antioxidant enhancing property, free radical quenching ability and spermatogenic efficacy of the M. pruriens. Collectively, sperm damage in ageing was significantly reduced by quenching ROS, improving antioxidant defence system and mitochondrial function.

The K/Na replacement and function of antioxidant defence system in sugar beet (Beta vulgaris L.) cultivars

Salinity is one of the major constrains restricting crop productivity. Sugar beet is one crop species grown mainly on salinity-affected soils. In a preliminary experiment in this work, the effect of different NaCl concentrations was studied on the growth of six cultivars of sugar beet (Beta vulgaris L.) in hydroponic medium. After selection of two contrasting cultivars, growth, sodium accumulation and distribution among leaf fractions as well as the functional significance of the antioxidant defence system under mild (50 mM) and severe salinity (200 mM) were investigated. NaCl treatment exerted either a stimulatory or an inhibitory effect on shoot growth, depending on concentration and cultivar. Higher growth improvement under mild salinity was observed in cultivar IC simultaneous with higher tolerance to severe saline treatment. Although two tested cultivars did not differ in Na concentration of leaves, its distribution among leaf fractions (apoplasmic fluid, cell wall, and cell sap) responded differentially to salinity treatment. Under mild salinity, proportional Na in cell sap of cultivar IC was greater than that of cultivar 7233, leading to greater replacement of K by Na in the former cultivar. In leaves of 7233, in contrast, proline was the major osmoticum. Activity of H2O2-scavenging enzymes (APX, CAT, and POD) was induced by salinity, keeping H2O2 concentration low under mild but not severe salinity. Shoot and root concentration of superoxide radicals was related to differential response of cultivars to salinity, i.e. IC was much more protected against superoxide radicals because of higher SOD activity than was 7233. Activity of nitrate reductase was reduced by both salinity levels and caused reduction of total free amino acids and protein concentrations. Results suggested that the main cause of cultivar difference is higher replacement of K by Na and allocation of more Na to the symplasm under mild salinity, and an indigenously higher protection against superoxide radicals under severe salinity.

Homeostasis of polyamines and antioxidant systems in roots and leaves of Plantago major under salt stress

Functioning of the antioxidant system in roots and leaves of Plantago major L. in water culture at the stage of 5–6 genuine leaves of the plants subjected to NaCl (100 mM) action for 96 h was investigated. This plant exhibited a pronounced organ specificity of antioxidant defense system functioning. The roots were characterized by high constitutive activities of superoxide dismutase and three forms of peroxidase, and a lower catalase activity. Constitutive level of polyamines in roots was higher than in leaves. In both leaves and roots during first 24 h, the polyamine content declined but spermidine remained to be a predominant polyamine. The analysis of differential expression of the genes encoding enzymes of polyamine biosynthesis demonstrated certain differences in these plant organs. The changes in expression of genes MET1, SPMS1, and SPMS2 were observed in roots, whereas in leaves expression of MET1, SAMDC1, SPDS1, and SPMS1 was altered. These changes are possibly one of the mechanisms responsible for the regulation of polyamine endogenous level under salinity. In contrast to leaves, in roots, the oxidative degradation of spermidine by polyamine oxidase can take part in the regulation of endogenous spermidine level. Taken together, these findings allowed us to conclude that, unlike leaves, the roots of P. major under salinity conditions possessed a higher activity of the antioxidant system protecting plants from injurious action of oxidative stress, thereby providing survival of this plant species under stress conditions.

Monosialoanglioside (GM1) prevents lead-induced neurotoxicity on long-term potentiation, SOD activity, MDA levels, and intracellular calcium levels of hippocampus in rats

Lead (Pb(2+)) is one of the most common neurotoxic metals present in our environment. Chronic or acute exposure to Pb(2+) causes impairment to the central nervous system (CNS). As one potent useful tool in the attempt to protect against impairment and promote functional recovery of the CNS, gangliosides are hopeful for recovering Pb(2+) neurotoxicity. The aim of this study is to investigate the effects of monosialoganglioside (GM1) on the Pb(2+)-induced impairments of synaptic plasticity, antioxidant system function, and intracellular calcium levels in the hippocampus of acute Pb(2+)-exposed rats. Our study showed that: (1) Acute Pb(2+) exposure impaired synaptic transmission and plasticity in the hippocampus and GM1 preconditioning rescued to some extent this impairment in urethane-anesthetized rats. (2) Superoxide dismutase activities and malondialdehyde levels were significantly increased in the acute Pb(2+)-exposed hippocampus which could be reduced by GM1 preconditioning. (3) Further, acute Pb(2+) exposure caused the internal free Ca(2+) fluctuation in the cultured hippocampal neurons and GM1 preconditioning could abate this fluctuation. Taken together, our results illustrated the possible mechanisms underlying the protective effects of GM1 against Pb(2+) neurotoxicity and might shed light on protection against Pb(2+) toxicity and its treatment.

Cognitive functions and the antioxidant system in phenylketonuric patients.

The authors studied the relationship between the antioxidant system and cognitive functions in a group of 36 early and continuously treated phenylketonuric (PKU) patients (mean age=9.7 years) and 29 controls. The authors measured antioxidant cofactors and free radical damage markers in plasma (selenium, retinol, tocopherol, coenzyme Q10, malondialdehide) and antioxidant enzymes in red blood cells (glutathione peroxidase, catalase, superoxide dismutase). The authors used neuropsychological tests to screen for several cognitive functions. PKU patients showed significantly lower values of selenium, coenzyme Q10, and catalase, and significantly higher levels of malondialdehide. PKU patients showed a significantly negative correlation between plasma selenium concentrations and several Conner's Continuous Performance Test measures (more omission errors, fluctuating attention and inconsistency of response times, and slowing reaction time as the test progressed). Selenium deficiency was thus associated with a worsened performance on the Conner's Continuous Performance Test among PKU patients. In conclusion, it is important not only to control blood Phe levels in PKU but also other nutritional components such as selenium. Selenium status seems to be associated with attention functions in these PKU patients.

Does antioxidant capacity of leaves play a role in growth response to selenium at different sulfur nutritional status?

There are evidences of beneficial effects of selenium (Se) on plant growth. In this work, using alfalfa (<i>Medicago sativa</i> L.) and two varieties of <i>Brassica oleracea</i> L. (cabbage and kohlrabi), the effect of Se addition (10 and 20μM) on growth and concentration of sulfur and Se was investigated in hydroponic experiments. In order to study the involvement of Se-mediated changes in the antioxidant capacity of plants in growth promotion by Se, the activity of antioxidant enzymes including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and glutathione reductase (GR) and the concentration of H<sub>2</sub>O<sub>2</sub> and glutathione were determined. It was demonstrated that sulfur sufficient cabbage and kohlrabi plants concomitant with growth stimulation in response to Se addition expressed a progressive oxidative stress as judged by a lower activity of antioxidant enzymes and accumulation of oxidants. Results imply that the function of antioxidant system of plants could not explain either the growth stimulatory effect of Se in cabbage and kohlrabi or different response of alfalfa plants to Se supplementation.

Anti-Oxidant NAC Prevents Hypersensitivity, Immunodeficiency and Lymphomagenesis in Atm−/− Mice.

Ataxia telangiectasia (A-T) is an autosomal recessive disorder characterized by immunodeficiency, progressive cerebellar ataxia, oculocutaneous telangiectasia, defective spermatogenesis, premature aging and high incidence of lymphoma. A-T is caused by the mutational inactivation of the “ataxia telangiectasia mutated” (ATM) gene. Ataxia telangiectasia mutated (ATM) plays a pivotal role in maintenance of genomic stability.Both A-T patients and Atm−/− mice show humeral and cellular immune defects, including thymic hypoplasia, low number of T-cells and deficiencies of Ig levels. It was originally believed that ATM was not essential for V(D)J recombination in T and B cells, a process which is mediated largely by the nonhomologous end-joining (NHEJ) pathway of DNA repair. However, several studies have revealed that ATM contributes to the prevention of interchromosomal translocations arising from aberrant V(D)J recombination. Thus, it remains unclear how ATM contributes to development of lymphocytes and prevention of lymphoma. It has been shown that deficient ATM function leads to abnormal reactive oxygen species (ROS) control. Several papers reported evidences for increased oxidative stress in tissues from A-T patients or Atm−/− mice, although the mechanism by which ATM regulates ROS level is unclear. Further, abnormalities in the levels and function of antioxidant systems in ATM-deficient cells have been reported. It has been assumed that increased ROS or abnormal response to ROS may contributes to neurodegenerative diseases and premature aging observed in A-T patients. We previously reported a critical role for ATM in stem cell self-renewal due to the effects of this kinase on the regulation of ROS during hematopoiesis. Treatment with the anti-oxidative agent N-acetyl-L-cystine (NAC) prevented the bone marrow failure observed in Atm−/− mice. It was reported that antioxidant prevented tumor development in p53−/− mice. Thus, appropriate ROS control is critical for clinical and cellular phenotypes of tumor-prone disorders.Here we show that a primary cause of immunodeficiency and lymphomagenesis in Atm−/− mice is the elevation of reactive oxygen species (ROS) present in these mutants. Reduction of ROS by NAC prevented the emergence of the senescent phenotype in mouse embryonic fibroblasts and hypersensitivity to total body irradiation in Atm−/− mice. The impairment of immunoglobulin class switch recombination (CSR) seen in Atm−/− mice was also mitigated by NAC, indicating that ROS elevation inhibits physiological DSBs rejoining in vivo. Significantly, in vivo treatment of Atm−/− mice with NAC restored normal T cell development, inhibited aberrant V(D)J recombination, and prevented thymic lymphomagenesis. We conclude that ATM-mediated ROS regulation is essential for the maintenance of genomic stability that prevents immunodeficiency and tumorigenesis. These findings may contribute to effective treatment of A-T patients for prevention of symptoms.

Effects of carbaryl on serum steroid hormone and the function of antioxidant system in female rats

To investigate the effects of carbaryl on serum steroid hormone and function of antioxidant system in female Sprague Dawley rats. Carbaryl was administrated to the adult female rats at doses of 0, 1.028, 5.140 and 25.704 mg x kg(-1) x d(-1) for 30 d. Vaginal smears of rats were taken to determine estrous cycle. Serum 17beta-estradiol (E(2)) and progesterone (P(4)) concentrations were measured by radioimmunoassay. The activities of superoxide dismutase (SOD) and glutathione-s-transferase (GST), and the levels of malondialdehyde (MDA) and glutathione (GSH) were measured by spectrophotometry. The number of estrous cycle in exposed groups were obviously lower than in control group (P < 0.05, P < 0.01). Body weight gain in high dose group (25.704 mg x kg(-1) x d(-1)) was significantly lower than that in control. Meanwhile, the organ coefficient of ovary and uterus declined in a dose-dependent manner. Serum E(2) level [(19.93 +/- 2.21) nmol/L] in 25.704 mg group was lower than in control group [(28.76 +/- 6.12) nmol/L, P < 0.05], and P(4) level (1.21 +/- 0.40) nmol/L in 1.028 mg group was higher than that in control group [(0.63 +/- 0.39) nmol/L, P < 0.05]. The activity of SOD first reduced then rose in ovary, and first rose then reduced in serum. The contents of MDA increased in ovary, while decreased in the serum. GSH contents and GST activity increased in ovary, while in serum GSH contents decreased and GST activity first increased then decreased. Carbaryl could disrupt estrous cycle and affect serum steroid hormone, and the function of antioxidant system in female SD rats.

Intervention of antioxidant system function of aged rats by giving fruit juices with different antioxidant capacities

To observe the effects of fruit juices with different antioxidant capacity on antioxidant system function of aged rats. Thirty Wistar rats were randomly divided into three groups: pomegranate juice and apple juice as two experimental groups, while distilled water as normal control group. They were administrated fruit juices or distilled water respectively by gavage daily for 4 weeks. At the end of experiment, the antioxidant system function was assessed. The aged rats in pomegranate juice group showed significantly higher serum antioxidant capacity (0.90 +/- 0.13) mmol/L than that in control group (0.79 +/- 0.10) mmol/L (P < 0.05). The concentrations of serum carbonyl and oxLDL were decreased significantly in pomegranate juice group as compared to the control group (P < 0.05). The percentage of injured blood lymphocyte DNA and the ratio of tail length/total length were declined significantly in pomegranate juice group (P < 0.05 and P < 0.01 respectively). The apple juice showed no effects except decreased ratio of tail length/total length of injured lymphocyte DNA. There were no changes in concentrations of serum vitamin C, vitamin E, urinary 8-OH-dG excretion and the activities of serum SOD, GSH-Px, CAT among three groups. The pomegranate juice should possess higher antioxidant capacity and might improve the antioxidant system function of aged rats, while the apple juice is relatively lower in antioxidant capacity and not very effective. The polyphenols in pomegranate juice might be the important functional components.

Effects of Ascorbic Acid on Cadmium-Induced Oxidative Stress and Performance of Broilers

The effects of cadmium on performance, antioxidant defense system, liver and kidney functions, and cadmium accumulation in selected tissues of broiler chickens were studied. Whether the possible adverse effects of cadmium would reverse with the antioxidant ascorbic acid was also investigated. Hence, 4 treatment groups (3 replicates of 10 chicks each) were designed in the study: control, ascorbic acid, cadmium, and cadmium plus ascorbic acid. Cadmium was given via the drinking water at a concentration of 25 mg/L for 6 wk. Ascorbic acid was added to the basal diet at 200 mg/kg either alone or with cadmium. Cadmium decreased the body weight (BW), body weight gain (BWG), and feed efficiency (FE) significantly at the end of the experiment, whereas its effect on feed consumption (FC) was not significant. Cadmium increased the plasma malondialdehyde (MDA) level as an indicator of lipid peroxidation and lowered the activity of blood superoxide dismutase (SOD). Liver function enzymes, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and gamma glutamyl transferase (GGT) activities were not changed by cadmium. Cadmium ingestion did not alter serum creatinine levels. Although the serum cadmium level was not elevated, cadmium mainly accumulated in the kidneys, liver, pancreas, and muscle. Ascorbic acid supplementation resulted in a reduction of MDA level previously increased by cadmium and a restoration in SOD activity. However, ascorbic acid did not ameliorate the growth inhibitory effect of cadmium nor did it prevent accumulation of cadmium in analyzed tissues. These data indicate that oxidative stress, induced by cadmium, plays a role in decreasing the performance of broilers and that dietary supplementation by ascorbic acid might be useful in reversing the lipid peroxidation induced by cadmium and partly alleviating the adverse effect of cadmium on performance of broilers.

Vitamin E-coated dialyzer and antioxidant defense parameters: Three-month study

Atherosclerotic cardiovascular disease is the most frequent cause of death in patients with end-stage renal disease who have undergone dialysis treatment. Oxidative stress, increased lipid peroxidation, and impaired function of antioxidant systems may contribute to the accelerated development of atherosclerosis in chronic renal failure patients during renal replacement therapy. The aim of this study was to investigate the influence of a vitamin E-coated dialyzer on antioxidant defense parameters in hemodialysis (HD) patients. In 14 HD patients, hemodialysis was performed using a vitamin E-coated dialyzer (Terumo CL-E15NL; Terumo Corporation, Tokyo, Japan) during a 3-month study. In these patients, erythrocyte (ER) antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR) and catalase (CAT), plasma total antioxidant capacity (TAC), RBC glutathione (GSH), plasma malondialdehyde (MDA), plasma, and RBC vitamin E were investigated. Each parameter was measured at the beginning of the study, after the 1st, 2nd, and 3rd month of the study, and 10 weeks after the interruption of the use of vitamin E-coated dialyzer. All HD patients were treated by erythropoietin (EPO) and received vitamin C 50 mg/d, pyridoxine 20 mg/d, and folic acid 5 mg/wk during the entire study. The 3-month treatment with the vitamin E-coated dialyzer led to a significant decrease of plasma MDA level (from 2.85 +/- 0.44 to 2.25 +/- 0.37 micromol/L) and to an increase of plasma TAC, RBC, GSH, and the vitamin E levels both in plasma (from 25.9 +/- 2.8 to 33.6 +/- 3.8 micromol/L) and in the RBCs (from 6.7 +/- 0.8 to 7.4 +/- 0.7 micromol/L) by 30% and 10.5%, respectively. Ten-week interruption of the use of the vitamin E-coated dialyzer led to near initial values of MDA (2.90 +/- 0.28 micromol/L), plasma (28.6 +/- 3.5 micromol/L), and RBC (6.9 +/- 0.7 micromol/L) vitamin E and of other investigated parameters. Statistical analysis of results was performed by conventional methods and analysis of variance. The findings of the current study confirm the beneficial effect of the vitamin E-coated dialyzer against oxidative stress in HD patients.

Evaluation of bee-collected pollen influence on lipid peroxidation, antioxidant system and liver function in old animals

Evaluation of bee-collected pollen influence on lipid peroxidation, antioxidant system and liver function in old animals

Redox analysis of human plasma allows separation of pro-oxidant events of aging from decline in antioxidant defenses.

Oxidative stress is a component of diseases and degenerative processes associated with aging. However, no means are available to assess causative oxidative events separately from decline in function of protective antioxidant systems. Previous studies show that ongoing oxidative processes maintain plasma cysteine/cystine redox at a value that is more oxidized than the antioxidant glutathione/glutathione disulfide (GSH/GSSG) system, suggesting that redox analysis of these plasma thiols could allow separate evaluation of an increase in oxidative events from a decline in antioxidant function. The present study uses measurement of cysteine/cystine and GSH/GSSG redox in plasma of 122 healthy individuals aged 19-85 years to determine whether thiol-disulfide redox changes occur with age. The results show a linear oxidation of cysteine/cystine redox state with age at a rate of 0.16 mV/year over the entire age span. In contrast, GSH/GSSG redox was not oxidized prior to 45 years and subsequently was oxidized at a nearly linear rate of 0.7 mV/year. These data suggest that there is a continuous, linear increase in oxidative events throughout adult life but that the capacity of the GSH antioxidant system is maintained until 45 years and then declines rapidly. The data further suggest that redox states of cysteine/cystine and GSH/GSSG provide an approach to clinically distinguish between increased causative oxidative events and decreased GSH antioxidant function. In principle, such analyses can be used to assess efficacy of intervention strategies against oxidative stress prior to or early after onset of clinical symptoms in aging and age-related disease.

Dissecting the superoxide dismutase-ascorbate-glutathione-pathway in chloroplasts by metabolic modeling. Computer simulations as a step towards flux analysis.

The present study introduces metabolic modeling as a new tool to analyze the network of redox reactions composing the superoxide dismutase-ascorbate (Asc)-glutathione (GSH) cycle. Based on previously determined concentrations of antioxidants and defense enzymes in chloroplasts, kinetic properties of antioxidative enzymes, and nonenzymatic rate constants of antioxidants with reactive oxygen, models were constructed to simulate oxidative stress and calculate changes in concentrations and fluxes of oxidants and antioxidants. Simulated oxidative stress in chloroplasts did not result in a significant accumulation of O2*- and H2O2 when the supply with reductant was sufficient. Model results suggest that the coupling between Asc- and GSH-related redox systems was weak because monodehydroascorbate radical reductase prevented dehydroascorbate (DHA) formation efficiently. DHA reductase activity was dispensable. Glutathione reductase was mainly required for the recycling of GSH oxidized in nonenzymatic reactions. In the absence of monodehydroascorbate radical reductase and DHA reductase, glutathione reductase and GSH were capable to maintain the Asc pool more than 99% reduced. This suggests that measured DHA/Asc ratios do not reflect a redox balance related to the Asc-GSH-cycle. Decreases in Asc peroxidase resulted in marked H2O2 accumulation without significant effects on the redox balance of Asc/DHA or GSH/GSSG. Simulated loss of SOD resulted in higher H2O2 production rates, thereby affecting all subsequent steps of the Asc-GSH-cycle. In conclusion, modeling approaches contribute to the theoretical understanding of the functioning of antioxidant systems by pointing out questions that need to be validated and provide additional information that is useful to develop breeding strategies for higher stress resistance in plants.

Collection of Arabidopsis thaliana mutants with altered sensitivity to oxidative stress inductors

Selective systems for screening Arabidopsis thaliana (L.) Heynh. mutants with altered sensitivity to the oxidative stress (OS) inductors norflurazon (NF), acifluorfen (AF), and plumbagin (PB) were developed and a collection of 28 mutants was obtained. Dwarf and necrotic forms predominated among the NF-tolerant mutants, while pigment mutants and those with changed root morphology prevailed among the AF-tolerant and PB-sensitive mutants, respectively. Genetic and biochemical analysis of certain mutants was performed; quantitative and qualitative changes in the content of superoxide dismutase and peroxidase isoforms have been revealed. These data, complemented by the data on the cross-tolerance (sensitivity) of the mutants to paraquat, indicate a correlation between tolerance to the OS inductors and the functions of antioxidant systems.