Induction Of Antioxidant Enzyme Activities Research Articles

Phenolics and Terpenoids Profiling in Diverse Loquat Fruit Varieties and Systematic Assessment of Their Mitigation of Alcohol-Induced Oxidative Stress.

To compare and investigate the phenolic compounds in the peel and flesh of loquat (Eriobotrya japonica) and evaluate their ability to protect against alcohol-induced liver oxidative stress, we employed a combination of ultra-performance liquid chromatography (UPLC) and high-resolution mass spectrometry (HRMS) to qualitatively and quantitatively analyze 22 phenolics and 2 terpenoid compounds in loquat peel and flesh extracts (extraction with 95% ethanol). Among these, six compounds were identified for the first time in loquat, revealing distinct distribution patterns based on variety and tissue. Various chemical models, such as DPPH, FRAP, ORAC, and ABTS, were used to assess free radical scavenging and metal ion reduction capabilities. The results indicate that peel extracts exhibited higher antioxidant capacity compared with flesh extracts. Using a normal mouse liver cell line, AML-12, we explored the protective effects of loquat extracts and individual compounds against ethanol-induced oxidative stress. The findings demonstrate the enhanced cell viability and the induction of antioxidant enzyme activity through the modulation of Nrf2 and Keap1 gene expression. In a C57/BL6 mouse model of alcohol-induced liver damage, loquat extract was found to alleviate liver injury induced by alcohol. The restoration of perturbed serum liver health indicators underscored the efficacy of loquat extract in reclaiming equilibrium. The culmination of these findings significantly bolsters the foundational knowledge necessary to explore the utilization of loquat fruit extract in the creation of health-focused products.

Overexpression of OsPIN9 Impairs Chilling Tolerance via Disturbing ROS Homeostasis in Rice.

The auxin efflux transporter PIN-FORMED (PIN) family is one of the major protein families that facilitates polar auxin transport in plants. Here, we report that overexpression of OsPIN9 leads to altered plant architecture and chilling tolerance in rice. The expression profile analysis indicated that OsPIN9 was gradually suppressed by chilling stress. The shoot height and adventitious root number of OsPIN9-overexpressing (OE) plants were significantly reduced at the seedling stage. The roots of OE plants were more tolerant to N-1-naphthylphthalamic acid (NPA) treatment than WT plants, indicating the disturbance of auxin homeostasis in OE lines. The chilling tolerance assay showed that the survival rate of OE plants was markedly lower than that of wild-type (WT) plants. Consistently, more dead cells, increased electrolyte leakage, and increased malondialdehyde (MDA) content were observed in OE plants compared to those in WT plants under chilling conditions. Notably, OE plants accumulated more hydrogen peroxide (H2O2) and less superoxide anion radicals (O2-) than WT plants under chilling conditions. In contrast, catalase (CAT) and superoxide dismutase (SOD) activities in OE lines decreased significantly compared to those in WT plants at the early chilling stage, implying that the impaired chilling tolerance of transgenic plants is probably attributed to the sharp induction of H2O2 and the delayed induction of antioxidant enzyme activities at this stage. In addition, several OsRboh genes, which play a crucial role in ROS production under abiotic stress, showed an obvious increase after chilling stress in OE plants compared to that in WT plants, which probably at least in part contributes to the production of ROS under chilling stress in OE plants. Together, our results reveal that OsPIN9 plays a vital role in regulating plant architecture and, more importantly, is involved in regulating rice chilling tolerance by influencing auxin and ROS homeostasis.

Treatment with omega-3 PUFAs does not increase the risk of CYP2E1-dependent oxidative stress and diabetic liver pathology.

An increase in CYP2E1 expression is a key factor in the development of diabetic oxidative liver damage. Long-term treatment with omega-3 PUFAs, which are CYP2E1 substrates, may affect CYP2E1 expression in the liver. In this work, we performed Western blot analysis, biochemical methods, and microscopic ultrastructural studies of the liver in a streptozotocin-induced rat model of type 1 diabetes to investigate whether long-term treatment with omega-3 PUFAs could induce CYP2E1-dependent oxidative stress and diabetic liver pathology. Significant hyperglycemia and lack of natural weight gain were observed in the diabetic rats compared to non-diabetic controls. A 2.5-fold increase in CYP2E1 expression (protein content and activity) was also observed in the diabetic rats. In addition, signs of oxidative stress were found in the liver of the diabetic rats. A significant increase in transaminases and GGT level in blood serum was also observed, which could indicate marked destruction of liver tissue. Diabetic dyslipidemia (increased triacylglycerol levels and decreased HDL-C levels) was found. Treatment of the diabetic animals with an omega-3-enriched pharmaceutical composition of PUFAs had no effect on CYP2E1 levels but contributed to a two-fold decrease in enzyme activity. The intensity of lipid peroxidation also remained close to the diabetic group. However, at the same time, antioxidant protection was provided by induction of antioxidant enzyme activity. Examination of the liver ultrastructure revealed no characteristic signs of diabetic pathology. However, omega-3 PUFAs did not normalize blood glucose levels and serum lipid profile. Thus, long-term treatment of diabetic rats with omega-3 PUFAs does not increase the risk of CYP2E1-dependent oxidative stress and development of liver pathology but prevents some diabetic ultrastructural damage to hepatocytes.

Negative Effect of Lambda-cyhalothrin (Insecticide) on Alazani River Fish, Luciobarbus Mursa

Pesticides are complex organic substances that are an important source of water pollution. Using pesticides is one of the important actions for harvest protection. This, however, does not negate the fact that its usage can result to negative consequences as well. The study of toxic action of lambda-cigalotrin (the piretroid of the insecticides which is included in icons, karate, commodore, samurai) on quantitative contents of fatty acids and structural lipids in muscle, gills, liver, and in the brain of fishes in river Alazani was carried out. Based on the actual material, one can conclude that intoxication of the fish tissues with lambda-cyhalotrin processes appear, which stimulates oxidation of free radicals of structural lipids. The peroxides of the initiators of free radicals are formed, which stimulate lipid per oxidation. Exposure to insecticides caused an induction of antioxidant enzyme activities indicating the activation of the insecticides detoxification pathways and the antioxidant defenses. The non-protein sulfhydryl groups increased to 1,75  0,109 compared to the control (1,04  0,123), while the total sulfhydryl groups statistically increased to 39,16  1,44 compared to the control (34,00  1,22 ).This indicates an increase in the concentration of protein and total sulfhydryl groups compared to controls. The study also identified that excess amounts of insecticides in the tissues disrupts the biochemical parameters. These changes may be potentially disruptive for the survivability of fish in natural resources. This fact should thus be taken into consideration when this insecticide is used for pest control in agriculture fields surrounding surface water and ground water resources.

Cold acclimation alleviates cold stress-induced PSII inhibition and oxidative damage in tobacco leaves

ABSTRACT This study aimed to explore how cold acclimation (CA) modulates cold stress in tobacco leaves and reveal the relationship between CA and cold stress resistance, and the mechanism of CA-induced plant resistance to cold stress. This study examined the effects of CA treatment (at 8–10℃ for 2 d) on the cold tolerance of tobacco leaves under 4°C cold stress treatment using seedlings without CA treatment as the control (NA). In both CA and NA leaves, cold stress treatment resulted in a decrease in maximum photochemical efficiency of PSII (F v /F m), increase in relative variable fluorescence (V J) at 2 ms on the standardized OJIP curve, inhibition of PSII activity, and impairment of electron transfer on the acceptor side. Besides increasing the malondialdehyde (MDA) content and electrolyte leakage rate, the cold stress exacerbated the degree of membrane peroxidation. The CA treatment also induced the accumulation of reactive oxygen species (ROS), including superoxide anion (O2·−) and H2O2, and increased the activities of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbic acid peroxidase (APX). The CA treatment also enhanced the accumulation of soluble sugar (SS) and soluble protein (SP), cyclic electron flow (CEF), and the proportion of regulatory energy dissipation Y(NPQ). Moreover, CA+ cold stress treatment significantly reduced CEF and Y(NPQ) in tobacco leaves than under NA+ cold stress treatment, thus significantly alleviating the degree of PSII photoinhibition. In conclusion, CA treatment significantly alleviated PSII photoinhibition and oxidative damage in tobacco leaves under cold stress treatment. Improvement in cold resistance of tobacco leaves is associated with the induction of antioxidant enzyme activity, accumulation of osmoregulation substances, and initiation of photoprotective mechanisms.

Biostimulant Capacity of an Enzymatic Extract From Rice Bran Against Ozone-Induced Damage in Capsicum annum.

Ozone is a destructive pollutant, damaging crops, and decreasing crop yield. Therefore, there is great interest in finding strategies to alleviate ozone-induced crop losses. In plants, ozone enters leaves through the stomata and is immediately degraded into reactive oxygen species (ROS), producing ROS stress in plants. ROS stress can be controlled by ROS-scavenging systems that include enzymatic or non-enzymatic mechanisms. Our research group has developed a product from rice bran, a by-product of rice milling which has bioactive molecules that act as an antioxidant compound. This product is a water-soluble rice bran enzymatic extract (RBEE) which preserves all the properties and improves the solubility of proteins and the antioxidant components of rice bran. In previous works, the beneficial properties of RBEE have been demonstrated in animals. However, to date, RBEE has not been used as a protective agent against oxidative damage in agricultural fields. The main goal of this study was to investigate the ability of RBEE to be used as a biostimulant by preventing oxidative damage in plants, after ozone exposure. To perform this investigation, pepper plants (Capsicum annuum) exposed to ozone were treated with RBEE. RBEE protected the ozone-induced damage, as revealed by net photosynthetic rate and the content of photosynthetic pigments. RBEE also decreased the induction of antioxidant enzyme activities in leaves (catalase, superoxide dismutase, and ascorbate peroxidase) due to ozone exposure. ROS generation is a common consequence of diverse cellular traumas that also activate the mitogen-activated protein kinase (MAPK) cascade. Thus, it is known that the ozone damages are triggered by the MAPK cascade. To examine the involvement of the MAPK cascade in the ozone damage CaMPK6-1, CaMPK6-2, and CaMKK5 genes were analyzed by qRT-PCR. The results showed the involvement of the MAPK pathway in both, not only in ozone damage but especially in its protection by RBEE. Taken together, these results support that RBEE protects plants against ozone exposure and its use as a new biostimulant could be proposed.

Toxicities of three metal oxide nanoparticles to a marine microalga: Impacts on the motility and potential affecting mechanisms

With the fast growth of the production and application of engineered nanomaterials (ENMs), nanoparticles (NPs) that escape into the environment have drawn increasing attention due to their ecotoxicological impacts. Motile microalgae are a type of primary producer in most ecosystems; however, the impacts of NPs on the motility of microalgae have not been studied yet. So the toxic impacts of three common metal oxide NPs (nTiO2, nZnO, and nFe2O3) on swimming speed and locomotion mode of a marine microalgae, Platymonas subcordiformis, were investigated in this study. Our results demonstrated that both the velocity and linearity (LIN) of swimming were significantly decreased after the exposure of P. subcordiformis to the tested NPs. In addition, the obtained data indicate that NPs may suppress the motility of P. subcordiformis by constraining the energy available for swimming, as indicated by the significantly lower amounts of intracellular ATP and photosynthetic pigments and the lower activities of enzymes catalyzing glycolysis. Incubation of P. subcordiformis with the tested NPs generally resulted in the overproduction of reactive oxygen species (ROS), aggravation of lipid peroxidation, and induction of antioxidant enzyme activities, suggesting that imposing oxidative stress, which may impair the structural basis for swimming (i.e. the membrane of flagella), could be another reason for the observed motility suppression. Moreover, NP exposure led to significant reductions in the cell viability of P. subcordiformis, which may be due to the disruption of the energy supply (i.e., photosynthesis) and ROS-induced cellular damage. Our results indicate that waterborne NPs may pose a great threat to motile microalgae and subsequently to the health and stability of the marine ecosystem.

Induction of cell division and antioxidative enzyme activity of Matricaria chamomilla L. cell line under clino-rotation

This study represents an optimized protocol for cell line culture of Matricaria chamomilla and the impact of clino-rotation on cell division, cell growth, and antioxidant enzyme activities for the first time. The cell suspension was transferred in the solid MS medium supplied with 2, 4-D, and KIN. Then the calli produced from a cell line were selected for callus subculture and clino-rotation treatment for 7 days by a 2D-clinostat. A significant rise of fresh and dry weights, cell division, total soluble sugar, reducing sugar, and starch contents were detected under clino-rotation. Protein content approximately unchanged in microgravity-treated calli. Antioxidant enzymes activities, such as peroxidase, catalase (CAT), and superoxide dismutase were elevated in calli exposed to microgravity. CAT activity showed a more than three-fold increase than that of control. According to native polyacrylamide gel electrophoresis, all the antioxidant enzymes isoforms were stronger in clino-rotated calli than that of the untreated control. Microgravity also stimulated H2O2 production and markedly adjusted lipid peroxidation in calli exposed to clino-rotation. These findings suggest that clino-rotation with stimulation of carbohydrate accumulation and antioxidant enzymes mitigates oxidative stress and improves growth and cell division. The isolation of M. chamomilla cell line with high growth was conducted to study the impact of clino-rotation on some cellular and antioxidative enzyme responses. Clino-rotation stimulated the cell division and growth by induction of antioxidant enzyme activities.

Revegetation intervention of drought-prone coal-mined spoils using Caragana korshinskii under variable water and nitrogen-phosphorus resources

Coal-mine spoils are typically drought-prone and deficient in essential nutrients thus creating conditions, which significantly limit plant growth and development. Here, we searched for suitable combinations of key resources [water (W) and fertilizers (nitrogen, N and phosphorus, P)] to improve physiological and biochemical adaptations of Caragana korshinskii to coal-mined spoils. We observed that under low W and N-P resource availability, C. korshinskii displayed poor growth performance in coal-degraded spoils. Negative growth of C. korshinskii was associated with reduced photosynthetic rate, decreased water status and increased contents of reactive oxygen species (ROS) and malondialdehyde. Low resource availability to C. korshinskii resulted in enhanced levels of compatible solutes, including proline and soluble sugars that contributed to osmotic adjustment, and also increased activities of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase, which ultimately conferred enhanced oxidative stress protection. Moderate-to-high W and N-P doses greatly enhanced C. korshinskii performance in coal-spoils by improving photosynthesis traits, water status and growth-related attributes. Increasing supply of W and N-P also helped C. korshinskii to reduce oxidative stress, as evidenced by low accumulation of ROS and malondialdehyde, and lower induction of antioxidant enzyme activities. The addition of N and P also improved drought resistance of C. korshinskii. Overall, we found that optimum growth of C. korshinskii in coal-mined spoils was achieved under W additions corresponding to 68% of field capacity (1.85 mmd1), N and P at 52.0 and 37.0 mg kg1 soil, respectively. These findings suggest that under appropriate W, N and P doses, C. korshinskii has greater potential to grow and persist in coal-mined spoils and could thus be used for revegetation interventions in drought-prone areas in north-western China, and perhaps across other coal-degraded areas worldwide.

Chitosan nanoparticles from Artemia salina inhibit progression of hepatocellular carcinoma in vitro and in vivo.

This study was conducted to evaluate the effect of chitosan nanoparticles (CNPs) isolated from Artemia salina against hepatocellular carcinoma (HCC) both in vitro (HepG2) and in vivo (diethylnitrosamine-induced HCC in rats) and to investigate the involved underlying mechanisms. Administration of CNPs decreased HCC progression as evidenced by (1) induced HepG2 cell death as detected by MTT assay; (2) induced necrosis as indicated by acridine orange/propidium iodide (AO/PI) red staining, annexin V/7-AAD positive staining (detected by flow cytometry), and upregulated expression of necrosis markers (PARP1 and its downstream target, RIP1 genes), but no effect on apoptosis as revealed by insignificant changes in caspase 3 activity and mRNA levels of Bax and AIF; (3) increased intracellular ROS and decreased mitochondrial membrane potential in HepG2; (4) decreased liver relative weight, serum levels of liver enzymes (ALT, AST, and ALP), total bilirubin, and cancer markers (AFP and GGT), number and area of GST-P positive tumor nodules; and (5) reduced oxidative stress (decrease in MDA levels) and increased activities of SOD, CAT, and GPx enzymes in rat liver. The preventive (pre-treatment) effect of CNPs was better than the therapeutic (post-treatment) effect. Collectively, administration of CNPs inhibited HCC progression in vitro and in vivo, possibly through induction of necrosis, rather than apoptosis, and induction of antioxidant enzyme activities in vivo, but with stimulation of ROS production in vitro. Thus, CNPs could be used as a promise agent for treating HCC after application of further confirmatory clinical trials.

Antioxidative systems, metal ion homeostasis and cadmium distribution in Iris lactea exposed to cadmium stress

Iris lactea is a perennial halophyte and is tolerant to Cd. However, the mechanisms underlying this Cd tolerance are still poorly understood. In this study, morphological, physiological and biochemical responses of I. lactea to a 21 d exposure to different concentrations of Cd (0–150mgL−1) were investigated. I. lactea plants showed no toxicity symptoms except for a small reduction in growth at 100 and 150mgL−1 Cd, along with the enhancement of H2O2 and MDA content in comparison to the control. The activities of SOD and POD were significantly enhanced and Ca accumulated with increasing Cd concentrations. Moreover, most Cd was retained in roots and only a small amount was transported to the shoots with increasing external Cd concentrations. Cd content had a negative correlation with content of K, Fe, Zn, and Mn and a positive correlation with Mg content in shoots and roots, which had no influence on these contents of mineral nutrients in shoots and chlorophyll levels with the increase of Cd concentrations. The Cd translocation factors were always less than 1 and bioaccumulation factors ranged from 3.43 to 15.6 across all treatments, suggesting that I. lactea might be effectively used in phytostabilization of Cd contaminated soils. Overall, the findings suggest that I. lactea could reduce photoinhibition and oxidative damage and maintain metal ion homeostasis in plant tissue by limiting translocation of Cd from roots to shoots and enhancing induction of antioxidant enzyme activities, thereby improving its Cd tolerance.

Molecular cloning and functional analysis of a novel phytoglobin gene from the alpine plant Stipa purpurea

Background: Stipa purpurea, the dominant species of the alpine steppe in the Tibetan Plateau, survives well under various abiotic stresses including drought, hypoxia and chilling.Aims: To understand the molecular mechanism by which alpine plants including S. purpurea adapt to the abiotic environmental factors of the Tibetan Plateau.Methods: We cloned the coding domain sequence of one Phytogb gene from S. purpurea using the rapid amplification of cDNA ends method and analysed its function by heterologous expression in Arabidopsis.Results: The Phytogb gene, which we named StipurPhytogb1, included 474 nucleotides and encoded a protein of 157 amino acids. Functional analyses showed that StipurPhytogb1 could improve the resistance of transgenic Arabidopsis to drought and hypoxia caused by waterlogging. Further analyses suggested that StipurPhytogb1 improved the above resistance by inhibiting nitric oxide accumulation and mediating the induction of antioxidant enzyme activities to scavenge reactive oxygen species.Conclusion: These findings indicate that StipurPhytogb1 may play an essential role in the adaptation of S. purpurea to drought and the hypoxic environment of the Tibetan Plateau and has potential as a candidate gene for genetic transformation to improve plant stress tolerance.

Effect of inoculation of symbiotic fungi on the growth and antioxidant enzymes’ activities in the presence of Fusarium subglutinans f. sp. ananas in pineapple plantlets

The inoculation with symbiotic fungi, Arbuscular mycorrhizal fungi (AMF) and/or Piriformospora indica on the growth, nutrient absorption, and induction of antioxidant enzyme activities in plantlets of pineapple ‘Imperial’ (fusariosis-resistant) and ‘Perola’ (fusariosis-susceptible) in the presence of Fusarium subglutinans f. sp. ananas was investigated. The experiment was comprised by two cultivars, with or without fungal inoculation (Claroideoglomus etunicatum, Rhizophagus clarus, and P. indica, a mixture of all the fungi, and the control—absence of fungal inoculation), with or without applying Fusarium conidia, and with four replicates. In both cultivars, nutrient absorption was higher in the AMF plantlets compared to those inoculated with P. indica or the control ones, although it was more efficient in ‘Imperial’ than in ‘Perola’. Inoculation with AMF and/or P. indica as well as the pathogen influenced differently the activities of superoxide dismutase, catalase, glutathione reductase, peroxidase, and polyphenol oxidase, in the shoots or roots of pineapple plantlets in both cultivars. Inoculated plantlets with mixture of all the fungi also exhibited a better growth and nutrient absorption, and generally, the ‘Imperial’ responded better than ‘Perola’. In addition, these plantlets developed better than the control even in the presence of pathogen, indicating that inoculation with AMF and/or P. indica may contribute to the production of more resistant propagative material. Increased antioxidant enzyme activity is a potential strategy for managing this plant for explore biological control as an alternative to reduce environmental and health impacts by reducing the use of fungicides.

Protective Effect of Pelargonium graveolens Essential Oil Against Alloxan-Induced Diabetes and Oxidative Stress in Rats

Oxidative stress occurs in diabetic patients and experimental models of diabetes. The antioxidant property of Pelargonium graveolens essential oil (PGEO) might have a beneficial effect in ameliorating the disease. In this context, the aim of the present study was to investigate the effects of PGEO on oxidative stress in alloxan-induced diabetes in rats. The antidiabetic and antioxidant activities were evaluated after sub-acute intraperitoneal injection of male rats to 42.5 mg/kg b.w. essential oil for 21 days. In results, we found that PGEO significantly protected against the increase of blood glucose induced by alloxan treatment. In addition, we showed that sub-acute essential oil treatment induced a decrease of lipoperoxydation, as well as, the induction of antioxidant enzyme activities. The use of GC-MS technique revealed the identification of many compounds in PGEO with (R)-citronellol (31.61%) as the main compound. The protective effect of PGEO is mainly attributed to antioxidant property.

Effects of nitrogen dioxide and its acid mist on reactive oxygen species production and antioxidant enzyme activity in Arabidopsis plants

Nitrogen dioxide (NO2) is one of the most common and harmful air pollutants. To analyze the response of plants to NO2 stress, we investigated the morphological change, reactive oxygen species (ROS) production and antioxidant enzyme activity in Arabidopsis thaliana (Col-0) exposed to 1.7, 4, 8.5, and 18.8mg/m3 NO2. The results indicate that NO2 exposure affected plant growth and chlorophyll (Chl) content, and increased oxygen free radical (O2−) production rate in Arabidopsis shoots. Furthermore, NO2 elevated the levels of lipid peroxidation and protein oxidation, accompanied by the induction of antioxidant enzyme activities and change of ascorbate (AsA) and glutathione (GSH) contents. Following this, we mimicked nitric acid mist under experimental conditions, and confirmed the antioxidant mechanism of the plant to the stress. Our results imply that NO2 and its acid mist caused pollution risk to plant systems. During the process, increased ROS acted as a signal to induce a defense response, and antioxidant status played an important role in plant protection against NO2/nitric acid mist-caused oxidative damage.

EFFECT OF PUMPKIN ROOTSTOCK ON ANTIOXIDANT ENZYME ACTIVITIES AND PHOTOSYNTHETIC FLUORESCENCE CHARACTERISTICS OF CUCUMBER UNDER CA(NO3)2 STRESS

The aim of this study was to determine whether the documented induction of cucumber (Cucumis sativus L.) seedling tolerance to Ca(NO3)2 stress by grafting onto pumpkin (Cucurbita maxima A— C. moschata) is associated with the protection of antioxidant enzymes and photosynthetic fluorescence characteristics. Greenhouse experiments were carried out to determine antioxidant enzyme activities, gas exchange, and photosystem II (PSII) efficiency of self-grafted and pumpkin-grafted (rootstock-grafted) ‘Jinyou No. 3’ cucumber plants. Plants were grown hydroponically and supplied with two nutrient solutions: a non-salinized control and a salinized solution containing 80 mM Ca(NO3)2. Under Ca(NO3)2 treatment, antioxidant enzyme activities first increased and then decreased, with maximal levels observed upon 12 h of treatment. The induction of antioxidant enzyme activity by Ca(NO3)2 stress was more significant when cucumber plants were grafted onto pumpkin rootstock. Relative to the control, reductions in net photosynthetic rate, intercellular CO2 concentration, and stomatal conductance under 12 h of Ca(NO3)2 treatment were significantly lower in rootstock-grafted plants (8.2, 19.9, and 35.6%, respectively) than in self-grafted ones (18.5, 39.4, and 90.9%, respectively). In rootstock-grafted plants subjected to Ca(NO3)2 stress, relative reductions in the ratio of maximal to variable fluorescence, relative quantum efficiency of PSII photochemistry and the photochemical quenching coefficient were also significantly lower than in self-grafted plants; enhancement of non-photochemical quenching was significantly higher, however, suggesting that rootstock-grafted plants had higher potential to dissipate excess excitation energy and to reduce the probability of photodamage to PSII. Taken together, the use of salt-tolerant pumpkin rootstock can improve cucumber antioxidant defense and photosynthetic capacity under Ca(NO3)2 stress and consequently lead to enhanced plant performance.

Cigarette smoke–induced induction of antioxidant enzyme activities in airway leukocytes is absent in active smokers with COPD

BackgroundOxidative injury to the airway has been proposed as an important underlying mechanism in the pathogenesis of chronic obstructive pulmonary disease (COPD). As the extent of oxidant-mediated damage is dependent on the endogenous antioxidant defences within the airways, we examined whether COPD was associated with deficiencies in the antioxidant network within the respiratory tract lining fluids (RTLFs) and resident airway leukocytes. We hypothesised that COPD would be associated with both basal depression of antioxidant defences and impaired adaptive antioxidant responses to cigarette smoke.MethodsLow molecular weight and enzymatic antioxidants together with metal-handling proteins were quantified in bronchoalveolar lavage fluid and airway leukocytes, derived from current (n=9) and ex-smoking COPD patients (n=15), as well as from smokers with normal lung function (n=16) and healthy never smokers (n=13).ResultsCurrent cigarette smoking was associated with an increase in ascorbate and glutathione within peripheral RTLFs in both smokers with normal lung function compared with healthy never smokers and in COPD smokers compared with COPD ex-smokers. In contrast, intra-cellular antioxidant enzyme activities (glutathione peroxidase, glutathione reductase, and catalase) were only up-regulated in smokers with normal lung function compared with healthy never smokers and not in actively smoking COPD patients relative to COPD ex-smokers.ConclusionsWe found no evidence of impaired basal antioxidant defences, within either the RTLFs or airway leukocytes in stable ex-smoking COPD patients compared with healthy never smoking controls. Current cigarette smoking induced an up-regulation of low molecular weight antioxidants in the RTLFs of both control subjects with normal lung function and patients with COPD. Importantly, the present data demonstrated a cigarette smoke–induced increase in intra-cellular antioxidant enzyme activities only within the smokers with normal lung function, implying that patients with COPD who continue to smoke will experience enhanced oxidative stress, prompting disease progression.

Physiological integration enhanced the tolerance of Cynodon dactylon to flooding.

Many flooding-tolerant species are clonal plants; however, the effects of physiological integration on plant responses to flooding have received limited attention. We hypothesise that flooding can trigger changes in metabolism of carbohydrates and ROS (reactive oxygen species) in clonal plants, and that physiological integration can ameliorate the adverse effects of stress, subsequently restoring the growth of flooded ramets. In the present study, we conducted a factorial experiment combining flooding to apical ramets and stolon severing (preventing physiological integration) between apical and basal ramets of Cynodon dactylon, which is a stoloniferous perennial grass with considerable flooding tolerance. Flooding-induced responses including decreased root biomass, accumulation of soluble sugar and starch, as well as increased activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in apical ramets. Physiological integration relieved growth inhibition, carbohydrate accumulation and induction of antioxidant enzyme activity in stressed ramets, as expected, without any observable cost in unstressed ramets. We speculate that relief of flooding stress in clonal plants may rely on oxidising power and electron acceptors transferred between ramets through physiological integration.

Detoxifying effect of fermented black ginseng on H2O2-induced oxidative stress in HepG2 cells.

Fermented black ginseng (FBG) is prepared by repeated steaming and drying processes with fresh ginseng followed by fermentation with Saccharomyces cerevisiae. It has recently been shown to have several bioactivities. FBG contains crude saponin (1,440 µg/ml), ginsenoside Rg2 (2.86 µg/ml), ginsenoside Rg3 (24.52 µg/ml), ginsenoside Rh1 (12.64 µg/ml), ginsenoside Rh2 (0.63 µg/ml) and ginsenoside Rf (1.32 µg/ml). The present study investigated the antioxidant defense properties of FBG against hydrogen peroxide (H2O2)-mediated oxidative stress in HepG2 human hepatocellular carcinoma cells. The increased production of reactive oxygen species (ROS) induced by H2O2 was attenuated in a dose-dependent manner when the cells were pre-treated with FBG (10-50 µg/ml). FBG induced both the expression and activity of antioxidant enzymes, such as superoxide dismutase, catalase and glutathione peroxidase in the H2O2-treated HepG2 cells. The inhibitory effects of FBG on the phosphorylation of upstream mitogen-activated protein kinases (MAPKs), such as c-Jun N-terminal kinase, extracellular signal-regulated kinase and p38 were also observed. Overall, our results demonstrate that FBG protects HepG2 cells from oxidative stress through the induction of antioxidant enzyme activity and the inhibition of MAPK pathways.

Reactive oxygen species and ascorbate–glutathione interplay in signaling and stress responses in Sesamum orientale L. against Alternaria sesami (Kawamura) Mohanty and Behera

Sesamum orientale wild and cultivar Thilarani exposed to Alternaria sesami infection triggered the signal cascade H2O2 content that was positively correlated with lipid peroxidation. The data were also supported by H2O2 localization as observed by scanning electron microscopy. Parallely, infection altered chloroplasts marginally and mitochondria effectively in susceptible cultivar than wild sesame. Deformities in the structure of these organelles were accompanied by changes in antioxidant machinery. H2O2 can be effectively detoxified via the ascorbate–glutathione cycle. Increases in ascorbate peroxidase, and glutathione reductase activities concomitant with ascorbate (AsA) and glutathione interplay, as well as AsA regeneration ability, function to keep the balance of cellular H2O2 under pathogenicity. Dehydroascorbate reductase and monodehydroascorbate reductase are responsible for AsA regeneration. Oxidative damage in Thilarani cultivar compared to wild sesame is attributed by a lower induction of the ascorbate–glutathione cycle as an antioxidant defense system and was not sufficient to protect mitochondria but prevent ultrastructural damage of chloroplasts. Overall, the availability of antioxidants and the induction of antioxidant enzyme activities for detoxifying reactive oxygen species (ROS) are regulated effectively in wild sesame against A. sesami induced oxidative stress. The experiments using ROS scavengers demonstrate that the antioxidant defense system is modulated by O2− or H2O2 signals.