Molecular Mechanisms of Neuroprotection after the Intermittent Exposures of Hypercapnic Hypoxia

The review introduces the stages of formation and experimental confirmation of the hypothesis regarding the mutual potentiation of neuroprotective effects of hypoxia and hypercapnia during their combined influence (hypercapnic hypoxia). The main focus is on the mechanisms and signaling pathways involved in the formation of ischemic tolerance in the brain during intermittent hypercapnic hypoxia. Importantly, the combined effect of hypoxia and hypercapnia exerts a more pronounced neuroprotective effect compared to their separate application. Some signaling systems are associated with the predominance of the hypoxic stimulus (HIF-1α, A1 receptors), while others (NF-κB, antioxidant activity, inhibition of apoptosis, maintenance of selective blood-brain barrier permeability) are mainly modulated by hypercapnia. Most of the molecular and cellular mechanisms involved in the formation of brain tolerance to ischemia are due to the contribution of both excess carbon dioxide and oxygen deficiency (ATP-dependent potassium channels, chaperones, endoplasmic reticulum stress, mitochondrial metabolism reprogramming). Overall, experimental studies indicate the dominance of hypercapnia in the neuroprotective effect of its combined action with hypoxia. Recent clinical studies have demonstrated the effectiveness of hypercapnic-hypoxic training in the treatment of childhood cerebral palsy and diabetic polyneuropathy in children. Combining hypercapnic hypoxia with pharmacological modulators of neuro/cardio/cytoprotection signaling pathways is likely to be promising for translating experimental research into clinical medicine.

Mitigation of salt stress in lettuce by a biostimulant that protects the root absorption zone and improves biochemical responses

Horticultural crops constantly face abiotic stress factors such as salinity, which have intensified in recent years due to accelerated climate change, significantly affecting their yields and profitability. Under these conditions, it has become necessary to implement effective and sustainable solutions to guarantee agricultural productivity and food security. The influence of BALOX®, a biostimulant of plant origin, was tested on the responses to salinity of Lactuca sativa L. var. longifolia plants exposed to salt concentrations up to 150 mM NaCl, evaluating different biometric and biochemical properties after 25 days of treatment. Control plants were cultivated under the same conditions but without the biostimulant treatment. An in situ analysis of root characteristics using a non-destructive, real-time method was also performed. The salt stress treatments inhibited plant growth, reduced chlorophyll and carotenoid contents, and increased the concentrations of Na+ and Cl- in roots and leaves while reducing those of Ca2+. BALOX® application had a positive effect because it stimulated plant growth and the level of Ca2+ and photosynthetic pigments. In addition, it reduced the content of Na+ and Cl- in the presence and the absence of salt. The biostimulant also reduced the salt-induced accumulation of stress biomarkers, such as proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2). Therefore, BALOX® appears to significantly reduce osmotic, ionic and oxidative stress levels in salt-treated plants. Furthermore, the analysis of the salt treatments' and the biostimulant's direct effects on roots indicated that BALOX®'s primary mechanism of action probably involves improving plant nutrition, even under severe salt stress conditions, by protecting and stimulating the root absorption zone.

Polymer Gel Substrate: Synthesis and Application in the Intensive Light Artificial Culture of Agricultural Plants

This work is devoted to the description of the synthesis of hydrogels in the process of cryotropic gel formation based on copolymerization of synthesized potassium 3-sulfopropyl methacrylate and 2-hydroxyethyl methacrylate (SPMA-co-HEMA) and assessing the potential possibility of their use as substrates for growing plants in intensive light culture in a greenhouse. Gel substrates based on the SPMA-co-HEMA were created in two compositions, differing from each other in the presence of macro- and microelements, and their effects were studied on the plants' physiological state (content of chlorophylls a and b, activity of catalase and peroxidase enzymes, intensity of lipid peroxidation, elemental compositions) at the vegetative period of their development and on the plants' growth, productivity and quality of plant production at the final stages of development. Experiments were carried out under controlled microclimate conditions. Modern and standard generally accepted methods of gels were employed (ATR-FTIR and 13C NMR spectral studies, scanning electron microscopy, measurement of specific surface area and pore volume), as well as the methods of the physiological and chemical analysis of plants. The study demonstrated the swelling ability of the created gel substrates. Hydrogels' structure, their specific surface area, porosity, and pore volume were investigated. Using the example of representatives of leaf, fruit and root vegetable crops, the high biological activity of gel substrates was revealed throughout the vegetation period. Species specificity in the reaction of plants to the presence of gel substrates in the root-inhabited environment was revealed. Lettuce, tomato and cucumber plants were more responsive to the effect of the gel substrate, and radish plants were less responsive. At the same time, more pronounced positive changes in plant growth, quality and productivity were observed in cucumber and lettuce in the variant of gel substrates with macro- and microelements and in tomato plants in both variants of gel substrates. Further research into the mechanisms of the influence of gel substrates on plants, as well as the synthesis of new gel substrates with more pronounced properties to sorb and retain moisture is promising.

[Changes in the Activity of Antioxidant Systems of Escherichia coli under Phosphate Starvation]

Changes in the activity of antioxidant systems in Escherichia coli during phosphate starvation have been studied. It is shown that starvation was accompanied by a decrease in the intensity of respiration, an increase in the rate of superoxide production, and a decrease in the level of ATP. Simultaneously, there was a decrease in H2O2 in the medium and a significant increase in the expression of the katG and katE genes which encode the HPI and HPII catalases, respectively. At the same time, there was no drop in the membrane potential, which may indicate the retention of normal membrane activity in starving cells. It has been shown for the first time that the transition of E. coli to phosphate starvation is accompanied by significant changes in the status of glutathione. The most important of these are associated with a decrease in the level of reduced glutathione in the medium (GSHout) and with a simultaneous increase in its content in the cytoplasm (GSHin), as well as a shift in the GSHin to oxidized glutathione form (GSSGin) ratio towards reductive values, and GSHout/GSSGout towards oxidative values. Among the mutants used in the work, the gor trxB double mutant, which is deficient in the synthesis of glutathione reductase and thioredoxin reductase, showed the most pronounced distinctive features. Compared to the parental strain, this mutant showed a multiple higher expression of katG::lacZ, the highest level of oxidized intra- and extracellular glutathione, and, accordingly, the lowest GSH/GSSG ratio in both compartments. In general, the data we obtained indicate that during phosphate starvation the interaction of the glutathione redox-system and regulons that control protection against reactive oxygen species creates conditions that allow maintaining the concentration of ROS below the toxic level. As a result, phosphate-starved E. coli cells can maintain high viability for a long period of time, which allows them to quickly resume growth after the addition of phosphate.

1-Methylcyclopropene Alleviates Postharvest Chilling Injury of Snap Beans by Enhancing Antioxidant Defense System

Research background

Chilling injury is a major disorder affecting the quality of tropical and subtropical vegetables during low temperature storage. Snap bean (Phaseolus vulgaris L.) is sensitive to chilling injury. The main purpose of the present study is to investigate the alleviating effects of 1-methylcyclopropene (1-MCP) on chilling injury of snap bean. In addition, the related mechanisms were also detected from the perspective of the changes of antioxidant defense system.

Experimental approach

Snap beans were exposed to different volume fractions of 1-MCP. After 24 h of treatment, snap beans were stored at 4 °C for up to 14 days. Chilling injury index, electrolyte leakage, titratable acidity and total soluble solids were determined. Contents of chlorophyll, ascorbic acid and malondialdehyde were assessed. The total antioxidant capacity, Fe(II) ion chelating capacity, scavenging capacities on free radicals and activities of antioxidant enzymes were detected. Total phenol content and activities of related metabolic enzymes were also determined.

Results and conclusions

1-MCP treatment reduced chilling injury index, electrolyte leakage rate and malondialdehyde content of snap beans. The amounts of total soluble solids, titratable acid, ascorbic acid and total chlorophyll in 1-MCP-treated snap beans were significantly higher than those of control. The snap beans treated with 1-MCP showed stronger total antioxidant capacity and metal chelating activity. The 1-MCP treatment enhanced scavenging effects of snap beans on superoxide, hydroxyl and 1,1-diphenyl-2-trinitrophenylhydrazine radicals. The activities of peroxidase, ascorbate peroxidase, superoxide dismutase and catalase in 1-MCP-treated group were higher than of control. The treatment also enhanced the accumulation of phenolic compounds in snap beans by regulating the activities of phenol-metabolizing enzymes such as shikimate dehydrogenase, phenylalanine ammonia lyase enzyme, cinnamic acid 4-hydroxylase and polyphenol oxidase. In conclusion, with the mechanism that involves the activation of enzymatic and non-enzymatic antioxidant systems, 1-MCP has the ability to avoid chilling injury of snap bean.

Novelty and scientific contribution

This study gives insights into whether 1-MCP can regulate postharvest cold resistance in vegetables by enhancing the enzymatic antioxidant system and inducing the accumulation of non-enzymatic antioxidants. Considering the results, 1-MCP treatment could be an effective method to alleviate postharvest chilling injury of snap beans during low temperature storage.

Targeting reactive oxygen species and fat acid oxidation for the modulation of tumor-associated macrophages: a narrative review

Tumor-associated macrophages (TAMs) are significant immunocytes infiltrating the tumor microenvironment(TME). Recent research has shown that TAMs exhibit diversity in terms of their phenotype, function, time, and spatial distribution, which allows for further classification of TAM subtypes. The metabolic efficiency of fatty acid oxidation (FAO) varies among TAM subtypes. FAO is closely linked to the production of reactive oxygen species (ROS), which play a role in processes such as oxidative stress. Current evidence demonstrates that FAO and ROS can influence TAMs' recruitment, polarization, and phagocytosis ability either individually or in combination, thereby impacting tumor progression. But the specific mechanisms associated with these relationships still require further investigation. We will review the current status of research on the relationship between TAMs and tumor development from three aspects: ROS and TAMs, FAO and TAMs, and the interconnectedness of FAO, ROS, and TAMs.

How Can Biological and Chemical Silver Nanoparticles Positively Impact Physio-Chemical and Chloroplast Ultrastructural Characteristics of Vicia faba Seedlings?

Through interactions with plant cells, silver nanoparticles (AgNPs) with both biological and chemical origins can stimulate physiological and metabolic processes in plants. To ensure their safe application in the food chain, it is necessary to investigate their effects on plant systems. Therefore, the effects of chemical AgNPs (chem-AgNPs) and biologically synthesized AgNPs (bio-AgNPs) at different levels (i.e., 0, 10, and 50 ppm) on physiological and biochemical traits {i.e., root and shoot growth traits, photosynthetic pigments (Chl a, Chl b, carotenoids, and total pigments), soluble sugars, total carbohydrates, starch, H₂O₂, and antioxidant enzyme activities} of Vicia faba L. seedlings were investigated. AgNPs were biosynthesized from silver nitrate (AgNO₃) by a green synthesis approach using Jatropha curcas seed extract. The synthesized AgNPs were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), zeta potential, Fourier-transform infrared spectra (FT-IR), and X-ray diffraction (XRD). The results showed that bio-AgNPs at 10 ppm resulted in the highest growth, physiological, and biological traits of faba bean seedlings in comparison with those obtained from both AgNO₃ and chem-AgNPs treatments. On the other hand, all AgNPs treatments adversely affected the chloroplast ultrastructure, however, fewer negative effects were obtained with the application of 10 ppm bio-AgNPs. In addition, the roots and shoots of seedlings contained the lowest Ag content under different treatments at 10 ppm AgNPs in comparison to the highest level of AgNPs (50 ppm), which indicates that additional studies should be incorporated to ensure safe use of lower concentrations of bio-AgNPs in seed priming. In conclusion, the application of biogenic nanoparticles at 10 ppm can be recommended to enhance plant growth and the productivity of strategic crops.

Potentiation of Cisplatin Cytotoxicity in Resistant Ovarian Cancer SKOV3/Cisplatin Cells by Quercetin Pre-Treatment

Previously, we demonstrated that the overexpression of antioxidant enzymes (SOD-1, SOD-2, Gpx-1, CAT, and HO-1), transcription factor NFE2L2, and the signaling pathway (PI3K/Akt/mTOR) contribute to the cisplatin resistance of SKOV-3/CDDP ovarian cells, and treatment with quercetin (QU) alone has been shown to inhibit the expression of these genes. The aim of this study was to expand the previous data by examining the efficiency of reversing cisplatin resistance and investigating the underlying mechanism of pre-treatment with QU followed by cisplatin in the same ovarian cancer cells. The pre-incubation of SKOV-3/CDDP cells with quercetin at an optimum dose prior to treatment with cisplatin exhibited a significant cytotoxic effect. Furthermore, a long incubation with only QU for 48 h caused cell cycle arrest at the G1/S phase, while a QU pre-treatment induced sub-G1 phase cell accumulation (apoptosis) in a time-dependent manner. An in-depth study of the mechanism of the actions revealed that QU pre-treatment acted as a pro-oxidant that induced ROS production by inhibiting the thioredoxin antioxidant system Trx/TrxR. Moreover, QU pre-treatment showed activation of the mitochondrial apoptotic pathway (cleaved caspases 9, 7, and 3 and cleaved PARP) through downregulation of the signaling pathway (mTOR/STAT3) in SKOV-3/CDDP cells. This study provides further new data for the mechanism by which the QU pre-treatment re-sensitizes SKOV-3/CDDP cells to cisplatin.

Untargeted metabonomic analysis of non-alcoholic fatty liver disease with iron overload in rats via UPLC/MS

BACKGROUND/AIMS

In recent years, many metabolites specific to nonalcoholic fatty liver disease (NAFLD) have been identified thanks to the application of metabolomics techniques. This study aimed to investigate the candidate targets and potential molecular pathways involved in NAFLD in the presence of iron overload.

METHODS

Male Sprague Dawley rats were fed with control or high-fat diet with or without excess iron. After 8,16,20 weeks of treatment, urine samples of rats were collected for metabolomics analysis using ultra-performance liquid chromatography/mass spectrometry (UPLC-MS). Blood and liver samples were also collected.

RESULTS

High-fat, high-iron diet resulted in increased triglyceride accumulation and increased oxidative damage. A total of 13 metabolites and four potential pathways were identified. Compared to the control group, the intensities of adenine, cAMP, hippuric acid, kynurenic acid, xanthurenic acid, uric acid, and citric acid were significantly lower (P < 0.05) and the concentration of other metabolites was significantly higher in the high-fat diet group. In the high-fat, high-iron group, the differences in the intensities of the above metabolites were amplified.

CONCLUSION

Our findings suggest that NAFLD rats have impaired antioxidant system and liver function, lipid disorders, abnormal energy, and glucose metabolism, and that iron overload may further exacerbate these disorders.

Use of a Biostimulant to Mitigate the Effects of Excess Salinity in Soil and Irrigation Water in Tomato Plants

Global warming is linked to progressive soil salinisation, which reduces crop yields, especially in irrigated farmland on arid and semiarid regions. Therefore, it is necessary to apply sustainable and effective solutions that contribute to enhanced crop salt tolerance. In the present study, we tested the effects of a commercial biostimulant (BALOX^®) containing glycine betaine (GB) and polyphenols on the activation of salinity defense mechanisms in tomato. The evaluation of different biometric parameters and the quantification of biochemical markers related to particular stress responses (osmolytes, cations, anions, oxidative stress indicators, and antioxidant enzymes and compounds) was carried out at two phenological stages (vegetative growth and the beginning of reproductive development) and under different salinity conditions (saline and non-saline soil, and irrigation water), using two formulations (different GB concentrations) and two doses of the biostimulant. Once the experiments were completed, the statistical analysis revealed that both formulations and doses of the biostimulant produced very similar effects. The application of BALOX^® improved plant growth and photosynthesis and assisted osmotic adjustment in root and leaf cells. The biostimulant effects are mediated by the control of ion transport, reducing the uptake of toxic Na⁺ and Cl^- ions and favoring the accumulation of beneficial K⁺ and Ca²⁺ cations, and a significant increase in leaf sugar and GB contents. BALOX^® significantly reduced salt-induced oxidative stress and its harmful effects, as evidenced by a decrease in the concentration of oxidative stress biomarkers, such as malondialdehyde and oxygen peroxide, which was accompanied by the reduction of proline and antioxidant compound contents and the specific activity of antioxidant enzymes with respect to the non-treated plants.

Mitochondrial Peroxiredoxin 3 Is Rapidly Oxidized and Hyperoxidized by Fatty Acid Hydroperoxides

Human peroxiredoxin 3 (HsPrx3) is a thiol-based peroxidase responsible for the reduction of most hydrogen peroxide and peroxynitrite formed in mitochondria. Mitochondrial disfunction can lead to membrane lipoperoxidation, resulting in the formation of lipid-bound fatty acid hydroperoxides (_LFA-OOHs) which can be released to become free fatty acid hydroperoxides (_fFA-OOHs). Herein, we report that HsPrx3 is oxidized and hyperoxidized by _fFA-OOHs including those derived from arachidonic acid and eicosapentaenoic acid peroxidation at position 15 with remarkably high rate constants of oxidation (>3.5 × 10⁷ M^-1s^-1) and hyperoxidation (~2 × 10⁷ M^-1s^-1). The endoperoxide-hydroperoxide PGG₂, an intermediate in prostanoid synthesis, oxidized HsPrx3 with a similar rate constant, but was less effective in causing hyperoxidation. Biophysical methodologies suggest that HsPrx3 can bind hydrophobic structures. Indeed, molecular dynamic simulations allowed the identification of a hydrophobic patch near the enzyme active site that can allocate the hydroperoxide group of _fFA-OOHs in close proximity to the thiolate in the peroxidatic cysteine. Simulations performed using available and herein reported kinetic data indicate that HsPrx3 should be considered a main target for mitochondrial _fFA-OOHs. Finally, kinetic simulation analysis support that mitochondrial _fFA-OOHs formation fluxes in the range of nM/s are expected to contribute to HsPrx3 hyperoxidation, a modification that has been detected in vivo under physiological and pathological conditions.

Leucine Contributes to Copper Stress Tolerance in Peach (Prunus persica) Seedlings by Enhancing Photosynthesis and the Antioxidant Defense System

Heavy metal contamination has a severe impact on ecological health and plant growth and is becoming increasingly serious globally. Copper (Cu) is a heavy metal that is essential for the growth and development of plants, including peach (Prunus persica L. Batsch); however, an excess is toxic. In plants, amino acids are involved in responses to abiotic and biotic stresses, such as water deficit, extreme temperatures, high salinity, and heavy metal stress. However, the role of leucine in the regulation of heavy metal stress is currently unclear. Therefore, we investigated the effects of exogenous leucine on the growth of peach seedlings under Cu stress. Exogenous leucine improved the leaf ultrastructure and ionic balance and increased the chlorophyll content, the net photosynthetic rate, and the maximum photochemical efficiency. Furthermore, it attenuated Cu-stress-induced oxidative damage via a decrease in reactive oxygen species (ROS) and the regulation of the antioxidant and osmotic systems. These effects, in turn, ameliorated the reductions in cell viability, cellular activity, and biomass under Cu stress. Moreover, exogenous leucine increased the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamic acid synthetase (GOGAT) and thus improved the nitrogen metabolism efficiency of plants. In conclusion, leucine significantly improved the photosynthetic performance and antioxidant capacity, reduced Cu accumulation, and promoted nitrogen metabolism, which in turn improved the resistance of peach seedlings to Cu stress.

S-Denitrosylation: A Crosstalk between Glutathione and Redoxin Systems

S-nitrosylation of proteins occurs as a consequence of the derivatization of cysteine thiols with nitric oxide (NO) and is often associated with diseases and protein malfunction. Aberrant S-nitrosylation, in addition to other genetic and epigenetic factors, has gained rapid importance as a prime cause of various metabolic, respiratory, and cardiac disorders, with a major emphasis on cancer and neurodegeneration. The S-nitrosoproteome, a term used to collectively refer to the diverse and dynamic repertoire of S-nitrosylated proteins, is relatively less explored in the field of redox biochemistry, in contrast to other covalently modified versions of the same set of proteins. Advancing research is gradually unveiling the enormous clinical importance of S-nitrosylation in the etiology of diseases and is opening up new avenues of prompt diagnosis that harness this phenomenon. Ever since the discovery of the two robust and highly conserved S-nitrosoglutathione reductase and thioredoxin systems as candidate denitrosylases, years of rampant speculation centered around the identification of specific substrates and other candidate denitrosylases, subcellular localization of both substrates and denitrosylases, the position of susceptible thiols, mechanisms of S-denitrosylation under basal and stimulus-dependent conditions, impact on protein conformation and function, and extrapolating these findings towards the understanding of diseases, aging and the development of novel therapeutic strategies. However, newer insights in the ever-expanding field of redox biology reveal distinct gaps in exploring the crucial crosstalk between the redoxins/major denitrosylase systems. Clarifying the importance of the functional overlap of the glutaredoxin, glutathione, and thioredoxin systems and examining their complementary functions as denitrosylases and antioxidant enzymatic defense systems are essential prerequisites for devising a rationale that could aid in predicting the extent of cell survival under high oxidative/nitrosative stress while taking into account the existence of the alternative and compensatory regulatory mechanisms. This review thus attempts to highlight major gaps in our understanding of the robust cellular redox regulation system, which is upheld by the concerted efforts of various denitrosylases and antioxidants.

64Cu-ATSM Predicts Efficacy of Carbon Ion Radiotherapy Associated with Cellular Antioxidant Capacity

Simple Summary

Carbon ion radiotherapy is an emerging cancer treatment modality that has a greater therapeutic window than conventional photon radiotherapy. To maximize the efficacy of this extremely scarce medical resource, it is important to identify predictive biomarkers of higher carbon ion relative biological effectiveness (RBE) over photons. Here we show that the carbon ion RBE in human cancer cells correlates with the cellular uptake of ⁶⁴Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (⁶⁴Cu-ATSM), a potential radioligand that reflects an over-reduced intracellular environment. High RBE/⁶⁴Cu-ATSM cells show greater steady-state levels of antioxidant proteins and increased capacity to scavenge reactive oxygen species in response to X-rays than low RBE/⁶⁴Cu-ATSM counterparts. These data suggest that the cellular antioxidant activity is a possible determinant of carbon ion RBE predictable by ⁶⁴Cu-ATSM uptake.

Abstract

Carbon ion radiotherapy is an emerging cancer treatment modality that has a greater therapeutic window than conventional photon radiotherapy. To maximize the efficacy of this extremely scarce medical resource, it is important to identify predictive biomarkers of higher carbon ion relative biological effectiveness (RBE) over photons. We addressed this issue by focusing on cellular antioxidant capacity and investigated ⁶⁴Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (⁶⁴Cu-ATSM), a potential radioligand that reflects an over-reduced intracellular environment. We found that the carbon ion RBE correlated with ⁶⁴Cu-ATSM uptake both in vitro and in vivo. High RBE/⁶⁴Cu-ATSM cells showed greater steady-state levels of antioxidant proteins and increased capacity to scavenge reactive oxygen species in response to X-rays than low RBE/⁶⁴Cu-ATSM counterparts; this upregulation of antioxidant systems was associated with downregulation of TCA cycle intermediates. Furthermore, inhibition of nuclear factor erythroid 2-related factor 2 (Nrf2) sensitized high RBE/⁶⁴Cu-ATSM cells to X-rays, thereby reducing RBE values to levels comparable to those in low RBE/⁶⁴Cu-ATSM cells. These data suggest that the cellular activity of Nrf2-driven antioxidant systems is a possible determinant of carbon ion RBE predictable by ⁶⁴Cu-ATSM uptake. These new findings highlight the potential clinical utility of ⁶⁴Cu-ATSM imaging to identify high RBE tumors that will benefit from carbon ion radiotherapy.

Resveratrol shortens the chronological lifespan of Saccharomyces cerevisiae by a pro-oxidant mechanism

The antioxidant phenotype caused by resveratrol has been recognized as a key piece in the health benefits exerted by this phytochemical in diseases related to aging. It has recently been proposed that a mitochondrial pro-oxidant mechanism could be the cause of resveratrol antioxidant properties. In this regard, the hypothesis that resveratrol impedes electron transport to complex III of the electron transport chain as its main target suggests that resveratrol could increase reactive oxygen species (ROS) generation through reverse electron transport or by the semiquinones formation. This idea also explains that cells respond to resveratrol oxidative damage, inducing their antioxidant systems. Moreover, resveratrol pro-oxidant properties could accelerate the aging process, according to the free radical theory of aging, which postulates that organism's age due to the accumulation of the harmful effects of ROS in cells. Nonetheless, there is no evidence linking the chronological lifespan (CLS) shorten occasioned by resveratrol with a pro-oxidant mechanism. Hence, this study aimed to evaluate whether resveratrol shortens the CLS of Saccharomyces cerevisiae due to a pro-oxidant activity. Herein, we provide evidence that supplementation with 100 μM of resveratrol at 5% glucose: (1) shortened the CLS of ctt1Δ and yap1Δ strains; (2) decreased ROS levels and increased the catalase activity in WT strain; (3) maintained unaffected the ROS levels and did not change the catalase activity in ctt1Δ strain; and (4) lessened the exponential growth of ctt1Δ strain, which was restored with the adding of reduced glutathione. These results indicate that resveratrol decreases CLS by a pro-oxidant mechanism.

The Arbuscular Mycorrhizal Fungus Glomus viscosum Improves the Tolerance to Verticillium Wilt in Artichoke by Modulating the Antioxidant Defense Systems

Verticillium wilt, caused by the fungal pathogen Verticillium dahliae, is the most severe disease that threatens artichoke (Cynara scolymus L.) plants. Arbuscular mycorrhizal fungi (AMF) may represent a useful biological control strategy against this pathogen attack, replacing chemical compounds that, up to now, have been not very effective. In this study, we evaluated the effect of the AMF Glomus viscosum Nicolson in enhancing the plant tolerance towards the pathogen V. dahliae. The role of the ascorbate-glutathione (ASC-GSH) cycle and other antioxidant systems involved in the complex network of the pathogen-fungi-plant interaction have been investigated. The results obtained showed that the AMF G. viscosum is able to enhance the defense antioxidant systems in artichoke plants affected by V. dahliae, alleviating the oxidative stress symptoms. AMF-inoculated plants exhibited significant increases in ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and superoxide dismutase (SOD) activities, a higher content of ascorbate (ASC) and glutathione (GSH), and a decrease in the levels of lipid peroxidation and hydrogen peroxide (H₂O₂). Hence, G. viscosum may represent an effective strategy for mitigating V. dahliae pathogenicity in artichokes, enhancing the plant defense systems, and improving the nutritional values and benefit to human health.

Nitrosative Redox Homeostasis and Antioxidant Response Defense in Disused Vastus lateralis Muscle in Long-Term Bedrest (Toulouse Cocktail Study)

Increased oxidative stress by reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a major determinant of disuse-induced muscle atrophy. Muscle biopsies (thigh vastus lateralis, VL) obtained from healthy male subjects enrolled in the Toulouse Cocktail bedrest (BR) study were used to assess efficacy of an antioxidant cocktail (polyphenols, omega-3, vitamin E, and selenium) to counteract the increased redox homeostasis and enhance the antioxidant defense response by using label-free LC–MS/MS and NITRO-DIGE (nitrosated proteins), qPCR, and laser confocal microscopy. Label-free LC–MS/MS indicated that treatment prevented the redox homeostasis dysregulation and promoted structural remodeling (TPM3, MYH7, MYBPC, MYH1, MYL1, HRC, and LUM), increment of RyR1, myogenesis (CSRP3), and skeletal muscle development (MUSTN1, LMNA, AHNAK). These changes were absent in the Placebo group. Glycolysis, tricarboxylic acid cycle (TCA), oxidative phosphorylation, fatty acid beta-oxidation, and mitochondrial transmembrane transport were normalized in treated subjects. Proteins involved in protein folding were also normalized, whereas protein entailed in ion homeostasis decreased. NITRO-DIGE analysis showed significant protein nitrosylation changes for CAT, CA3, SDHA, and VDAC2 in Treatment vs. Placebo. Similarly, the nuclear factor erythroid 2-related factor 2 (Nrf-2) antioxidant response element (Nrf-2 ARE) signaling pathway showed an enhanced response in the Treatment group. Increased nitrosative redox homeostasis and decreased antioxidant defense response were found in post-BR control (Placebo, n = 10) vs. the antioxidant cocktail treated group (Treatment, n = 10). Taken together, increased nitrosative redox homeostasis and muscle deterioration during BR-driven physical inactivity were prevented, whereas decreased antioxidant nitrosative stress defense response was attenuated by Treatment suggesting positive effects of the nutritional intervention protocol in bedrest.

Oxidative Stress and ROS-Mediated Signaling in Leukemia: Novel Promising Perspectives to Eradicate Chemoresistant Cells in Myeloid Leukemia

Myeloid leukemic cells are intrinsically under oxidative stress due to impaired reactive oxygen species (ROS) homeostasis, a common signature of several hematological malignancies. The present review focuses on the molecular mechanisms of aberrant ROS production in myeloid leukemia cells as well as on the redox-dependent signaling pathways involved in the leukemogenic process. Finally, the relevance of new chemotherapy options that specifically exert their pharmacological activity by altering the cellular redox imbalance will be discussed as an effective strategy to eradicate chemoresistant cells.

The homeostatic role of hydrogen peroxide, superoxide anion and nitric oxide in the vasculature

Reactive oxygen and nitrogen species are produced in a wide range of physiological reactions that, at low concentrations, play essential roles in living organisms. There is a delicate equilibrium between formation and degradation of these mediators in a healthy vascular system, which contributes to maintaining these species under non-pathological levels to preserve normal vascular functions. Antioxidants scavenge reactive oxygen and nitrogen species to prevent or reduce damage caused by excessive oxidation. However, an excessive reductive environment induced by exogenous antioxidants may disrupt redox balance and lead to vascular pathology. This review summarizes the main aspects of free radical biochemistry (formation, sources and elimination) and the crucial actions of some of the most biologically relevant and well-characterized reactive oxygen and nitrogen species (hydrogen peroxide, superoxide anion and nitric oxide) in the physiological regulation of vascular function, structure and angiogenesis. Furthermore, current preclinical and clinical evidence is discussed on how excessive removal of these crucial responses by exogenous antioxidants (vitamins and related compounds, polyphenols) may perturb vascular homeostasis. The aim of this review is to provide information of the crucial physiological roles of oxidation in the endothelium, vascular smooth muscle cells and perivascular adipose tissue for developing safer and more effective vascular interventions with antioxidants.

An unorthodox pathophysiology of severe cases of COVID-19 the weak heme hypothesis

Important amount of severe cases is the main concern in COVID-19 pandemic. It could be the running cause of the burn out of the health system in many countries. The aim of this paper is to suggest a pathophysiologic hypothesis to explain the main characteristics of severe cases of COVID-19 and its underlying conditions. In fact, the clinical and biological picture of severe cases of COVID-19 can easily be explained by free heme toxicity exceeding the endogenous antioxidant systems. Severe cases of COVID-19 are comparable to acute porphyria. On the other hand, the geographical distribution of severe cases of COVID-19 is directly associated to how fresh or polluted the air is. Finally, the relatively low rate of severe cases of COVID-19 could be explained by the presence of an unstable hemoglobin variant highly sensitive to the intrinsic conditions resulting from the acute pneumonia secondary to SARS-CoV2 infection. The combination of air pollution and free heme toxicity, resulting from the interaction between an unstable hemoglobin variant and SARS-CoV2 infection, seems to be the best scheme to explain clinical and biological manifestations in severe COVID-19. The arguments to support this hypothesis are detailed. We also propose some strategies to verify the concordance of our hypothesis with the reality and the implications it could have, if verified, either for scientists and decision makers.

Reactive Oxygen Species and Antioxidant Defense in Plants under Abiotic Stress: Revisiting the Crucial Role of a Universal Defense Regulator

Global climate change and associated adverse abiotic stress conditions, such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants and employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and nonenzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.

Thioredoxin, Glutathione and Related Molecules in Tumors of the Nervous System

BACKGROUND

Central Nervous System (CNS) tumors have a poor survival prognosis due to their invasive and heterogeneous nature, in addition to the resistance to multiple treatments.

OBJECTIVE

In this paper, the main aspects of brain tumor biology and pathogenesis are reviewed both for primary tumors of the brain, (i.e., gliomas) and for metastasis from other malignant tumors, namely lung cancer, breast cancer and malignant melanoma which account for a high percentage of overall malignant brain tumors. We review the role of antioxidant systems, namely the thioredoxin and glutathione systems, in the genesis and/or progression of brain tumors.

METHODS

Although overexpression of Thioredoxin Reductase (TrxR) and Thioredoxin (Trx) is often linked to increased malignancy rate of brain tumors, and higher expression of Glutathione (GSH) and Glutathione S-Transferases (GST) are associated to resistance to therapy, several knowledge gaps still exist regarding for example, the role of Peroxiredoxins (Prx), and Glutaredoxins (Grx).

CONCLUSION

Due to their central role in redox homeostasis and ROS scavenging, redox systems are potential targets for new antitumorals and examples of innovative therapeutics aiming at improving success rates in brain tumor treatment are discussed.

Effect of ethanol fumigation on pericarp browning associated with phenol metabolism, storage quality, and antioxidant systems of wampee fruit during cold storage

Wampee fruit is a popular fruit cultivar in South-East Asia due to its high levels of nutrients and antioxidants; however, pericarp browning leads to a short storage life with great economic loss during years. The purpose of this work was to determine whether postharvest ethanol fumigation affected pericarp browning development of wampee fruit during 12 days of storage at 8 ± 0.5°C, and if so, how it is related to phenol metabolism and how it affects quality attributes and antioxidant systems during storage. After fruits were fumigated with 100, 300, 500, and 800 μl/L for 5 hr at 22 ± 0.5°C, ethanol significantly reduced the development of pericarp browning by increasing total phenolics (TP) content and decreasing the activity of polyphenol oxidase (PPO), especially in 500 μl/L ethanol treatment. Additionally, ethanol delayed the losses in fruit firmness (FF), soluble solid content (SSC), and titratable acidity (TA), retarded weight loss and accumulation of malondialdehyde (MDA) content and maintained relatively high contents of ascorbic acid (AsA), total flavonoids (TF), and total antioxidant capacity (TAC) and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). In conclusion, results demonstrated that postharvest ethanol fumigation in wampee fruit has ability to reduce pericarp browning development by regulating phenol metabolism and enhancing antioxidant systems.

Ascorbic Acid Induces the Increase of Secondary Metabolites, Antioxidant Activity, Growth, and Productivity of the Common Bean under Water Stress Conditions

One of the most vital environmental factors that restricts plant production in arid and semi-arid environments is the lack of fresh water and drought stress. Common bean (Phaseolus vulgaris L.) productivity is severely limited by abiotic stress, especially climate-related constraints. Therefore, a field experiment in split-plot design was carried out to examine the potential function of ascorbic acid (AsA) in mitigating the adverse effects of water stress on common bean. The experiment included two irrigation regimes (100% or 50% of crop evapotranspiration) and three AsA doses (0, 200, or 400 mg L^-1 AsA). The results revealed that water stress reduced common bean photosynthetic pigments (chlorophyll and carotenoids), carbonic anhydrase activity, antioxidant activities (2,2-diphenyl-1-picrylhydrazyl free radical activity scavenging activity and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation assay), growth and seed yield, while increased enzymatic antioxidants (peroxidase), secondary metabolites (phenolic, flavonoids, and tannins), malondialdehyde (MDA), and crop water productivity. In contrast, the AsA foliar spray enhanced all studied traits and the enhancement was gradual with the increasing AsA dose. The linear regression model predicted that when the AsA dose increase by 1.0 mg L^-1, the seed yield is expected to increase by 0.06 g m^-2. Enhanced water stress tolerance through adequate ascorbic acid application is a promising strategy to increase the tolerance and productivity of common bean under water stress. Moreover, the response of common bean to water deficit appears to be dependent on AsA dose.

Why Does the Halophyte Mesembryanthemum crystallinum Better Tolerate Ni Toxicity than Brassica juncea: Implication of Antioxidant Defense Systems

The implication of enzymatic and non-enzymatic antioxidative systems in response to Ni was evaluated in the halophyte Mesembryanthemum crystallinum in comparison with the metal tolerant glycophyte species Brassica juncea. Seedlings of both species were hydroponically subjected during 21 days to 0, 25, 50, and 100 µM NiCl2. Growth parameters showed that the halophyte M. crystallinum was more tolerant to Ni than B. juncea. Malondialdehyde (MDA) content increased to a higher extent in B. juncea than in M. crystallinum. Antioxidant enzymesactivities were differently affected by Ni in both species. Nickel increased shoot superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities in B. juncea, whereas these activities were reduced in M. crystallinum when exposed to metal stress. The root SOD, APX and guaiacol peroxidase (GPX) activities increased upon Ni treatments for both species. The content of non-enzymatic antioxidative molecules such as glutathione, non-protein thiols and proline increased in Ni-treated plants, except for GSH content in the shoot of B. juncea. Based on the oxidative balance, our findings confirm the higher tolerance of the halophyte M. crystallinum to Ni-induced oxidative stress comparatively to B. juncea. We suggest that M. crystallinum is able to overcome the produced ROS using the non-enzymatic system, while Ni-induced oxidative stress was more acute in B. juncea, leading this species to mainly use the enzymatic system to protect against reactive oxygen species.

Chronic Tobacco Exposure by Smoking Develops Insulin Resistance

BACKGROUND AND OBJECTIVES

The present review critically discusses the high occurrence rate, insulin resistance and type-2 diabetes in tobacco exposed individuals. Tobacco extracts and smoke contain a large number of toxic materials and a significant number of those are metabolic disintegrators.

DISCUSSION

Glucose and lipid homeostasis is severely impaired by this compound. Tobacco exposure contributes to adverse effects by impairing the physical, biochemical and molecular mechanisms in the tissues. The immunological components are damaged by tobacco with high production of proinflammatory cytokines (IL-6, TNF-∞) and augmentation of inflammatory responses. These events result in damages to cytoskeletal structures of different tissues. Degradation of matrix structure (by activation of different types of MMPs) results in the permanent damages to the tissues and their metabolic functions. Cellular antioxidant defense system mostly cannot or hardly nullify CS-induced ROS production that activates polymorphonuclear neutrophils (PMNs), which are a major source of cytokines and chemokines (TNFα, IL6, IL8, INFγ). Additive effects of these immediately promote the low energy-metabolism as well as inflammation. Oxidative stress, mitochondrial dysfunction, and inflammation contribute to the direct nicotine toxicity via nAChRs in diabetes. The investigator identified that skeletal muscle insulin-resistance occurs in smokers due to phosphorylation of insulin receptor substrate1 (IRS1) at Ser-636 position.

CONCLUSION

Tobacco exposure initiates free radical related immunological impairment, DNA damage, and inflammation. So, the present analysis is of importance to figure out the mechanistic layout of tobacco-induced tissue damage and its possible therapeutic interventions.

The Delicate Equilibrium between Oxidants and Antioxidants in Brain Glioma

Gliomas are the most frequent brain tumors in the adult population and unfortunately the adjuvant therapies are not effective. Brain tumorigenesis has been related both to the increased levels of free radicals as inductors of severe damages in healthy cells, but also with the reduced response of endogenous enzyme and non-enzymatic antioxidant defenses. In turn, both processes induce the change to malignant cells. In this review, we analyzed the role of the imbalance between free radicals production and antioxidant mechanism in the development and progression of gliomas but also the influence of redox status on the two major distinctive forms of programmed cell death related to cancer: apoptosis and autophagy. These data may be the reference to the development of new pharmacological options based on redox microenvironment for glioma treatment.

Melatonin: A Small Molecule but Important for Salt Stress Tolerance in Plants

Salt stress is one of the most serious limiting factors in worldwide agricultural production, resulting in huge annual yield loss. Since 1995, melatonin (N-acetyl-5-methoxytryptamine)—an ancient multi-functional molecule in eukaryotes and prokaryotes—has been extensively validated as a regulator of plant growth and development, as well as various stress responses, especially its crucial role in plant salt tolerance. Salt stress and exogenous melatonin lead to an increase in endogenous melatonin levels, partly via the phyto-melatonin receptor CAND2/PMTR1. Melatonin plays important roles, as a free radical scavenger and antioxidant, in the improvement of antioxidant systems under salt stress. These functions improve photosynthesis, ion homeostasis, and activate a series of downstream signals, such as hormones, nitric oxide (NO) and polyamine metabolism. Melatonin also regulates gene expression responses to salt stress. In this study, we review recent literature and summarize the regulatory roles and signaling networks involving melatonin in response to salt stress in plants. We also discuss genes and gene families involved in the melatonin-mediated salt stress tolerance.

Thermal treatment and modified atmosphere packaging delay chilling injury and preserve the quality of cactus stems (Opuntia ficus-indica Mill.) cv Atlixco

Response surface methodology was applied in order to select the optimal thermal treatment (TT) and modified atmosphere packaging (MAP) needed to preserve minimally processed cactus stems, cv Atlixco. Accordingly, a 42 s/48°C TT together with a 10% CO₂ MAP were selected, and their effects evaluated during storage at 4°C. Controls lost more weight (3.8%) than TT (3.3%), MAP (1.4%), and TT-MAP (1.3%) cactus stems. Chilling injury (CI) symptoms decreased and were of a similar magnitude in both MAP and TT-MAP cactus stems, whereas TT-MAP cladodes were better able to preserve their characteristic green color and freshness, even after 28 days. Biochemically, no differences were detected in the electrolyte leakage (EL) of cactus stems, regardless of treatment. However, the high levels of adenosine triphosphate and of the reduced form of ascorbic acid, especially in MAP and TT-MAP cladodes, suggest that an efficient antioxidant system was present in their tissues throughout storage. PRACTICAL APPLICATIONS: In Mexico, cactus stems have been eaten as vegetables since pre-Hispanic times, and their current status as functional foods has helped them spread to various other countries. As cactus stems possess abundant spines, minimal processing is necessary in order to remove them. Stems must also be kept at 4°C so that their quality and general safety as food items are adequately preserved. However, we previously found that this temperature caused significant CI after just 14 days of storage. The present study, therefore, describes the selection of optimal conditions for the application of a TT that, together with a modified atmosphere (MA), induce tolerance to CI and maintain the quality of stems for up to 28 days. As a result, this work provides the necessary postharvest tools to further expand the distribution and sale of minimally processed cactus stems into domestic and international markets.

Contribution of NRF2 in Gastrointestinal Protection from Oxidative Injury

The human gastrointestinal tract is exposed to a variety of toxic agents, such as Helicobacter pylori (H.pylori), Nonsteroidal Anti-inflammatory Drugs (NSAIDs), gastric acid, enteric pathogenic bacteria, excessive auto immune reactions, and chronic mental stresses. These stressors generate free radicals within the gastrointestinal tissues, causing chronic inflammatory diseases, ulcers, cancers, and functional disturbances. Recent studies have demonstrated that some natural food compounds upregulate the nuclear factor erythroid 2-related factor 2- mediated antioxidant system, ameliorating or preventing these disorders. We have previously shown that dietary intake of sulforaphane-rich broccoli sprouts, ameliorates gastric inflammation induced by H. pylori, prevents NSAIDs-induced small intestinal injury, and improve functional constipation. There have been many other compounds, which enhance the nuclear factor erythroid 2-related factor 2-mediated antioxidant system, sufficient evidence for their clinical efficacy has not yet been provided. In addition, we have to pay attention to some reports, which have shown that excessive stimulation of nuclear factor erythroid 2-related factor 2 enhance chemoresistance and facilitates growth of cancer cells.

Role of NRF2 in protection of the gastrointestinal tract against oxidative stress

The gastrointestinal tract is exposed to a variety of noxious factors, such as Helicobacter pylori, nonsteroidal anti-inflammatory drugs, gastric acid, ischemia-reperfusion, and mental stresses. Theses stressors generate free radicals within gastrointestinal tissues, causing organ injury and functional disturbance. Although the gastrointestinal tract can withstand such oxidative stresses to some extent by enhancing its antioxidant system via nuclear factor erythroid 2-related factor 2-Kelch-like erythroid cell-derived protein with CNC homology-associated protein 1-mediated pathways, acute or chronic exposure to oxidative stress can cause several gastrointestinal tract disorders, such as inflammation, ulcers, cancers, and various functional disturbances. Recent studies have demonstrated that some natural compounds and drugs can upregulate the nuclear factor erythroid 2-related factor 2-mediated antioxidant system, ameliorating or preventing these disorders. Although these compounds may be useful as chemopreventive agents, sufficient evidence for their clinical efficacy has not yet been provided. In addition, it is important to note that excessive nuclear factor erythroid 2-related factor 2 stimulation can be harmful to human health, especially from the standpoint of tumor biology.

Ozonated water reduces susceptibility in tomato plants to Meloidogyne incognita by the modulation of the antioxidant system

Few studies have been carried out on the effect of ozonated water (O₃ wat) on the oxidative stress of root systems and, in particular, in combination with biotic stress. The aim of this study was to determine whether aqueous ozone is effective in the control of root-knot nematode (RKN) infection and to investigate the concomitant changes in the basal defence system. A tomato cultivar susceptible to Meloidogyne incognita was treated with O₃ wat as a soil drench. No negative effects were seen following ozone application in comparison with the control under the exposure conditions used. The treatment reduced significantly the nematode infection rate and induced changes in the morphology of nematode feeding sites, some of which were characterized by visible symptoms of senescence. The antioxidant response, as well as parameters of oxidative damage, were examined in untreated and O₃ wat-treated galls at 2, 4 and 7 days after inoculation and compared with uninfected roots. High levels of reactive oxygen species (ROS), H₂ O₂ and malondialdehyde were generated in galls in response to combined abiotic and biotic stresses. Throughout the experimental period, the activities and relative transcript levels of the antioxidant enzymes catalase, superoxide dismutase and ascorbate peroxidase produced different responses when exposed to ozone treatment and/or infection. The results demonstrate how O₃ wat protects tomato against the RKN M. incognita through the modulation of basal defence mechanisms.

The Architecture of Thiol Antioxidant Systems among Invertebrate Parasites

The use of oxygen as the final electron acceptor in aerobic organisms results in an improvement in the energy metabolism. However, as a byproduct of the aerobic metabolism, reactive oxygen species are produced, leaving to the potential risk of an oxidative stress. To contend with such harmful compounds, living organisms have evolved antioxidant strategies. In this sense, the thiol-dependent antioxidant defense systems play a central role. In all cases, cysteine constitutes the major building block on which such systems are constructed, being present in redox substrates such as glutathione, thioredoxin, and trypanothione, as well as at the catalytic site of a variety of reductases and peroxidases. In some cases, the related selenocysteine was incorporated at selected proteins. In invertebrate parasites, antioxidant systems have evolved in a diversity of both substrates and enzymes, representing a potential area in the design of anti-parasite strategies. The present review focus on the organization of the thiol-based antioxidant systems in invertebrate parasites. Differences between these taxa and its final mammal host is stressed. An understanding of the antioxidant defense mechanisms in this kind of parasites, as well as their interactions with the specific host is crucial in the design of drugs targeting these organisms.

Influence of Oxidative Stress on Biocontrol Activity of Cryptococcus laurentii against Blue Mold on Peach Fruit

The limitations of chemical fungicides for the control of postharvest diseases have recently become more apparent. The utilization of antagonistic microorganisms is a promising alternative to that of fungicides to control postharvest decay. In previous studies, the antagonistic yeast Cryptococcus laurentii has shown excellent effects of biocontrol and great potential for practical application. Adverse conditions, such as oxidative stress, limit the practical application of antagonistic yeast. In this study, we investigated the oxidative stress tolerance of C. laurentii and the associated mechanisms. The results indicated that exogenous oxidative stress has a significant effect on the viability and biocontrol efficiency of C. laurentii. H2O2-induced oxidative stress led to the accumulation of reactive oxygen species. The results of flow cytometric analysis suggested that apoptosis is responsible for the reduced survival rate of C. laurentii under oxidative stress. Using tests of antioxidant activity, we found that C. laurentii could employ enzymatic systems to resist exogenous oxidative stress. The addition of exogenous glutathione, a non-enzymatic antioxidant, to the media can significantly enhance oxidative tolerance and biocontrol efficiency of C. laurentii.

Sub-toxic Ethanol Exposure Modulates Gene Expression and Enzyme Activity of Antioxidant Systems to Provide Neuroprotection in Hippocampal HT22 Cells

Ethanol is known to cause severe systemic damage often explained as secondary to oxidative stress. Brain is particularly vulnerable to ethanol-induced reactive oxygen species (ROS) because the high amounts of lipids, and because nerve cell membranes contain high amounts of peroxidable fatty acids. Usually these effects of ethanol are associated to high and/or chronic exposure to ethanol. However, as we show in this manuscript, a low and acute dose of ethanol trigger a completely different response in hippocampal cells. Thus, we have observed that 0.1% ethanol exposure to HT22 cells, a murine hippocampal-derived cell line, increases the transcriptional expression of different genes belonging to the classical, glutathione/glutaredoxin and thioredoxin/peroxiredoxin antioxidant systems, these including Sod1, Sod2, Gpx1, Gclc, and Txnrd1. Paralleling these changes, enzyme activities of total superoxide dismutase (tSOD), catalase, total glutathione peroxidase (tGPx), glutathione-S-reductase (GSR), and total thioredoxin reductase (tTXNRD), were all increased, while the generation of thiobarbituric acid reactive substances (TBARS), as indicators of lipid peroxidation, and glutathione levels remained unaltered. Ethanol exposure did not affect cell viability or cell growing as assessed by real-time cell culture monitoring, indicating that low ethanol doses are not deleterious for hippocampal cells, but rather prevented glutamate-induced excitotoxicity. In summary, we conclude that sub-toxic exposure to ethanol may well be neuroprotective against oxidative insults in hippocampal cells.

Triacontanol Reduces Transplanting Shock in Machine-Transplanted Rice by Improving the Growth and Antioxidant Systems

Machine transplantation results in serious transplant shock in seedlings and results in a longer recover stage, which negatively impacts the growth of low-position tillers and the yield of machine-transplanted rice. A barrel experiment was conducted to examine the effect of the foliar application of triacontanol (TRIA) on machine-transplanted rice during the recovery stage. TRIA (0, 1, 5, and 10 μM) was sprayed over leaves 2 days before transplanting. The chlorophyll content, sucrose content, oxidative damage, antioxidant enzyme levels, glutathione (GSH), and ascorbate (ASA) redox states, tiller dynamics and yield components of the plants were investigated. The results show that foliar-applied TRIA significantly alleviates the growth inhibition and oxidative damage caused by transplant shock. Furthermore, the application of TRIA increased the chlorophyll and sucrose contents of the plants. Importantly, TRIA not only significantly improved the activity of catalase (CAT) and guaiacol peroxidase (POD), demonstrating that POD can play an important role in scavenging H2O2 during the recovery stage, but it also enhanced the redox states of ASA and GSH by regulating the activities of enzymes involved in the ASA-GSH cycle, such as ascorbate peroxidase (APX) and glutathione reductase (GR). A dose of 10 μM TRIA was the most efficient in reducing the negative effects of transplant shock, increasing the panicles, grain filling, and grain yield per hill by 17.80, 5.86, and 16.49%, respectively. These results suggest that TRIA acts to reduce transplant shock in association with the regulation of the redox states of ASA and GSH and antioxidant enzymes and serves as an effective antioxidant to maintain photosynthetic capacity and promote the occurrence of low tillers.

Phaseolus vulgaris L. Seedlings Exposed to Prometryn Herbicide Contaminated Soil Trigger an Oxidative Stress Response

Herbicides from the family of S-triazines, such as prometryn, have been widely used in crop production and can constitute an environmental pollution in both water and soil. As a valuable crop, the common bean (Phaseolus vulgaris L.) is grown all over the world and could be exposed to such herbicides. We wanted to investigate the possible stress sustained by the common bean growing in prometryn-polluted soil. Two situations were observed: when soil was treated with ≥100 μM prometryn, some, but not all, measured growth parameters were affected in a dose-dependent manner. Growth was reduced, and photosynthetic pigments and photosynthetic products were less accumulated when soil was treated with ≥100 μM prometryn. Reactive oxygen species (ROS) produced had a deleterious effect, as seen by the accumulation of oxidized lipid in the form of malondialdehyde (MDA). Higher prometryn (500 μM) concentrations had a disastrous effect, reducing antioxidant activities. At a low (10 μM) concentration, prometryn increased antioxidant enzymatic activities without affecting plant growth or MDA production. Gene expression of proline metabolism genes and proline accumulation confirm that bean plants respond to a stress according to the prometryn concentration. Physiological responses such as antioxidative enzymes APX, CAT, and the enzyme implicated in the metabolization of xenobiotics, GST, were increased at 10 and 100 μM, which indicated a prevention of deleterious effects of prometryn, suggesting that bean is a suitable material both for herbicide pollution sensing and as a crop on a low level of herbicide pollution.

Differences in Redox Regulatory Systems in Human Lung and Liver Tumors Suggest Different Avenues for Therapy

A common characteristic of many cancer cells is that they suffer from oxidative stress. They, therefore, require effective redox regulatory systems to combat the higher levels of reactive oxygen species that accompany accelerated growth compared to the normal cells of origin. An elevated dependence on these systems in cancers suggests that targeting these systems may provide an avenue for retarding the malignancy process. Herein, we examined the redox regulatory systems in human liver and lung cancers by comparing human lung adenocarcinoma and liver carcinoma to their respective surrounding normal tissues. Significant differences were found in the two major redox systems, the thioredoxin and glutathione systems. Thioredoxin reductase 1 levels were elevated in both malignancies, but thioredoxin was highly upregulated in lung tumor and only slightly upregulated in liver tumor, while peroxiredoxin 1 was highly elevated in lung tumor, but downregulated in liver tumor. There were also major differences within the glutathione system between the malignancies and their normal tissues. The data suggest a greater dependence of liver on either the thioredoxin or glutathione system to drive the malignancy, while lung cancer appeared to depend primarily on the thioredoxin system.

Green tea (Camellia sinensis) alleviates arsenic-induced damages to DNA and intestinal tissues in rat and in situ intestinal loop by reinforcing antioxidant system

This study elucidates the protective role of Green tea (Camellia sinensis or CS) against arsenic-induced mutagenic DNA-breakage/intestinal (small) damages in female rats. Intestinal epithelial cells receive ingested arsenic initially. Though, the possibility of damages in this tissue is immense and the therapeutic strategies against this damage are of great concern, reports on either issue are scanty. Our earlier study on arsenic-exposed human unveils a link between carcinogenesis and mutagenic DNA damage. Here, we demonstrate that supplementation of CS-extract (10 mg/mL water) with NaAsO2 (0.6 ppm)/100 g b.w. for 28 days to rats offered a significant protection against arsenic-induced oxidative damages to DNA and intestinal (small) tissues by buttressing antioxidant systems. Necrotic and apoptotic damages and their CS-protection are shown in DNA-fragmentation, comet-assay, and histoarchitecture (hematoxylin and eosin and periodic acid-schiff staining) results. Only arsenic exposure significantly decreased intestinal superoxide dismutase, catalase activities, and level of soluble thiol with a concomitant increase in malondialdehyde/conjugated dienes. Alteration of serum necrotic marker lactate dehydrogenase and the metabolic inflammatory marker c-reactive protein also indicate the impairment may be occurring at transcription and/or cellular signal transduction level. In addition, in situ incubation in rat intestinal loop filled for 24 h with NaAsO2 alone (250 µM) or with aqueous CS-extract (250 mg/mL) suggests that small intestinal epithelial cells are significantly protected by CS against arsenic-associated necrotic/mutagenic damages, which is observed in DNA-breakage studies. In conclusion, besides intensifying endogenous antioxidant system, CS polyphenols also offer a direct role on free radical scavenging activity that is associated to the protection from mutagenic DNA-breakages and prevention of tissue necrosis/carcinogenesis generated by arsenic.

Postharvest Exogenous Application of Abscisic Acid Reduces Internal Browning in Pineapple

Internal browning (IB) is a postharvest physiological disorder causing economic losses in pineapple, but there is no effective control measure. In this study, postharvest application of 380 μM abscisic acid (ABA) reduced IB incidence by 23.4-86.3% and maintained quality in pineapple fruit. ABA reduced phenolic contents and polyphenol oxidase and phenylalanine ammonia lyase activities; increased catalase and peroxidase activities; and decreased O2(·-), H2O2, and malondialdehyde levels. This suggests ABA could control IB through inhibiting phenolics biosynthesis and oxidation and enhancing antioxidant capability. Furthermore, the efficacy of IB control by ABA was not obviously affected by tungstate, ABA biosynthesis inhibitor, nor by diphenylene iodonium, NADPH oxidase inhibitor, nor by lanthanum chloride, calcium channel blocker, suggesting that ABA is sufficient for controlling IB. This process might not involve H2O2 generation, but could involve the Ca(2+) channels activation. These results provide potential for developing effective measures for controlling IB in pineapple.

Redox interplay between mitochondria and peroxisomes

Reduction-oxidation or “redox” reactions are an integral part of a broad range of cellular processes such as gene expression, energy metabolism, protein import and folding, and autophagy. As many of these processes are intimately linked with cell fate decisions, transient or chronic changes in cellular redox equilibrium are likely to contribute to the initiation and progression of a plethora of human diseases. Since a long time, it is known that mitochondria are major players in redox regulation and signaling. More recently, it has become clear that also peroxisomes have the capacity to impact redox-linked physiological processes. To serve this function, peroxisomes cooperate with other organelles, including mitochondria. This review provides a comprehensive picture of what is currently known about the redox interplay between mitochondria and peroxisomes in mammals. We first outline the pro- and antioxidant systems of both organelles and how they may function as redox signaling nodes. Next, we critically review and discuss emerging evidence that peroxisomes and mitochondria share an intricate redox-sensitive relationship and cooperate in cell fate decisions. Key issues include possible physiological roles, messengers, and mechanisms. We also provide examples of how data mining of publicly-available datasets from “omics” technologies can be a powerful means to gain additional insights into potential redox signaling pathways between peroxisomes and mitochondria. Finally, we highlight the need for more studies that seek to clarify the mechanisms of how mitochondria may act as dynamic receivers, integrators, and transmitters of peroxisome-derived mediators of oxidative stress. The outcome of such studies may open up exciting new avenues for the community of researchers working on cellular responses to organelle-derived oxidative stress, a research field in which the role of peroxisomes is currently highly underestimated and an issue of discussion.

Expression of TaWRKY44, a wheat WRKY gene, in transgenic tobacco confers multiple abiotic stress tolerances

The WRKY transcription factors have been reported to be involved in various plant physiological and biochemical processes. In this study, we successfully assembled 10 unigenes from expressed sequence tags (ESTs) of wheat and designated them as TaWRKY44-TaWRKY53, respectively. Among these genes, a subgroup I gene, TaWRKY44, was found to be upregulated by treatments with PEG6000, NaCl, 4°C, abscisic acid (ABA), H2O2 and gibberellin (GA). The TaWRKY44-GFP fusion protein was localized to the nucleus of onion epidermal cells, and TaWRKY44 was able to bind to the core DNA sequences of TTGACC and TTAACC in yeast. The N-terminal of TaWRKY44 showed transcriptional activation activity. Expression of TaWRKY44 in tobacco plants conferred drought and salt tolerance and transgenic tobacco exhibited a higher survival rate, relative water content (RWC), soluble sugar, proline and superoxide dismutase (SOD) content, as well as higher activities of catalase (CAT) and peroxidase (POD), but less ion leakage (IL), lower contents of malondialdehyde (MDA), and H2O2. In addition, expression of TaWRKY44 also increased the seed germination rate in the transgenic lines under osmotic stress conditions while exhibiting a lower H2O2 content and higher SOD, CAT, and POD activities. Expression of TaWRKY44 upregulated the expression of some reactive oxygen species (ROS)-related genes and stress-responsive genes in tobacco under osmotic stresses. These data demonstrate that TaWRKY44 may act as a positive regulator in drought/salt/osmotic stress responses by either efficient ROS elimination through direct or indirect activation of the cellular antioxidant systems or activation of stress-associated gene expression.

Restoring redox balance enhances contractility in heart trabeculae from type 2 diabetic rats exposed to high glucose

Hearts from type 2 diabetic (T2DM) subjects are chronically subjected to hyperglycemia and hyperlipidemia, both thought to contribute to oxidizing conditions and contractile dysfunction. How redox alterations and contractility interrelate, ultimately diminishing T2DM heart function, remains poorly understood. Herein we tested whether the fatty acid palmitate (Palm), in addition to its energetic contribution, rescues function by improving redox [glutathione (GSH), NAD(P)H, less oxidative stress] in T2DM rat heart trabeculae subjected to high glucose. Using cardiac trabeculae from Zucker Diabetic Fatty (ZDF) rats, we assessed the impact of low glucose (EG) and high glucose (HG), in absence or presence of Palm or insulin, on force development, energetics, and redox responses. We found that in EG ZDF and lean trabeculae displayed similar contractile work, yield of contractile work (Ycw), representing the ratio of force time integral over rate of O2 consumption. Conversely, HG had a negative impact on Ycw, whereas Palm, but not insulin, completely prevented contractile loss. This effect was associated with higher GSH, less oxidative stress, and augmented matrix GSH/thioredoxin (Trx) in ZDF mitochondria. Restoration of myocardial redox with GSH ethyl ester also rescued ZDF contractile function in HG, independently from Palm. These results support the idea that maintained redox balance, via increased GSH and Trx antioxidant activities to resist oxidative stress, is an essential protective response of the diabetic heart to keep contractile function.

Beneficial effects of silibinin against the progression of metabolic syndrome, increased oxidative stress, and liver steatosis in Psammomys obesus, a relevant animal model of human obesity and diabetes

BACKGROUND

Insulin resistance and oxidative stress are major pathogenic mechanisms leading to chronic liver diseases in diabetic subjects. The gerbil Psammomys obesus is a unique model of nutritional diabetes resembling the disease in humans. This study investigated whether the natural ingredient silibinin, known as hepatoprotective, could decrease oxidative stress and reduce liver damage in obese gerbils.

METHODS

Control animals were fed their vegetable-based low caloric diet while two other rat groups ingested a high calorie diet for 14 weeks. Silibinin, or its vehicle, was administrated by gastric intubation (100 mg/kg per day) from the 7th week of treatment, which corresponds to an established insulin resistance state. At the end of the experiments, the hepatic biochemical profile, markers of oxidative stress in either plasma or liver tissue, and histological alterations were examined.

RESULTS

Diabetic P. obesus displayed many metabolic disturbances (hyperinsulinemia, hyperglycemia, dyslipidemia), which were aggravated for the last 8 weeks. These events were coupled with greater oxidative stress (decline in glutathione, rise in lipoperoxidation). In addition, glutathione peroxidase activity was reduced while the level of superoxide dismutase was elevated. Interestingly, treatment with silibinin alleviated most of the metabolic defects, especially high triglyceride levels, reduced insulin resistance and largely restored antioxidant status. Also, Masson's trichrome staining revealed distinct steatosis, yet silibinin partially reversed this manifestation.

CONCLUSION

Silibinin affords substantial protection against the progression of insulin resistance in Type 2 diabetes mellitus for P. obesus by hampering the oxidative process and improving hepatic metabolism.

Effects of aluminum on light energy utilization and photoprotective systems in citrus leaves

BACKGROUND AND AIMS

Under high photon flux, excitation energy may be in excess in aluminum (Al)-treated leaves, which use a smaller fraction of the absorbed light in electron transport due to decreased CO2 assimilation compared with normal leaves. The objectives of this study were to test the hypothesis that the antioxidant systems are up-regulated in Al-treated citrus leaves and correlate with protection from photoxidative damage, and to test whether xanthophyll cycle-dependent thermal energy dissipation is involved in dissipating excess excitation energy. *

METHODS

'Cleopatra' tangerine seedlings were fertilized and irrigated daily for 8 weeks with quarter-strength Hoagland's nutrient solution containing Al at a concentration of 0 or 2 mM from Al2(SO4)3.18H2O. Thereafter, leaf absorptance, chlorophyll (Chl) fluorescence, Al, pigments, antioxidant enzymes and metabolites were measured on fully expanded leaves. *

KEY RESULTS

Compared with control leaves, energy was in excess in Al-treated leaves, which had smaller thermal energy dissipation, indicated by non-photochemical quenching (NPQ). In contrast, conversion of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) at midday increased in both treatments, but especially in Al-treated leaves, although A + Z accounted for less 40 % of the total xanthophyll cycle pool in them. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and catalase (CAT), and concentrations of ascorbate (AsA), dehydroascorbate (DASA), reduced glutathione (GSH) and oxidized glutathione (GSSG) were higher in Al-treated than in control leaves. *

CONCLUSIONS

These results corroborate the hypothesis that, compared with control leaves, antioxidant systems are up-regulated in Al-treated citrus leaves and protect from photoxidative damage, whereas thermal energy dissipation was decreased. Thus, antioxidant systems are more important than thermal energy dissipation in dissipating excess excitation energy in Al-treated citrus leaves.