Ex-Vivo Trans-Corneal and Trans-Scleral Diffusion Studies with Ocular Formulations of Glutathione as an Antioxidant Treatment for Ocular Diseases

Schizophrenia (SZ) and bipolar disorder (BD) are classified as two distinct diseases. However, accumulating evidence shows that both disorders share genetic, pathological, and epidemiological characteristics. Based on genetic and functional findings, redox dysregulation due to an imbalance between pro-oxidants and antioxidant defense mechanisms has been proposed as a risk factor contributing to their pathophysiology. Altered antioxidant systems and signs of increased oxidative stress are observed in peripheral tissues and brains of SZ and BD patients, including abnormal prefrontal levels of glutathione (GSH), the major cellular redox regulator and antioxidant. Here we review experimental data from rodent models demonstrating that permanent as well as transient GSH deficit results in behavioral, morphological, electrophysiological, and neurochemical alterations analogous to pathologies observed in patients. Mice with GSH deficit display increased stress reactivity, altered social behavior, impaired prepulse inhibition, and exaggerated locomotor responses to psychostimulant injection. These behavioral changes are accompanied by N-methyl-D-aspartate receptor hypofunction, elevated glutamate levels, impairment of parvalbumin GABA interneurons, abnormal neuronal synchronization, altered dopamine neurotransmission, and deficient myelination. Treatment with the GSH precursor and antioxidant N-acetylcysteine normalizes some of those deficits in mice, but also improves SZ and BD symptoms when given as adjunct to antipsychotic medication. These data demonstrate the usefulness of GSH-deficient rodent models to identify the mechanisms by which a redox imbalance could contribute to the development of SZ and BD pathophysiologies, and to develop novel therapeutic approaches based on antioxidant and redox regulator compounds.

Different strategies including the exogenous use of micronutrient-chelated amino acids are being employed for better crop yield with limited fresh water for irrigation. The present study was conducted to assess the effects of foliar-applied Zn-lysine (Zn-Lys) on maize growth and yield under limited irrigation, in relation to physio-biochemical mechanisms such as the plant–water relations, photosynthetic efficiency, antioxidant defense mechanism, amino acid accumulation and nutrient acquisition. The experiment comprised two maize cultivars (MMRI and Pearl), two irrigation levels and three levels of Zn-Lys (0.25, 0.5 and 0.75%). Zn-Lys fertigation was found to be effective in reducing the negative impacts of limited water supply on grain yield, associated with improved photosynthetic efficiency, water relations, antioxidative defense mechanism and reduced lipid peroxidation in both maize cultivars. Zn-Lys-induced improvement in antioxidative mechanisms was associated with improved content of non-enzymatic antioxidants and activities of antioxidant enzymes. Foliar-fertigation with Zn-Lys also significantly improved the contents of various amino acids including Lys, as well as uptake of nutrients in both maize cultivars. In conclusion, the 0.5% level of Zn-Lys was found to be effective in ameliorating the negative impacts of water stress for better grain yield in both maize cultivars that can also be used as an important environment-friendly source of Zn to fulfill maize Zn deficiency.

Oxidative stresses commonly exist in natural environments, and microbes have developed a variety of defensive systems to counteract such events. Although increasing evidence has shown that high hydrostatic pressure (HHP) and low temperature (LT) induce antioxidant defense responses in cells, there is no direct evidence to prove the connection between antioxidant defense mechanisms and the adaptation of bacteria to HHP and LT. In this study, using the wild-type (WT) strain of a deep-sea bacterium, Shewanella piezotolerans WP3, as an ancestor, we obtained a mutant, OE100, with an enhanced antioxidant defense capacity by experimental evolution under H2O2 stress. Notably, OE100 exhibited better tolerance not only to H2O2 stress but also to HHP and LT (20 MPa and 4°C, respectively). Whole-genome sequencing identified a deletion mutation in the oxyR gene, which encodes the transcription factor that controls the oxidative stress response. Comparative transcriptome analysis showed that the genes associated with oxidative stress defense, anaerobic respiration, DNA repair, and the synthesis of flagella and bacteriophage were differentially expressed in OE100 compared with the WT at 20 MPa and 4°C. Genetic analysis of oxyR and ccpA2 indicated that the OxyR-regulated cytochrome c peroxidase CcpA2 significantly contributed to the adaptation of WP3 to HHP and LT. Taken together, these results confirmed the inherent relationship between antioxidant defense mechanisms and the adaptation of a benthic microorganism to HHP and LT.IMPORTANCE Oxidative stress exists in various niches, including the deep-sea ecosystem, which is an extreme environment with conditions of HHP and predominantly LT. Although previous studies have shown that HHP and LT induce antioxidant defense responses in cells, direct evidence to prove the connection between antioxidant defense mechanisms and the adaptation of bacteria to HHP and LT is lacking. In this work, using the deep-sea bacterium Shewanella piezotolerans WP3 as a model, we proved that enhancement of the adaptability of WP3 to HHP and LT can benefit from its antioxidant defense mechanism, which provided useful insight into the ecological roles of antioxidant genes in a benthic microorganism and contributed to an improved understanding of microbial adaptation strategies in deep-sea environments.

23 - Biostimulants in the alleviation of metal toxicity: conclusion and future perspective

Free radicals and other oxidants have gained importance in the field of biology due to their central role in various physiological conditions as well as their implication in a diverse range of diseases. Biological free radicals, notably reactive oxygen species (ROS) and reactive nitrogen species (RNS) are derived from both endogenous sources (mitochondria, peroxisomes, endoplasmic reticulum, phagocytic cells etc.) and exogenous sources (pollution, alcohol, tobacco smoke, heavy metals, transition metals, industrial solvents, pesticides, certain drugs like halothane, paracetamol, and radiation). However, when their production overwhelms the body?s antioxidant defences, a state of oxidative stress develops. Antioxidants- both enzymatic (e.g., superoxide dismutase, catalase, glutathione peroxidase) and non-enzymatic (e.g., vitamins C and E, glutathione, polyphenols)- serve as critical protective systems that neutralize free radicals and prevent biomolecular damage. Effective antioxidant defences are crucial in mitigating free radical-induced cellular damage and maintaining biological homeostasis. The free radicals induced oxidative stress can damage critical biomolecules including DNA, lipids, and proteins, has been reported to be involved in several diseased conditions such as diabetes mellitus, neurodegenerative disorders (Parkinson?s disease-PD, Alzheimer?s disease-AD and Multiple sclerosis-MS), cardiovascular diseases (atherosclerosis and hypertension), respiratory diseases (asthma), cataract development, rheumatoid arthritis and in various cancers (colorectal, prostate, breast, lung, bladder cancers). This review deals with the general aspects of free radicals and antioxidant defence mechanism and the role of free radicals in the development of pathogenesis of some common diseases.

Climate change has increased the overall impact of abiotic stress conditions such as drought, salinity, and extreme temperatures on plants. Abiotic stress adversely affects the growth, development, crop yield, and productivity of plants. When plants are subjected to various environmental stress conditions, the balance between the production of reactive oxygen species and its detoxification through antioxidant mechanisms is disturbed. The extent of disturbance depends on the severity, intensity, and duration of abiotic stress. The equilibrium between the production and elimination of reactive oxygen species is maintained due to both enzymatic and non-enzymatic antioxidative defense mechanisms. Non-enzymatic antioxidants include both lipid-soluble (α-tocopherol and β-carotene) and water-soluble (glutathione, ascorbate, etc.) antioxidants. Ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) are major enzymatic antioxidants that are essential for ROS homeostasis. In this review, we intend to discuss various antioxidative defense approaches used to improve abiotic stress tolerance in plants and the mechanism of action of the genes or enzymes involved.

Practical and cost-effective food safety and production methods are essential, as huge areas of arable land are contaminated through heavy metals, including cadmium (Cd) pollution worldwide. This study was performed to assess impacts of dissimilar doses of trehalose (Tre) (0, 25, 50 mM) as foliar spray on wheat plants grown under different Cd stress levels (0, 2.5, 5, 10 mg/kg), considering different growth, photosynthetic attributes and antioxidative defense mechanism in relation with the uptake of Cd to different plant parts. A considerable reduction was detected in growth, biomass, and chlorophyll contents under Cd stress linked with boosted lipid peroxidation, electrolyte leakage (EL), and the uptake of Cd uptake to various parts of plants. Foliar-applied Tre enhanced the hostile possessions of Cd on all studied growing, photosynthetic pigments, and gas exchange attributes associated with reduced lipid peroxidation due to improved antioxidative defense mechanism and reduced Cd uptake to many parts of plant, as well as in grains. Foliar application of Tre reduced the uptake of Cd by 31% in roots, 33% in shoots, and 41% in grains as compared with respective control plants. The study findings propose Tre as a possible contender in reducing Cd stress in wheat with better growth by improving the physiobiochemical and antioxidative mechanisms and maintained better grain quality due to reduced accumulation of Cd that will help to reduce the Cd toxicity in wheat consumers.

Oxidative and antioxidative mechanisms in oral cancer and precancer: A review

To investigate Fe deficiency tolerance in tomato cultivars, quantification of proteins and genes involved in Fe metabolism and antioxidant mechanisms were performed in “Roggusanmaru” and “Super Doterang”. Fe deficiency (Moderate, low and –Fe) significantly decreased the biomass, total, and apoplastic Fe concentration of “Roggusanmaru”, while a slight variation was observed in “Super Doterang” cultivar. The quantity of important photosynthetic pigments such as total chlorophyll and carotenoid contents significantly decreased in “Roggusanmaru” than “Super Doterang” cultivar. The total protein profile in leaves and roots determines that “Super Doterang” exhibited an optimal tolerance to Fe deficiency compared to “Roggusanmaru” cultivar. A reduction in expression of PSI (photosystem I), PSII (photosystem II) super-complexes and related thylakoid protein contents were detected in “Roggusanmaru” than “Super Doterang” cultivar. Moreover, the relative gene expression of SlPSI and SlPSII were well maintained in “Super Doterang” than “Roggusanmaru” cultivar. The relative expression of genes involved in Fe-transport (SlIRT1 and SlIRT2) and Fe(III) chelates reductase oxidase (SlFRO1) were relatively reduced in “Roggusanmaru”, while increased in “Super Doterang” cultivar under Fe deficient conditions. The H+-ATPase relative gene expression (SlAHA1) in roots were maintained in “Super Doterang” compared to “Roggusanmaru”. Furthermore, the gene expressions involved in antioxidant defense mechanisms (SlSOD, SlAPX and SlCAT) in leaves and roots showed that these genes were highly increased in “Super Doterang”, whereas decreased in “Roggusanmaru” cultivar under Fe deficiency. The present study suggested that “Super Doterang” is better tomato cultivar than “Roggusanmaru” for calcareous soils.

To counteract oxidative stress and associated brain diseases, antioxidant systems rescue neuronal cells from oxidative stress by neutralizing reactive oxygen species and preserving gene regulation. It is necessary to understand the communication and interactions between brain cells, including neurons, astrocytes and microglia, to understand oxidative stress and antioxidant mechanisms. Here, the role of glia in the protection of neurons against oxidative injury and glia–neuron crosstalk to maintain antioxidant defense mechanisms and brain protection are reviewed. The first part of this review focuses on the role of glia in the morphological and physiological changes required for brain homeostasis under oxidative stress and antioxidant defense mechanisms. The second part focuses on the essential crosstalk between neurons and glia for redox balance in the brain for protection against oxidative stress.

COVID-19 is caused by the Severe Acute Respiratory Distress Syndrome Coronavirus 2. Since the antioxidant mechanisms such as glutathione peroxidase or superoxide dismutase are downregulated during infection by the virus, there is an imbalance in the oxidant-antioxidant system. In this study we aimed to identify the effect of COVID-19 on the antioxidant defense mechanism by comparing the concentrations of antioxidants and microminerals in COVID-19 patients and healthy controls. This cross-sectional analytical study involved 200 patients at Kasturba Hospital, Manipal University. The serum concentrations of antioxidants and minerals were determined to establish the impact of COVID-19 on antioxidants mechanism and nutrient status in COVID-19 patients. The serum concentrations of GPX (10.36 ± 2.70 ≥ 5.82 ± 1.64 mKAT/L, p < 0.0001) and copper (2192.5 ± 449.8 ≥ 782.15 ± 106.5 µg/dL, p < 0.0001) were significantly greater, and zinc (34.78 ± 4.5 ≤ 81.07 ± 10.13 µg/dL, p < 0.0001) was significantly less, in the study group than in controls. The Pearson correlation between serum SOD and zinc was significant (r = 0.491, p < 0.0001) indicating the importance of zinc in maintaining and improving SOD activity. No significant correlations were observed between copper and SOD (r = -0.089) or iron and CAT (r = -0.027). Our study demonstrated the expected increase in oxidant-radical production during COVID-19 by estimating the altered concentrations of antioxidants and the minerals required to neutralize the elevated ROS. This finding is not novel but adds to the existing literature, which recommends nutritional supplementation of microminerals and antioxidants.

Limbal stem cells (LSCs) are a quiescent cell population responsible for the renewal of the corneal epithelium. Their deficiency is responsible for the conjunctivization of the cornea that is seen in different ocular pathologies, both in humans and in the canine species. The canine species represents an interesting preclinical animal model in ocular surface pathologies. However, the role of LSCs in physiological and pathological conditions in canine species is not well understood. Our objective was to characterize for the first time the soluble factors and the proteomic profile of the secretome and exosomes of canine LSCs (cLSCs). In addition, given the important role that fibroblasts play in the repair of the ocular surface, we evaluated the influence of the secretome and exosomes of cLSCs on their proliferation in vitro. Our results demonstrated a secretory profile of cLSCs with high concentrations of MCP-1, IL-8, VEGF-A, and IL-10, as well as significant production of exosomes. Regarding the proteomic profile, 646 total proteins in the secretome and 356 in exosomes were involved in different biological processes. Functionally, the cLSC secretome showed an inhibitory effect on the proliferation of fibroblasts in vitro, which the exosomes did not. These results open the door to new studies on the possible use of the cLSC secretome or some of its components to treat certain pathologies of the ocular surface in canine species.

The present experiment was carried out to study the influences of exogenously-applied nitric oxide (NO) donor sodium nitroprusside (SNP) and hydrogen peroxide (H2O2) as seed primers on growth and yield in relation with different physio-biochemical parameters, antioxidant activities, and osmolyte accumulation in wheat plants grown under control (100% field capacity) and water stress (60% field capacity) conditions. During soaking, the seeds were covered and kept in completely dark. Drought stress markedly reduced the plant growth, grain yield, leaf photosynthetic pigments, total phenolic content (TPC), total soluble proteins (TSP), leaf water potential (Ψw), leaf turgor potential (Ψp), osmotic potential (Ψs), and leaf relative water content (LRWC), while it increased the activities of enzymatic antioxidants and the accumulation of leaf ascorbic acid (AsA), proline (Pro), glycine betaine (GB), malondialdehyde (MDA), and H2O2. However, seed priming with SNP and H2O2 alone and in combination mitigated the deleterious effects of water stress on growth and yield by improving the Ψw, Ψs, Ψp, photosynthetic pigments, osmolytes accumulation (GB and Pro), TSP, and the antioxidative defense mechanism. Furthermore, the application of NO and H2O2 as seed primers also reduced the accumulation of H2O2 and MDA contents. The effectiveness was treatment-specific and the combined application was also found to be effective. The results revealed that exogenous application of NO and H2O2 was effective in increasing the tolerance of wheat plants under drought stress in terms of growth and grain yield by regulating plant–water relations, the antioxidative defense mechanism, and accumulation of osmolytes, and by reducing the membrane lipid peroxidation.

Different techniques are being employed to reduce the adverse effects of water stress on seed yield and quality of crop plants. The current study aimed to improve the water stress tolerance of field-grown sunflower by foliar-supplied ecofriendly iron-chelated aspartate (Fe-Asp) in comparison with FeSO4. Water stress decreased the plant growth and yield, accompanied with disturbed water relations, nutrient acquisition, accumulation of amino acids, and antioxidative defense mechanisms. However, lipid peroxidation, total anthocyanin, and photosynthetic pigments were increased. Fertigation of FeSO4 and Fe-Asp as foliar sprays proved effective to reduce the negativities of limited irrigation on biomass production and seed yield, accompanied with a reduction in lipid peroxidation and improvements in water relations, antioxidative defense mechanisms, and leaf photosynthetic pigments. In comparison with FeSO4, foliary applied Fe-Asp better improved the plant water relations with more accumulation of essential amino acids and nutrient acquisition, especially leaf aspartate (Asp) and Fe accumulation which showed better translocation. Overall, foliary applied Fe-Asp proved better for induction of drought tolerance in sunflower plants as compared with FeSO4. The study recommended the use of the ecofriendly Fe-Asp as a foliar spray for better growth and production of sunflower under limited irrigation.

Accumulating evidence from invitro, invivo, clinical and epidemiological studies shows promising results for the use of statins against many cancers including breast carcinoma. However, the molecular mechanisms responsible for the anti-proliferative and anti-invasive properties of statins still remain elusive. In this study, we investigated the involvement of nitric oxide, iron homeostasis and antioxidant defence mechanisms in mediating the anti-proliferative and anti-invasive properties of hydrophobic statins in MDA-MB-231, MDA-MB-453 and BT-549 metastatic triple negative breast cancer cells. Fluvastatin and simvastatin significantly increased cytotoxicity which was reversed with mevalonate. Interestingly, fluvastatin downregulated transferrin receptor (TfR1), with a concomitant depletion of intracellular iron levels in these cells. Statin-induced effects were mimicked by geranylgeranyl transferase inhibitor (GGTI-298) but not farnesyl transferase inhibitor (FTI-277). Further, it was observed that TfR1 downregulation is mediated by increased nitric oxide levels via inducible nitric oxide synthase (iNOS) expression. NOS inhibitors (asymmetric dimethylarginine and 1400W) counteracted and sepiapterin, a precursor of tetrahydrobiopterin, exacerbated statin-induced depletion of intracellular iron levels. Notably, fluvastatin increased manganese superoxide dismutase (by repressing the transcription factor DNA damage-binding protein 2), catalase and glutathione which, in turn, diminished H2 O2 levels. Fluvastatin-induced downregulation of TfR1, matrix metalloproteinase-2, -9 and inhibition of invasion were reversed in the presence of aminotriazole, a specific inhibitor of catalase. Finally, we conclude that fluvastatin, by altering iron homeostasis, nitric oxide generation and antioxidant defence mechanisms, induces triple negative breast cancer cell death.