Vitamin C and vitamin E restore the resistance of GSH-depleted lens cells to H2O2

New vaccination approach using formalin-killed Streptococcus pyogenes vaccine on the liver of Oreochromis niloticus fingerlings

Newly synthesized vaccines prepared from formalin-killed bacteria Streptococcus pyogenes were investigated in the current study to evaluate the effectiveness of the newly synthesized vaccine as well as their safety by injected intraperitoneal. The study involved several steps 1st step is the preparation of the vaccine followed by the 2nd step: Evaluate the effectiveness and vaccine safety against pathogenic S. pyogenes through 4 different groups including control (Group I). Group II (Bacterial, infected group), Group III (Vaccine), and the Last group was the challenged group after the vaccination (Vacc + Bac). Different Immunological and biochemical parameters were measured in addition to hematological and histopathological examinations. For example, oxidative/antioxidants, inflammatory biomarkers, fragmentation and cell damage, and finally the histopathological study. The current study showed an increase in all oxidative, inflammatory, and cell damage (DNA fragmentation assays), additionally markedly elevation in histopathological cell damage in the infected group (Group II) compared with the control group. The vaccine and challenged after vaccination group (vaccine + Bacteria), showed great improvement in oxidative biomarkers (LPO) and an increase in antioxidants biomarkers (GSH, SOD, GST, DPPH, ABTS, GR and GPx), Also the inflammation and histopathological examination. The newly synthesized vaccine improved the resistance of Oreochromis niloticus and can be used as a preventive therapy agent for pathogenic bacteria S. pyogenes.

MRI-Guided Tumor Therapy Based on Synergy of Ferroptosis, Immunosuppression Reversal and Disulfidptosis

Triple negative breast cancer (TNBC) cells have a high demand for oxygen and glucose to fuel their growth and spread, shaping the tumor microenvironment (TME) that can lead to a weakened immune system by hypoxia and increased risk of metastasis. To disrupt this vicious circle and improve cancer therapeutic efficacy, a strategy is proposed with the synergy of ferroptosis, immunosuppression reversal and disulfidptosis. An intelligent nanomedicine GOx-IA@HMON@IO is successfully developed to realize this strategy. The Fe release behaviors indicate the glutathione (GSH)-responsive degradation of HMON. The results of titanium sulfate assay, electron spin resonance (ESR) spectra, 5,5'-Dithiobis-(2-nitrobenzoic acid (DTNB) assay and T1-weighted magnetic resonance imaging (MRI) demonstrate the mechanism of the intelligent iron atom (IA)-based cascade reactions for GOx-IA@HMON@IO, generating robust reactive oxygen species (ROS). The results on cells and mice reinforce the synergistic mechanisms of ferroptosis, immunosuppression reversal and disulfidptosis triggered by the GOx-IA@HMON@IO with the following steps: 1) GSH peroxidase 4 (GPX4) depletion by disulfidptosis; 2) IA-based cascade reactions; 3) tumor hypoxia reversal; 4) immunosuppression reversal; 5) GPX4 depletion by immunotherapy. Based on the synergistic mechanisms of ferroptosis, immunosuppression reversal and disulfidptosis, the intelligent nanomedicine GOx-IA@HMON@IO can be used for MRI-guided tumor therapy with excellent biocompatibility and safety.

Vitamin E alleviates chlorpyrifos induced glutathione depletion, lipid peroxidation and iron accumulation to inhibit ferroptosis in hepatocytes and mitigate toxicity in zebrafish

Organophosphates, a widely used group of pesticides, can cause severe toxicity in human beings and other non-target organisms. Liver, being the primary site for xenobiotic metabolism, is extremely vulnerable to xenobiotic-induced toxicity. Considering the numerous vital functions performed by the liver, including xenobiotic detoxification, protecting this organ from the ubiquitous pesticides in our food and environment is essential for maintaining homeostasis. In this study, we have investigated the impact of the organophosphate pesticide, Chlorpyrifos (CPF), on zebrafish liver at a concentration (300 μg/L) which is environmentally realistic. We have also demonstrated the role of dietary supplementation of α-tocopherol or Vitamin E (Vit E) (500 mg/kg feed) in mitigating pesticide-induced liver toxicity. Mechanistically, we showed that Vit E resulted in significant elevation of the Nrf2 and its downstream antioxidant enzyme activities and gene expressions, especially that of GST and GPx, resulting in reduction of CPF-induced intracellular lipid ROS and hepatic LPO. Further interrogation, such as analysis of GSH: GSSG ratio, intracellular iron concentration, iron metabolizing genes, mitochondrial dysfunction etc. revealed that CPF induces ferroptosis which can be reversed by Vit E supplementation. Ultimately, reduced concentration of CPF in zebrafish serum and flesh highlighted the role of Vit E in ameliorating CPF toxicity.

Alpha-tocopherol inhibits ferroptosis and promotes neural function recovery in rats with spinal cord injury via downregulating Alox15

Spinal cord injury (SCI) is a type of central nervous system (CNS) injury in which ferroptosis is becoming a promising target for treatment. Alpha-tocopherol (Vitamin E, Vit E) is a compound with anti-ferroptosis activity. The mechanism of alpha-tocopherol in regulating ferroptosis after SCI has not been deeply studied. In this study, rats with SCI were treated by Alpha-tocopherol based on bioinformatic analysis and molecular docking prediction. Behavioral tests and histological findings showed that Alpha-tocopherol promoted neural function recovery and tissue repairment in rats with SCI. Subsequently, regulatory effects of Alpha-tocopherol on Alox15 and ferroptosis were detected and then localized by immunofluorescence. In vitro, alpha-tocopherol improved the ROS accumulation, iron overload, lipid peroxidation and mitochondrial dysfunction. The effects of Alpha-tocopherol on the expression of Alox15, Ptgs2 and 4Hne were validated in vitro. Finally, the inhibitory effects of Alpha-tocopherol on Alox15 and ferroptosis were weakened by the mutation of 87th residue of Alox15. In summary, alpha-tocopherol could alleviate SCI-induced ferroptosis by downregulating Alox15 to promote neural function recovery in rats with SCI. Findings in this study could help further our understanding on SCI-induced ferroptosis and provide a novel insight for treating SCI.

Biochemical Changes in Anterior Chamber of the Eye in Diabetic Patients-A Review

This article aims to provide a comprehensive review of the biochemical changes observed in the anterior chamber of the eye in diabetic patients. The increased levels of inflammatory markers, alterations in antioxidant defense mechanisms, and elevated levels of advanced glycation end products (AGEs) in the aqueous humor (AH) are explored. Additionally, the impact of these biochemical changes on diabetic retinopathy progression, increased intraocular pressure, and cataract formation is discussed. Furthermore, the diagnostic and therapeutic implications of these findings are presented. This study explores potential biomarkers for detecting diabetic eye disease at an early stage and monitoring its progression. An investigation of the targeting of inflammatory and angiogenic pathways as a potential treatment approach and the role of antioxidant agents in managing these biochemical changes is performed.

Distribution and Utilization of Vitamin E in Different Organs of Wild Bats from Different Food Groups

In this work, we examined the levels of vitamin E in the heart, liver, and kidneys of four species of adult male bats with distinct feeding habits. Our results indicate consistent vitamin E levels in the heart across all four bat species, suggesting the presence of regulatory mechanisms. Additionally, the liver displayed notably higher vitamin E levels in nectarivorous and frugivorous bats, while hematophagous bats exhibited lower levels, indicating a link between dietary intake and liver vitamin E levels. Furthermore, correlation analysis provided additional insights into the relationships between vitamin E and key antioxidant parameters in the livers of bats. On the other hand, no correlation was observed between vitamin E and key antioxidant parameters in the heart. Intriguingly, vitamin E was not detected in the kidneys, likely due to physiological factors and the prioritization of vitamin E mobilization in the heart, where it serves critical physiological functions. This unexpected absence of vitamin E in bat kidneys highlights the unique metabolic demands and prioritization of vitamin mobilization in wild animals like bats, compared to conventional animal models. These findings provide insight into the intricate distribution and utilization of vitamin E in bats, emphasizing the influence of dietary intake and metabolic adaptations on vitamin E levels in different organs.

A STING pathway-activatable contrast agent for MRI-guided tumor immunoferroptosis synergistic therapy

The immunotherapy efficiency of stimulator of interferon genes (STING)-activatable drugs (e.g., 7-ethyl-10-hydroxycamptothecin, SN38) is limited by their non-specificity to tumor cells and the slow excretion of the DNA-containing exosomes from the treated cancer cells. The efficacy of tumor ferroptosis therapy is always limited by the elimination of lipid peroxides (LPO) by the pathways of glutathione peroxidase 4 (GPX4), dihydroorotate dehydrogenase (DHODH) and ferroptosis suppressor protein 1(FSP1). To solve these problems, in this study, we developed a STING pathway-activatable contrast agent (i.e., FeGd-HN@TA-Fe2+-SN38 nanoparticles) for magnetic resonance imaging (MRI)-guided tumor immunoferroptosis synergistic therapy. The remarkable in vivo MRI performance of FeGd-HN@TA-Fe2+-SN38 is attributed to its high accumulation at tumor location, the high relaxivities of FeGd-HN core, and the pH-sensitive TA-Fe2+-SN38 layer. The effectiveness and biosafety of the immunoferroptosis synergistic therapy induced by FeGd-HN@TA-Fe2+-SN38 are demonstrated by the in vivo investigations on the 4T1 tumor-bearing mice. The mechanisms of in vivo immunoferroptosis synergistic therapy by FeGd-HN@TA-Fe2+-SN38 are demonstrated by measurements of in vivo ROS, LPO, GPX4 and SLC7A11 levels, the intratumor matured DCs and CD8+ T cells, the protein expresion of STING and IRF-3, and the secretion of IFN-β and IFN-γ.

Doping Engineering to Modulate Lattice and Electronic Structure for Enhanced Piezocatalytic Therapy and Ferroptosis

Piezocatalytic therapy, which generates reactive oxygen species (ROS) under mechanical force, has garnered extensive attention for its use in cancer therapy owing to its deep tissue penetration depth and less O2 -dependence. However, the piezocatalytic therapeutic efficiency is limited owing to the poor piezoresponse, low separation of electron-hole pairs, and complicated tumor microenvironment (TME). Herein, a biodegradable, porous Mn-doped ZnO (Mn-ZnO) nanocluster with enhanced piezoelectric effect is constructed via doping engineering. Mn-doping not only induces lattice distortion to increase polarization but also creates rich oxygen vacancies (OV ) for suppressing the recombination of electron-hole pairs, leading to high-efficiency generation of ROS under ultrasound irradiation. Moreover, Mn-doped ZnO shows TME-responsive multienzyme-mimicking activity and glutathione (GSH) depletion ability owing to the mixed valence of Mn (II/III), further aggravating oxidative stress. Density functional theory calculations show that Mn-doping can improve the piezocatalytic performance and enzyme activity of Mn-ZnO due to the presence of OV . Benefiting from the boosting of ROS generation and GSH depletion ability, Mn-ZnO can significantly accelerate the accumulation of lipid peroxide and inactivate glutathione peroxidase 4 (GPX4) to induce ferroptosis. The work may provide new guidance for exploring novel piezoelectric sonosensitizers for tumor therapy.

Redox Regulation in Age-Related Cataracts: Roles for Glutathione, Vitamin C, and the NRF2 Signaling Pathway

Age is the biggest risk factor for cataracts, and aberrant oxidative modifications are correlated with age-related cataracts, suggesting that proper redox regulation is important for lens clarity. The lens has very high levels of antioxidants, including ascorbate and glutathione that aid in keeping the lens clear, at least in young animals and humans. We summarize current functional and genetic data supporting the hypothesis that impaired regulation of oxidative stress leads to redox dysregulation and cataract. We will focus on the essential endogenous antioxidant glutathione and the exogenous antioxidant vitamin C/ascorbate. Additionally, gene expression in response to oxidative stress is regulated in part by the transcription factor NRF2 (nuclear factor erythroid 2-related factor 2 [NFE2L2]), thus we will summarize our data regarding cataracts in Nrf2-/- mice. In this work, we discuss the function and integration of these capacities with the objective of maintaining lens clarity.

Pharmacotherapy and Nutritional Supplements for Neovascular Eye Diseases

In this review, we aim to provide an overview of the recent findings about the treatment of neovascular retinal diseases. The use of conventional drugs and nutraceuticals endowed with antioxidant and anti-inflammatory properties that may support conventional therapies will be considered, with the final aim of achieving risk reduction (prevention) and outcome improvement (cooperation between treatments) of such sight-threatening proliferative retinopathies. For this purpose, we consider a medicinal product one that contains well-defined compound(s) with proven pharmacological and therapeutic effects, usually given for the treatment of full-blown diseases. Rarely are prescription drugs given for preventive purposes. A dietary supplement refers to a compound (often an extract or a mixture) used in the prevention or co-adjuvant treatment of a given pathology. However, it must be kept in mind that drug-supplement interactions may exist and might affect the efficacy of certain drug treatments. Moreover, the distinction between medicinal products and dietary supplements is not always straightforward. For instance, melatonin is formulated as a medicinal product for the treatment of sleep and behavioral problems; at low doses (usually below 1 mg), it is considered a nutraceutical, while at higher doses, it is sold as a psychotropic drug. Despite their lower status with respect to drugs, increasing evidence supports the notion of the beneficial effects of dietary supplements on proliferative retinopathies, a major cause of vision loss in the elderly. Therefore, we believe that, on a patient-by-patient basis, the administration of nutraceuticals, either alone or in association, could benefit many patients, delaying the progression of their disease and likely improving the efficacy of pharmaceutical drugs.

Toxicity enhancement of nano titanium dioxide to Brachionus calyciflorus (Rotifera) under simulated sunlight and the underlying mechanisms

Nano titanium dioxide (nTiO₂) generally shows low toxicity to organisms under light-emitting diode (LED) light. However, nTiO₂ can induce production of reactive oxygen species (ROS) under ultraviolet (UV) light due to its photocatalytic activity. Therefore, it is reasonable to expect the enhancement of nTiO₂ toxicity under sunlight. To test this hypothesis, we compared the toxicity of nTiO₂ to Brachionus calyciflorus under simulated sunlight and LED light. The results showed that the 24 h-LC₅₀ of nTiO₂ to B. calyciflorus under LED light and simulated sunlight were 24.32 (95% CI: 14.54-46.81 mg/L) and 10.44 mg/L (95% CI: 6.74-17.09 mg/L), respectively. Compared with the blank control, treatments with nTiO₂ significantly affected life-table demographic parameters, population growth parameters and swimming linear speed under both simulated sunlight and LED light. However, life expectancy, net reproductive rate, average lifespan, maximal population density, and swimming linear speed in the treatments of nTiO₂ at 0.1, 1, and/or 10 mg/L showed markedly lower values under simulated sunlight than those under LED light, suggesting that simulated sunlight could enhance the toxicity of nTiO₂. In addition, markedly higher catalase (CAT) activity and malondialdehyde (MDA) content but lower glutathione (GSH) content were observed in treatment with 10 mg/L nTiO₂ under simulated sunlight than that under LED light. The results showed that compared with LED light, simulated sunlight significantly induced more oxidative stress in the presence of nTiO₂, and the ROS production was mainly localized to the corona and digestive tract of rotifers by confocal laser scanning microscope. Exposure to 10-50 μM of vitamin C, that is an effective ROS scavenger, could rescue the swimming linear speed of rotifers to the normal level in the blank control. These results suggested that oxidative damages on cell membrane might be the vital mechanism underlying the toxicity enhancement of nTiO₂ to rotifers under simulated sunlight. Thus, the previous publications under LED light may underestimate the real toxicity and environmental risk of nTiO₂ in natural conditions.

Oxidative Stress in the Anterior Ocular Diseases: Diagnostic and Treatment

The eye is a metabolically active structure, constantly exposed to solar radiations making its structure vulnerable to the high burden of reactive oxygen species (ROS), presenting many molecular interactions. The biomolecular cascade modification is caused especially in diseases of the ocular surface, cornea, conjunctiva, uvea, and lens. In fact, the injury in the anterior segment of the eye takes its origin from the perturbation of the pro-oxidant/antioxidant balance and leads to increased oxidative damage, especially when the first line of antioxidant defence weakens with age. Furthermore, oxidative stress is related to mitochondrial dysfunction, DNA damage, lipid peroxidation, protein modification, apoptosis, and inflammation, which are involved in anterior ocular disease progression such as dry eye, keratoconus, uveitis, and cataract. The different pathologies are interconnected through various mechanisms such as inflammation, oxidative stress making the diagnostics more relevant in early stages. The end point of the molecular pathway is the release of different antioxidant biomarkers offering the potential of predictive diagnostics of the pathology. In this review, we have analysed the oxidative stress and inflammatory processes in the front of the eye to provide a better understanding of the pathomechanism, the importance of biomarkers for the diagnosis of eye diseases, and the recent treatment of anterior ocular diseases.

Oxidative stress coping capacity (OSC) value: Development and validation of an in vitro measurement method for blood plasma using electron paramagnetic resonance spectroscopy (EPR) and vitamin C

Oxidative stress as a driver of disease is reinforcing the trend towards supplementation with antioxidants. While antioxidants positively influence the redox status when applied at physiological doses, higher concentrations may have pro-oxidative effects. Precise assessment methods for testing the supply of antioxidants are lacking. Using in-situ-irradiation as stressor and electron paramagnetic resonance (EPR) spectroscopy as readout system for formed radicals, a stress response assessment method was developed, using protein solutions and plasma samples from transfusion medicine. The method was validated in a double-blind placebo-controlled in vivo cross-over pilot study in blood plasma samples of individuals before and after vitamin C supplementation. Reference measurements were performed for the exogenous antioxidants β-carotene and vitamin C, and glutathione as an endogenous representative. Malondialdehyde was studied for oxidative stress indication. Protein solutions without antioxidants showed a linear increase in radical concentration during irradiation. The in-vitro-addition of vitamin C or plasma samples from subjects displayed two slopes (m₁, m₂) for radical production, whereby m₁ represented the amount of antioxidants and proteins, m₂ only the protein content. These two slopes in combination with the intervening transition area (T) were used to calculate the oxidative stress coping capacity (OSC), which correlated positively with vitamin C concentration in blood plasma, while oxidative stress biomarkers showed only fluctuations within their reference ranges. Furthermore, a selective radical quenching mechanism for vitamin C was observed: the proportion of reactive oxygen species (ROS) in the plasma samples was degraded in dependence to the vitamin C concentration ingested. The proportion of lipid oxygen species (LOS) remained stable while the ascorbyl radical increased with higher vitamin C intake. OSC may represent a sensitive method to detect treatment effects on the redox status in vivo in future validation and treatment studies, and potentially in clinical routine.

Effect of Dried Apple Pomace (DAP) as a Feed Additive on Antioxidant System in the Rumen Fluid

The study aimed to evaluate the effect of dried apple pomace (DAP) as a feed additive on the enzymatic activity and non-enzymatic compounds belonging to the antioxidant system in cattle rumen fluid. The experiment included 4 Polish Holstein−Friesian cannulated dairy cows and lasted 52 days. The control group was fed with the standard diet, while in the experimental group, 6% of the feedstuff was replaced by dried apple pomace. After the feeding period, ruminal fluid was collected. The spectrophotometric technique for the activity of lysosomal enzymes, the content of vitamin C, polyphenols, and the potential to scavenge the free DPPH radical was used. The enzyme immunoassay tests (ELISA) were used to establish the activity of antioxidants enzymes and MDA. Among the rumen aminopeptidases, a significant reduction (p < 0.01) from 164.00 to 142.00 was observed for leucyl-aminopeptidase. The activity of glycosidases was decreased for HEX (from 231.00 to 194.00) and β-Glu (from 1294.00 to 1136.00), while a significant statistically increase was noticed for BGRD (from 31.10 to 42.40), α-Glu (from 245.00 to 327.00), and MAN (from 29.70 to 36.70). Furthermore, the activity of catalase and GSH (p < 0.01) was inhibited. In turn, the level of vitamin C (from 22.90 to 24.10) and MDA (from 0.36 to 0.45) was statistically higher (p < 0.01). The most positive correlations were observed between AlaAP and LeuAP (r = 0.897) in the aminopeptidases group and between β-Gal and MAN (r = 0.880) in the glycosidases group. Furthermore, one of the most significant correlations were perceived between SOD and AlaAP (r = 0.505) and AcP (r = 0.450). The most negative correlation was noticed between α-Gal and DPPH (r = −0.533) based on these observations. Apple pomace as a feed additive has an influence on lysosomal degradation processes and modifies oxidation−reduction potential in the rumen fluid. Polyphenols and other low-weight antioxidant compounds are sufficient to maintain redox balance in the rumen.

The Effect of Diet and Lifestyle on the Course of Diabetic Retinopathy-A Review of the Literature

Diabetes is a major social problem. As shown by epidemiological studies, the world incidence of diabetes is increasing and so is the number of people suffering from its complications. Therefore, it is important to determine possible preventive tools. In the prevention of diabetic retinopathy, it is essential to control glycemia, lipid profile and blood pressure. This can be done not only by pharmacological treatment, but first of all by promoting a healthy lifestyle, changing dietary habits and increasing physical activity. In our work, we present a review of the literature to show that physical exercise and an adequate diet can significantly reduce the risk of diabetes and diabetic retinopathy.

The Associations of Plasma Carotenoids and Vitamins With Risk of Age-Related Macular Degeneration: Results From a Matched Case-Control Study in China and Meta-Analysis

Background and Purpose

Data from studies support a beneficial effect of carotenoids and vitamins on an age-related macular degeneration (AMD) risk. However, studies on the relations between blood levels of these nutrients and AMD are limited and provided conflicting results. The objective of this case-control study and meta-analysis was to examine whether the blood concentrations of carotenoids and vitamins were associated with the risk of AMD.

Methods

A total of 164 cases of AMD and an equal number of controls are individually matched according to age and gender among the participants, who provided blood samples in the Xi'an Eye Study. Plasma carotenoids and vitamins were measured using reversed-phase high-performance liquid chromatography. Bonferroni-corrected covariate-adjusted conditional logistic regression were used to estimate AMD risk by category of these nutrients in the multivariable-adjusted model. Nine studies were identified for the meta-analysis and calculated pooled risk estimates by means of a random-effects model.

Results

Plasma concentrations of examined carotenoids and vitamins were significantly lower in patients with AMD than those in controls. Plasma concentrations of examined carotenoids and vitamins were significantly lower in patients with AMD than those in controls. After a multivariate adjustment for body mass index, blood cholesterol, and other lifestyle risk factors, higher lutein/zeaxanthin content in plasma was significantly associated with a decreased risk of AMD, and the odds ratio (OR) comparing the top and bottom tertiles was 0.21 (95% CI: 0.05, 0.84; P_trend = 0.024). Associations for β-carotenes (OR: 0.11; 95% CI: 0.02, 0.50; P_trend < 0.001), and β-cryptoxanthin (OR: 0.08, 95% CI: 0.02, 0.39; P_trend < 0.001) were similar to that for lutein/zeaxanthin. Inverse associations were also observed for a higher level of retinol (OR: 0.14, 95% CI: 0.03, 0.61; P_trend = 0.006) and α-tocopherol (OR: 0.25, 95% CI: 0.06, 0.98; P_trend = 0.006). In the meta-analysis, a protective effect was detected for AMD among the participants with high blood lutein/zeaxanthin level (OR: 0.53, 95% CI: 0.40, 0.72, P < 0.001), compared to those with low level. Similar inverse associations were seen for β-carotene (OR: 0.48, 95% CI: 0.28, 0.84, P = 0.010), β-cryptoxanthin (OR: 0.48, 95% CI: 0.23, 1, P = 0.049), lycopene (OR: 0.70, 95% CI: 0.54, 0.90, P = 0.006) and α-tocopherol (OR: 0.50, 95% CI: 0.31, 0.81, P = 0.005).

Conclusions

Results of the case-control study were consistent with findings from the meta-analysis, indicating that higher concentrations of carotenoids and vitamins were inversely associated with the AMD risk. Our finding supports the current notion that these nutrients are likely to affect the development of AMD and may help to refine the strategies for the prevention of age-related eye diseases.

GSH Levels Serve As a Biological Redox Switch Regulating Sulforaphane-Induced Cell Fate in Human Lens Cells

Purpose

Sulforaphane (SFN) is a therapeutic phytochemical agent for many health conditions. SFN-induced cytotoxicity is shown to have promise in preventing posterior capsule opacification (PCO). In the current study, we aimed to elucidate key processes and mechanisms linking SFN treatment to lens cell death.

Methods

The human lens epithelial cell line FHL124 and central anterior epithelium were used as experimental models. Cell death was assessed by microscopic observation and cell damage/viability assays. Gene or protein levels were assessed by TaqMan RT-PCR or immunoblotting. Mitochondrial networks and DNA damage were assessed by immunofluorescence. Mitochondrial membrane potential, activating transcription factor 6 (ATF6) activity, ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), and glutathione reductase (GR) activity were measured using different light reporter assays. SFN metabolites were analyzed by LC-MS/MS.

Results

Treatment with N-acetylcysteine (NAC), a reactive oxygen species scavenger, prevented SFN-induced cell death in both models. NAC also significantly protected FHL124 cells from SFN-induced mitochondrial dysfunctions, endoplasmic reticulum stress (ERS), DNA damage and autophagy. SFN significantly depleted GSH, the major antioxidant in the eye, and reduced GR activity, despite doubling its protein levels. The most abundant SFN conjugate detected in lens cells following SFN application was SFN-GSH. The addition of GSH protected lens cells from all SFN-induced cellular events.

Conclusions

SFN depletes GSH levels in lens cells through conjugation and inhibition of GR activity. This leads to increased reactive oxygen species and oxidative stress that trigger mitochondrial dysfunction, ERS, autophagy, and DNA damage, leading to cell death. In summary, the work presented provides a mechanistic understanding to support the therapeutic application of SFN for PCO and other disorders.

Protective Action of Hydrogen Sulfide-Releasing Compounds against Oxidative Stress-Induced Cataract Formation in Cultured Bovine Lenses

PURPOSE

The gaseous signalling molecule, hydrogen sulfide (H₂S) has antioxidant, anti-inflammatory and anti-apoptotic properties. Since oxidative stress has been implicated in the pathogenesis of cataracts and lenticular hydrogen peroxide (H₂O₂) is elevated in some cataract patients, the present study investigated the ability of H₂S-releasing compounds to prevent H₂O₂-induced cataract formation in cultured bovine lenses.

METHODS

Lenses were cultured in either Dulbecco's Modified Eagle Medium (DMEM; control); H₂O₂ (50 mM); ascorbic acid (AA; 3 mM) (positive control); and the H₂S-releasing compounds (diallyl trisulfide [DATS] or GYY4137) in the presence of H₂O₂ (50 mM). Lens opacity was determined using a plate reader to measure transmittance. Lens glutathione content (GSH), superoxide dismutase (SOD) activity and lactate dehydrogenase (LDH) cytotoxicity were assessed before and after treatment with the H₂S-releasing compounds.

RESULTS

Both DATS (10^-7M - 10^-4M) and GYY4137 (10^-7M - 10^-4M) significantly (p < .001) attenuated H₂O₂ (50 mM)-induced loss in transmittance, with DATS (10^-4M) and GYY4137 (10^-7M) achieving a maximal reversal of opacity by 56.86 ± 0.01% (n = 6) and 8.39 ± 0.11% (n = 6) after 120 hours, respectively. These observations were corroborated by photographic evaluation, where DATS (10^-5M - 10^-4M) and GYY4137 (10^-7M - 10^-5M)-treated lenses had relatively clear grids after 120 hours, compared to H₂O₂ (50 mM)-treated lenses. The H₂O₂ (50 mM)-induced decline in total GSH content and total SOD activity were significantly (p < .001; n = 5) reversed by DATS (10^-4M) and GYY4137 (10^-7M). After 24 hours, DATS (10^-4M) and GYY4137 (10^-7M) significantly (p < .001; n = 4) reduced cytotoxicity of primary bovine lens epithelial cells by 33.88 ± 4.59% and 36.19 ± 10.53%, respectively.

CONCLUSION

Both H₂S-releasing compounds protected cultured bovine lenses against oxidative stress-induced cataract formation. The slow-releasing H₂S compound, GYY4137 was more potent than DATS in restoring lenticular total GSH content and total SOD activity along with reducing H₂O₂ (50 mM)-induced cytotoxicity.

Hallmarks of lens aging and cataractogenesis

Lens homeostasis and transparency are dependent on the function and intercellular communication of its epithelia. While the lens epithelium is uniquely equipped with functional repair systems to withstand reactive oxygen species (ROS)-mediated oxidative insult, ROS are not necessarily detrimental to lens cells. Lens aging, and the onset of pathogenesis leading to cataract share an underlying theme; a progressive breakdown of oxidative stress repair systems driving a pro-oxidant shift in the intracellular environment, with cumulative ROS-induced damage to lens cell biomolecules leading to cellular dysfunction and pathology. Here we provide an overview of our current understanding of the sources and essential functions of lens ROS, antioxidative defenses, and changes in the major regulatory systems that serve to maintain the finely tuned balance of oxidative signaling vs. oxidative stress in lens cells. Age-related breakdown of these redox homeostasis systems in the lens leads to the onset of cataractogenesis. We propose eight candidate hallmarks that represent common denominators of aging and cataractogenesis in the mammalian lens: oxidative stress, altered cell signaling, loss of proteostasis, mitochondrial dysfunction, dysregulated ion homeostasis, cell senescence, genomic instability and intrinsic apoptotic cell death.

Prevention of Teratogenesis in Pregnancies of Obese Rats by Vitamin E Supplementation

Congenital malformations are a common adverse outcome in pregnancies complicated by pregestational obesity, although the underlying mechanisms are still unrevealed. Our aim was to study the effect of oxidative stress in obesity-induced teratogenesis. Wistar rats were fed a high-fat diet for 13 weeks, with (OE group) or without (O group) vitamin E supplementation. Then, rats were mated and sacrificed at day 11.5 of gestation. Embryos from O dams presented a 25.9 ± 3.5% rate of malformations (vs. 8.7 ± 3.4% in C rats), which was reduced in the OE group (11.5 ± 2.3%). Pregestational obesity induced hepatic protein and DNA oxidation and a decline in antioxidant enzymes. Importantly, glutathione content was also decreased, limiting the availability of this antioxidant in the embryos. Vitamin E supplementation efficiently maintained glutathione levels in the obese mothers, which could be used in their embryos to prevent oxidation-induced malformations. To test the effect of decreasing glutathione levels alone in a cell culture model of neuroepithelium, murine embryonic stem cells (ESC) were induced to form neuronal precursors and glutathione synthesis was inhibited with the gamma–glutamylcysteine synthesis inhibitor, buthionine sulfoximine (BSO). BSO inhibited the expression of Pax3, a gene required for neural tube closure that is also inhibited by oxidative stress. Taken together, our data indicate that obesity causes malformations through the depletion of maternal glutathione, thereby decreasing glutathione-dependent free radical scavenging in embryos, which can be prevented by vitamin E supplementation.

Antioxidant Activity of Hemp (Cannabis sativa L.) Seed Oil in Drosophila melanogaster Larvae under Non-Stress and H2O2-Induced Oxidative Stress Conditions

The oil extracted from hemp seeds has significant nutritional and biological properties due to the unique composition of polyunsaturated fatty acids and various antioxidant compounds. The potential of this oil for the prevention of oxidative stress and for the treatment of oxidative-stress-induced ailments is of increasing interest. Most studies of hemp seed oil were conducted in-vitro, meaning we lack information about effects and activity in vivo. In the present study, we evaluated the hypothesis that hemp seed oil at different concentrations improves the oxidative state of D. melanogaster, under non-stress as well as hydrogen-peroxide-induced stress. We analyzed the effects of hemp seed oil on oxidative stress markers and on the life cycle of D.melanogaster under non-stress and hydrogen-peroxide-induced stress conditions. D.melanogaster larvae were exposed to hemp seed oil concentrations ranging from 12.5 to 125 μL/mL. The results revealed that under non-stress conditions, oil concentrations up to 62.5 µL/mL did not induce negative effects on the life cycle of D. melanogaster and maintained the redox status of the larval cells at similar levels to the control level. Under oxidative stress conditions, biochemical parameters were significantly affected and only two oil concentrations, 18.7 and 31.2 µL/mL, provided protection against hydrogen peroxide stress effects. A higher oil concentration (125 μL/mL) exerted negative effects on the oxidative status and increased larval mortality. The tested oil was characterized chemically by NMR, transesterification, and silylation, followed by GC-MS analyses, and was shown to contain polyunsaturated fatty acid triglycerides and low levels of tocopherols. The high levels of linoleic and linolenic acids in the oil are suggested to be responsible for the observed in vivo antioxidant effects. Taken together, the results show that hemp seed oil is effective for reducing oxidative stress at the cellular level, thus supporting the hypothesis. The obtained results point to the potential of hemp seed oil for the prevention and treatment of conditions caused by the action of reactive oxygen species.

Vitamin C and Cardiovascular Disease: An Update

The potential beneficial effects of the antioxidant properties of vitamin C have been investigated in a number of pathological conditions. In this review, we assess both clinical and preclinical studies evaluating the role of vitamin C in cardiac and vascular disorders, including coronary heart disease, heart failure, hypertension, and cerebrovascular diseases. Pitfalls and controversies in investigations on vitamin C and cardiovascular disorders are also discussed.

Ascorbic acid interaction with phytol: a modulatory effects on the anti-pyretic activity of paracetamol in Swiss albino mice

Background

Antioxidants have protective capacity, and can be used combinedly with other substances. Both, ascorbic acid (AA) and phytol (PHY) have many important biological activities, including antioxidant, anti-inflammatory, and organ protective activity. Recently, PHY has been found to exert an anti-pyretic effect in a mouse model. This study aims to evaluate the combined effects of AA and/or PHY with paracetamol (PARA) in Brewer’s yeast-induced fever mice model.

Methods

AA (125 mg/kg) and/or PHY (200 mg/kg) were orally co-treated with the PARA (100 mg/kg, p.o.) in Brewer’s yeast-induced fever Swiss mice. Data were analyzed by using GraphPadPrism software (version: 6.0), considering p < 0.05 at 95% confidence interval, and using one-way analysis of variance (ANOVA) through time, followed by Dunnett’s post hoc multiple comparison test.

Results

PARA alone and with PHY and/or AA significantly (p < 0.05) reduced rectal temperature at 1st h of observation. PHY reduced rectal temperature at 2nd h, then maintained basal temperature over the observation period (4 h). AA showed an insignificant anti-pyretic effect in experimental animals. However, in combination groups, AA (i.e., with PHY or PARA) did not found to interfere the PHY and PARA mediated reduction of rectal temperature in the animals. Furthermore, AA when co-treated with the PARA + PHY, it caused a slight hypothermic temperature at 1st h, which was then started to restablish from 2nd to 3rd h, and normalized at 4th h.

Conclusion

Taken together, AA did not interfere anti-pyretic effects of PARA and PHY, suggesting its possible use as a combination substance.

Oxidative stress and diabetic retinopathy: Molecular mechanisms, pathogenetic role and therapeutic implications

Oxidative stress, a cytopathic outcome of excessive generation of ROS and the repression of antioxidant defense system for ROS elimination, is involved in the pathogenesis of multiple diseases, including diabetes and its complications. Retinopathy, a microvascular complication of diabetes, is the primary cause of acquired blindness in diabetic patients. Oxidative stress has been verified as one critical contributor to the pathogenesis of diabetic retinopathy. Oxidative stress can both contribute to and result from the metabolic abnormalities induced by hyperglycemia, mainly including the increased flux of the polyol pathway and hexosamine pathway, the hyper-activation of protein kinase C (PKC) isoforms, and the accumulation of advanced glycation end products (AGEs). Moreover, the repression of the antioxidant defense system by hyperglycemia-mediated epigenetic modification also leads to the imbalance between the scavenging and production of ROS. Excessive accumulation of ROS induces mitochondrial damage, cellular apoptosis, inflammation, lipid peroxidation, and structural and functional alterations in retina. Therefore, it is important to understand and elucidate the oxidative stress-related mechanisms underlying the progress of diabetic retinopathy. In addition, the abnormalities correlated with oxidative stress provide multiple potential therapeutic targets to develop safe and effective treatments for diabetic retinopathy. Here, we also summarized the main antioxidant therapeutic strategies to control this disease.

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Oxidative stress can both contribute to and result from hyperglycemia-induced metabolic abnormalities in retina.

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Genes important in regulation of ROS are epigenetically modified, increasing ROS accumulation in retina.

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Oxidative stress is closely associated with the pathological changes in the progress of diabetic retinopathy.

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Antioxidants ameliorate retinopathy through targeting multiple steps of oxidative stress.

Vitamin C and the Lens: New Insights into Delaying the Onset of Cataract

Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic population, the burden of cataracts will grow. Cataract surgery is an effective way to restore vision; however, alternatives to cataract surgery are required to reduce the looming cataract epidemic. Since it is well established that oxidative damage plays a major role in the etiology of cataracts, antioxidants have been promoted as therapies to delay and/or prevent cataracts. However, many antioxidant interventions including vitamin C have produced mixed results as anti-cataract therapies. Progress has been made towards our understanding of lens physiology and the mechanisms involved in the delivery and uptake of antioxidants to the lens which may guide future studies aimed at addressing some of the inconsistencies seen in previous animal and human studies. Of interest is the potential for vitamin C based supplements in delaying the onset of cataracts post vitrectomy which occurs in up to 80% of patients within two years. These targeted approaches are required to reduce the burden of cataract on hospitals and improve the quality of life of our aging and diabetic population.

Oxidative Stress in Parkinson's Disease: Potential Benefits of Antioxidant Supplementation

Parkinson's disease (PD) occurs in approximately 1% of the population over 65 years of age and has become increasingly more common with advances in age. The number of individuals older than 60 years has been increasing in modern societies, as well as life expectancy in developing countries; therefore, PD may pose an impact on the economic, social, and health structures of these countries. Oxidative stress is highlighted as an important factor in the genesis of PD, involving several enzymes and signaling molecules in the underlying mechanisms of the disease. This review presents updated data on the involvement of oxidative stress in the disease, as well as the use of antioxidant supplements in its therapy.

Importance of the Use of Oxidative Stress Biomarkers and Inflammatory Profile in Aqueous and Vitreous Humor in Diabetic Retinopathy

Diabetic retinopathy is one of the leading causes of visual impairment and morbidity worldwide, being the number one cause of blindness in people between 27 and 75 years old. It is estimated that ~191 million people will be diagnosed with this microvascular complication by 2030. Its pathogenesis is due to alterations in the retinal microvasculature as a result of a high concentration of glucose in the blood for a long time which generates numerous molecular changes like oxidative stress. Therefore, this narrative review aims to approach various biomarkers associated with the development of diabetic retinopathy. Focusing on the molecules showing promise as detection tools, among them we consider markers of oxidative stress (TAC, LPO, MDA, 4-HNE, SOD, GPx, and catalase), inflammation (IL-6, IL-1ß, IL-8, IL-10, IL-17A, TNF-α, and MMPs), apoptosis (NF-kB, cyt-c, and caspases), and recently those that have to do with epigenetic modifications, their measurement in different biological matrices obtained from the eye, including importance, obtaining process, handling, and storage of these matrices in order to have the ability to detect the disease in its early stages.

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

Exposure to sunlight and contact with atmospheric oxygen makes the eye particularly susceptible to oxidative stress, which can potentially produce cellular damage. In physiological conditions, there are several antioxidant defense mechanisms within the eye. Glutathione (GSH) is the most important antioxidant in the eye; GSH deficit has been linked to several ocular pathologies. The aim of this study was to explore the potential for newly developed formulations allowing controlled delivery of antioxidants such as GSH and vitamin C (Vit C) directly to the eye. We have investigated the stability of antioxidants in aqueous solution and assessed ex-vivo the diffusion of GSH through two ocular membranes, namely cornea and sclera, either in solution or included in a semisolid insert. We have also carried out the hen’s egg-chlorioallantoic membrane test (HET-CAM) to evaluate the ocular irritancy of the different antioxidant solutions. Our results showed that GSH is stable for up to 30 days at 4 °C in darkness and it is not an irritant to the eye. The diffusion studies revealed that the manufactured formulation, a semisolid insert containing GSH, could deliver this tripeptide directly to the eye in a sustained manner.

Glutathione Improves the Antioxidant Activity of Vitamin C in Human Lens and Retinal Epithelial Cells: Implications for Vitreous Substitutes

PURPOSE

Tissues in the eye are particularly susceptible to oxidative damage due to light exposure. While vitamin C (ascorbic acid) has been noted as a vital antioxidant in the vitreous humor, its physiological concentration (1-2 mM) has been shown to be toxic to retinal and lens epithelial cells in in vitro cell culture. We have explored adding vitamin C to hydrogel vitreous substitutes as a potential therapeutic to prevent oxidative damage to intraocular tissues after vitrectomy. However, vitamin C degrades rapidly even when loaded at high concentrations, limiting its long-term effectiveness. Glutathione, another antioxidant found abundantly in the lens at concentrations of 2-10 mM, was proposed to be used in conjunction with vitamin C.

METHODS

Cell viability and reactive oxygen species activity of human retinal and lens epithelial cells treated with various combinations of vitamin C, glutathione, hydrogen peroxide, and a hydrogel vitreous substitute were determined using CellTiter-Glo luminescent cell viability assay and dichlorofluorescein assay, respectively. The vitamin C remaining in hydrogel vitreous substitute or glutathione-vitamin C solutions was determined using a microplate reader at 265 nm wavelength, compared against standard solutions with known concentrations.

RESULTS

Glutathione protected the lens and retinal cells from the negative effect of vitamin C on cell viability and prolonged the antioxidant effect of vitamin C in vitro. While the detected reading of pure vitamin C solution decreased rapidly from 100% to 10% by 3 days, glutathione provided a significant extension to vitamin C stability, with 70% remaining after 14 days when the glutathione was used at physiological concentrations found in the lens (2-10 mM).

CONCLUSIONS

These results indicate glutathione might be an effective addition to vitamin C in intraocular implants, including potential vitreous substitutes, and warrants additional studies on the effectiveness of the vitamin C - glutathione combination in preventing oxidative stress post-vitrectomy.

Nutritional and medical food therapies for diabetic retinopathy

Diabetic retinopathy (DR) is a form of microangiopathy. Reducing oxidative stress in the mitochondria and cell membranes decreases ischemic injury and end-organ damage to the retina. New approaches are needed, which reduce the risk and improve the outcomes of DR while complementing current therapeutic approaches. Homocysteine (Hcy) elevation and oxidative stress are potential therapeutic targets in DR. Common genetic polymorphisms such as those of methylenetetrahydrofolate reductase (MTHFR), increase Hcy and DR risk and severity. Patients with DR have high incidences of deficiencies of crucial vitamins, minerals, and related compounds, which also lead to elevation of Hcy and oxidative stress. Addressing the effects of the MTHFR polymorphism and addressing comorbid deficiencies and insufficiencies reduce the impact and severity of the disease. This approach provides safe and simple strategies that support conventional care and improve outcomes. Suboptimal vitamin co-factor availability also impairs the release of neurotrophic and neuroprotective growth factors. Collectively, this accounts for variability in presentation and response of DR to conventional therapy. Fortunately, there are straightforward recommendations for addressing these issues and supporting traditional treatment plans. We have reviewed the literature for nutritional interventions that support conventional therapies to reduce disease risk and severity. Optimal combinations of vitamins B1, B2, B6, L-methylfolate, methylcobalamin (B12), C, D, natural vitamin E complex, lutein, zeaxanthin, alpha-lipoic acid, and n-acetylcysteine are identified for protecting the retina and choroid. Certain medical foods have been successfully used as therapy for retinopathy. Recommendations based on this review and our clinical experience are developed for clinicians to use to support conventional therapy for DR. DR from both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have similar retinal findings and responses to nutritional therapies.

Current Trends in the Pharmacotherapy of Cataracts

Cataracts, one of the leading causes of preventable blindness worldwide, refers to lens degradation that is characterized by clouding, with consequent blurry vision. As life expectancies improve, the number of people affected with cataracts is predicted to increase worldwide, especially in low-income nations with limited access to surgery. Although cataract surgery is considered safe, it is associated with some complications such as retinal detachment, warranting a search for cheap, pharmacological alternatives to the management of this ocular disease. The lens is richly endowed with a complex system of non-enzymatic and enzymatic antioxidants which scavenge reactive oxygen species to preserve lens proteins. Depletion and/or failure in this primary antioxidant defense system contributes to the damage observed in lenticular molecules and their repair mechanisms, ultimately causing cataracts. Several attempts have been made to counteract experimentally induced cataract using in vitro, ex vivo, and in vivo techniques. The majority of the anti-cataract compounds tested, including plant extracts and naturally-occurring compounds, lies in their antioxidant and/or free radical scavenging and/or anti-inflammatory propensity. In addition to providing an overview of the pathophysiology of cataracts, this review focuses on the role of various categories of natural and synthetic compounds on experimentally-induced cataracts.

Standardization of a new method for assessing the development of cataract in cultured bovine lenses

PURPOSE

To standardize a new method for assessing cataractogenesis in isolated cultured bovine lenses using L-cysteine as the standard anti-cataract agent.

METHODS

Intact bovine lenses were cultured in DMEM with L-cysteine in presence or absence of hydrogen peroxide (H₂O₂). Lens opacity (transmittance) was determined using a plate reader. Lens homogenate glutathione (GSH) and superoxide dismutase (SOD) contents were measured using enzyme immunoassays kits.

RESULTS

DMEM-cultured lenses exhibited a time-dependent loss in transmittance (230-710 nm) up to 120 h, achieving the highest reduction of 38.6 ± 0.09% at 420 nm (p < .001;n = 12). Compared to untreated lenses (time in hours [t] = 0), L-cysteine (10^-6 M and 10^-5 M) significantly (p < .001;n = 6) increased time-dependent transmittance (420 nm) by 31.6 ± 0.17% and 28.0 ± 0.07%(t = 120), respectively. When compared to DMEM-cultured lenses (t = 0), H₂O₂ (10 mM, 50 mM and 100 mM) significantly (p < .001;n = 12) reduced transmittance by 57.8 ± 0.1, 57.4 ± 0.04 and 87.7 ± 0.6%(t = 120), respectively. Moreover, L-cysteine significantly (p < .001;n = 6) attenuated H₂O₂ (50 mM)-induced decrease in transmittance by 12.5 ± 0.05%(10^-6 M), 13.0 ± 0.09%(10^-5 M), 14.5 ± 0.08%(10^-4 M) and 8.6 ± 0.11%(10^-3 M)(t = 120), respectively. When compared to untreated lenses (t = 0), the time-dependent decrease (p < .001;n = 5) in lenticular total GSH content and total SOD activity of 46.1 ± 0.06% and 42.0 ± 1.65% (t = 120) was attenuated (p < .001;n = 5) by L-cysteine (10^-6 M) by 76.6 ± 0.06% and 7.4 ± 1.98%, respectively. Similarly, the H₂O₂(50 mM)-induced decline (p < .001; n = 5) in total GSH content and SOD activity of 82.6 ± 0.08% and 86.6 ± 0.66% (t = 120) was attenuated by L-cysteine (10^-4 M) by 74.7 ± 1.05% and 161.1 ± 4.9%, respectively.

CONCLUSION

Measurement of spectral transmission coupled with assessment of the activity of antioxidant enzymes in bovine cultured lens can provide a useful tool in studies of cataracts in an animal model of this disease.

Ultraviolet radiation oxidative stress affects eye health

In the eye, ultraviolet radiation (UVR) is not known to contribute to visual perception but to mainly damage multiple structures. UVR carries higher energy than visible light and high dose exposure to UVR causes direct cellular damage, which has an important role in the development of cancer. This review provides an overview on the most recent knowledge on the role of UVR in oxidative stress (OS) in relation to noncancer ocular pathologies: various corneal pathologies, cataract, glaucoma and age-related macular degeneration. Possible OS signaling streams and mechanisms in the aging eye are discussed. Excessive exposure to UVR through live may seriously contribute to increase in OS of various eye tissues and thus lead to the advancement of serious ocular pathologies. Children are especially vulnerable to UVR because of their larger pupils and more transparent ocular media: up to 80% of a person's lifetime exposure to UVR is reached before the age of 18. Therefore, efficient everyday protection of the sensitive tissues of the eye by wearing of sunglasses, clear UVR-blocking spectacles or contact lenses should be considered from early age on. Many initiatives are taken worldwide to inform and raise the population's awareness about these possible UVR hazards to the eye.

A novel tool reflecting the role of oxidative stress in the cataracts: thiol/disulfide homeostasis

We investigated serum and aqueous humor thiol/disulfide (T-D) homeostasis in patients with cataracts versus healthy controls. In total, 56 patients with cataracts and 49 healthy controls were enrolled in this case-control study. Serum total thiol (TT), native thiol (NT), and disulfide (DS) concentrations were determined using a novel automated measurement method. Additionally, DS/TT, DS/NT and NT/TT percentage ratios were compared between the groups. In comparison with the control group, serum NT levels and aqueous humor TT and NT levels were significantly lower (p < .05, p < .05 and p < .001, respectively), whereas serum and aqueous humor DS levels were significantly higher in cataract patients (p < .01 and p < .001). DS/TT and DS/NT ratios were significantly higher and the NT/TT ratio was lower in cataract patients in serum (p < .005) and aqueous humor samples (p < .001). In conclusion, serum T-D homeostasis may be useful as biochemical markers, indicating the role of oxidative stress in the development of cataracts. Further studies are needed to confirm the pathophysiological role of T-D homeostasis in cataractogenesis.

Oxidative Stress Plays an Important Role in the Pathogenesis of Drug-Induced Retinopathy

Several pharmaceutical agents have been associated with rare but serious retinopathies, some resulting in blindness. Little is known of the mechanism(s) that produce these injuries. Mechanisms proposed thus far have not been embraced by the medical and scientific communities. However, preclinical and clinical data indicate that oxidative stress may contribute substantially to iatrogenic retinal disease. Retinal oxidative stress may be precipitated by the interaction of putative retinal toxins with the ocular redox system. The retina, replete with cytochromes P450 and myeloperoxidase, may serve to activate xenobiotics to oxidants, resulting in ocular injury. These activated agents may directly form retinal adducts or may diminish ocular reduced glutathione concentrations. Data are reviewed that suggest that indomethacin, tamoxifen, thioridazine, and chloroquine all produce retinopathies via a common mechanism—they produce ocular oxidative stress.

Crosstalk between liver antioxidant and the endocannabinoid systems after chronic administration of the FAAH inhibitor, URB597, to hypertensive rats

Hypertension is accompanied by perturbations to the endocannabinoid and antioxidant systems. Thus, potential pharmacological treatments for hypertension should be examined as modulators of these two metabolic systems. The aim of this study was to evaluate the effects of chronic administration of the fatty acid amide hydrolase (FAAH) inhibitor [3-(3-carbamoylphenyl)phenyl]N-cyclohexylcarbamate (URB597) on the endocannabinoid system and on the redox balance in the livers of DOCA-salt hypertensive rats. Hypertension caused an increase in the levels of endocannabinoids [anandamide (AEA), 2-arachidonoyl-glycerol (2-AG) and N-arachidonoyl-dopamine (NADA)] and CB1 receptor and the activities of FAAH and monoacylglycerol lipase (MAGL). These effects were accompanied by an increase in the level of reactive oxygen species (ROS), a decrease in antioxidant activity/level, enhanced expression of transcription factor Nrf2 and changes to Nrf2 activators and inhibitors. Moreover, significant increases in lipid, DNA and protein oxidative modifications, which led to enhanced levels of proapoptotic caspases, were also observed. URB597 administration to the hypertensive rats resulted in additional increases in the levels of AEA, NADA and the CB1 receptor, as well as decreases in vitamin E and C levels, glutathione peroxidase and glutathione reductase activities and Nrf2 expression. Thus, after URB597 administration, oxidative modifications of cellular components were increased, while the inflammatory response was reduced. This study revealed that chronic treatment of hypertensive rats with URB597 disrupts the endocannabinoid system, which causes an imbalance in redox status. This imbalance increases the levels of electrophilic lipid peroxidation products, which later participate in metabolic disturbances in liver homeostasis.

Thioredoxin reductase activity may be more important than GSH level in protecting human lens epithelial cells against UVA light

This study compares the abilities of the glutathione (GSH) and thioredoxin (Trx) antioxidant systems in defending cultured human lens epithelial cells (LECs) against UVA light. Levels of GSH were depleted with either L-buthionine-(S,R)-sulfoximine (BSO) or 1-chloro-2,4-dinitrobenzene (CDNB). CDNB treatment also inhibited the activity of thioredoxin reductase (TrxR). Two levels of O2 , 3% and 20%, were employed during a 1 h exposure of the cells to 25 J cm(-2) of UVA radiation (338-400 nm wavelength, peak at 365 nm). Inhibition of TrxR activity by CDNB, combined with exposure to UVA light, produced a substantial loss of LECs and cell damage, with the effects being considerably more severe at 20% O2 compared to 3%. In contrast, depletion of GSH by BSO, combined with exposure to UVA light, produced only a slight cell loss, with no apparent morphological effects. Catalase was highly sensitive to UVA-induced inactivation, but was not essential for protection. Although UVA light presented a challenge for the lens epithelium, it was well tolerated under normal conditions. The results demonstrate an important role for TrxR activity in defending the lens epithelium against UVA light, possibly related to the ability of the Trx system to assist DNA synthesis following UVA-induced cell damage.

Lycium barbarum polysaccharides protect human lens epithelial cells against oxidative stress-induced apoptosis and senescence

Objectives

We aimed to investigate the protective effect of Lycium barbarum polysaccharides (LBPs) against oxidative stress–induced apoptosis and senescence in human lens epithelial cells.

Methods

To study apoptosis, SRA01/04 cells, a human lens epithelial cell lines, were exposed to 200 µM hydrogen peroxide (H₂O₂) for 24 h with or without pretreatment with LBPs. Cell viability was measured using a Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis, intracellular reactive oxygen species (ROS), and the loss of mitochondria membrane potential (Δψm) were detected by flow cytometric analyses. Expression levels of Bcl-2 and Bax proteins were measured by western blot analysis. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) were quantized using commercial enzymatic kits according to the manufacturer's instructions. To study senescence, SRA01/04 cells were pre-incubated with LBPs and all cells were then exposed to 100 µM H₂O₂ for 96 h. Cellular senescence was assessed by morphologic examination and senescence-associated β-galactosidase (SA-β-gal) staining.

Results

LBPs significantly reduced H₂O₂-induced cell apoptosis, the generation of ROS, the loss of Δψm, and the levels of MDA. LBPs also inhibited H₂O₂-induced downregulated Bcl-2 and upregulated Bax proteins and increased the levels of SOD and GSH enzyme activity. Moreover, LBPs significantly attenuated H₂O₂-induced cellular senescence.

Conclusions

These findings suggested that LBPs protect human lens epithelial cells from H₂O₂-induced apoptosis by modulating the generation of ROS, loss of Δψm, Bcl-2 family, and antioxidant enzyme activity and attenuating cellular senescence.

Polymorphisms in sodium-dependent vitamin C transporter genes and plasma, aqueous humor and lens nucleus ascorbate concentrations in an ascorbate depleted setting

We have previously reported low concentrations of plasma ascorbate and low dietary vitamin C intake in the older Indian population and a strong inverse association of these with cataract. Little is known about ascorbate levels in aqueous humor and lens in populations habitually depleted of ascorbate and no studies in any setting have investigated whether genetic polymorphisms influence ascorbate levels in ocular tissues. Our objectives were to investigate relationships between ascorbate concentrations in plasma, aqueous humor and lens and whether these relationships are influenced by Single Nucleotide Polymorphisms (SNPs) in sodium-dependent vitamin C transporter genes (SLC23A1 and SLC23A2). We enrolled sixty patients (equal numbers of men and women, mean age 63 years) undergoing small incision cataract surgery in southern India. We measured ascorbate concentrations in plasma, aqueous humor and lens nucleus using high performance liquid chromatography. SLC23A1 SNPs (rs4257763, rs6596473) and SLC23A2 SNPs (rs1279683 and rs12479919) were genotyped using a TaqMan assay. Patients were interviewed for lifestyle factors which might influence ascorbate. Plasma vitamin C was normalized by a log10 transformation. Statistical analysis used linear regression with the slope of the within-subject associations estimated using beta (β) coefficients. The ascorbate concentrations (μmol/L) were: plasma ascorbate, median and inter-quartile range (IQR), 15.2 (7.8, 34.5), mean (SD) of aqueous humor ascorbate, 1074 (545) and lens nucleus ascorbate, 0.42 (0.16) (μmol/g lens nucleus wet weight). Minimum allele frequencies were: rs1279683 (0.28), rs12479919 (0.30), rs659647 (0.48). Decreasing concentrations of ocular ascorbate from the common to the rare genotype were observed for rs6596473 and rs12479919. The per allele difference in aqueous humor ascorbate for rs6596473 was -217 μmol/L, p < 0.04 and a per allele difference in lens nucleus ascorbate of -0.085 μmol/g, p < 0.02 for rs12479919. The β coefficients for the regression of log10 plasma ascorbate on aqueous humor ascorbate were higher for the GG genotype of rs6596473: GG, β = 1460 compared to carriage of the C allele, CG, β = 1059, CC, β = 1132, p interaction = 0.1. In conclusion we found that compared to studies in well-nourished populations, ascorbate concentrations in the plasma, aqueous humor and lens nucleus were low. We present novel findings that polymorphisms in SLC23A1/2 genes influenced ascorbate concentration in aqueous humor and lens nucleus.

Lipid peroxidation: pathophysiological and pharmacological implications in the eye

Oxygen-derived free radicals such as hydroxyl and hydroperoxyl species have been shown to oxidize phospholipids and other membrane lipid components leading to lipid peroxidation. In the eye, lipid peroxidation has been reported to play an important role in degenerative ocular diseases (age-related macular degeneration, cataract, glaucoma, diabetic retinopathy). Indeed, ocular tissues are prone to damage from reactive oxygen species due to stress from constant exposure of the eye to sunlight, atmospheric oxygen and environmental chemicals. Furthermore, free radical catalyzed peroxidation of long chain polyunsaturated acids (LCPUFAs) such as arachidonic acid and docosahexaenoic acid leads to generation of LCPUFA metabolites including isoprostanes and neuroprostanes that may further exert pharmacological/toxicological actions in ocular tissues. Evidence from literature supports the presence of endogenous defense mechanisms against reactive oxygen species in the eye, thereby presenting new avenues for the prevention and treatment of ocular degeneration. Hydrogen peroxide (H2O2) and synthetic peroxides can exert pharmacological and toxicological effects on tissues of the anterior uvea of several mammalian species. There is evidence suggesting that the retina, especially retinal ganglion cells can exhibit unique characteristics of antioxidant defense mechanisms. In the posterior segment of the eye, H2O2 and synthetic peroxides produce an inhibitory action on glutamate release (using [(3)H]-D-aspartate as a marker), in vitro and on the endogenous glutamate and glycine concentrations in vivo. In addition to peroxides, isoprostanes can elicit both excitatory and inhibitory effects on norepinephrine (NE) release from sympathetic nerves in isolated mammalian iris ciliary bodies. Whereas isoprostanes attenuate dopamine release from mammalian neural retina, in vitro, these novel arachidonic acid metabolites exhibit a biphasic regulatory effect on glutamate release from retina and can regulate amino acid neurotransmitter metabolism without inducing cell death in the retina. Furthermore, there appears to be an inhibitory role for neuroprostanes in the release of excitatory amino acid neurotransmitters in mammalian retina. The ability of peroxides and metabolites of LCPUFA to alter the integrity of neurotransmitter pools provides new potential target sites and pathways for the treatment of degenerative ocular diseases.

Bioactive-rich Sideritis scardica tea (mountain tea) is as potent as Camellia sinensis tea at inducing cellular antioxidant defences and preventing oxidative stress

BACKGROUND

In several countries, tea (hot-water infusions of dried Camellia sinensis (CS) leaves) is a major source of antioxidant flavonoids, and its consumption has been associated with several favourable outcomes. Other plants used for the preparation of herbal teas are sources of phenolic antioxidant compounds; among them Sideritis scardica (SS) is used for the preparation of a popular drink throughout Eastern and Central Europe. We have compared the effects of an SS extract to a CS extract in HepG2 cells to set the scientific basis for the exploitation of other herbal teas in counteraction of oxidative stress.

RESULTS

Although SS extract had a lower phenolic concentration and total antioxidant capacity than CS extract, their cellular antioxidant effects were similar. The different phenolic pattern of the extracts suggests that the protective activity is not limited to catechins.

CONCLUSION

Although further research is needed, our data represent a first contribution for the evaluation of the potential effect of SS in increasing antioxidant defences. © 2013 Society of Chemical Industry.

Fruit and vegetable intake and vitamins C and E are associated with a reduced prevalence of cataract in a Spanish Mediterranean population

BACKGROUND

Cataract is among the major causes of vision impairment and blindness worldwide. Epidemiological studies support the role of antioxidants in the etiology of cataract, but the evidence for one specific antioxidant over another is inconsistent. Few studies have examined the association of cataract with fruit and vegetable intake with inconclusive results. In the present study, the relationship between cataract and fruit and vegetable intake and dietary and blood levels of carotenoids, vitamins C and E were examined in a Spanish Mediterranean population.

METHODS

The present work is an analysis of data from 599 elderly ( ≥ 65 years) participants from the Spanish segment of the EUREYE study. This is a European multi-center cross-sectional population-based study. Cataract was diagnosed using a slit-lamp examination and defined as any lens opacity in either eye or evidence of its removal (cataract extraction). Energy-adjusted intake of fruit and vegetables and antioxidant vitamins was estimated using a semi-quantitative food frequency questionnaire. Plasma concentrations of vitamin C were analyzed by a colorimetric method and carotenoids and α-tocopherol by a HPLC method. The associations between cataract and quartiles of fruit and vegetable intake and plasma antioxidants were investigated using logistic regression models.

RESULTS

Of the 599 elderly recruited, 433 (73%) had cataract or cataract extraction, 54% were women and 46% were men. After adjustments, increasing quartiles of combined fruit and vegetable intake were associated with decreasing reduction of odds of cataract or cataract extraction, (P for trend = 0.008). Increasing quartiles of dietary intakes from 107 mg/d of vitamin C showed a significant decreasing association with prevalence of cataract or cataract extraction (P for trend = 0.047). For vitamin E, a protective association was found from intakes from 8 mg/d, but no linear trend was observed across quartiles of intake (P for trend = 0.944).

CONCLUSIONS

High daily intakes of fruit and vegetables and vitamins C and E were associated with a significantly decreased of the prevalence of cataract or cataract surgery. This study reinforces the WHO recommendations on the benefits of diets rich in fruit and vegetables.

Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies

BACKGROUND

Observational studies have been inconsistent regarding the association between blood antioxidants or vitamins and risk of age-related cataract.

OBJECTIVE

We performed a meta-analysis to determine whether an association exists between blood levels of antioxidants or vitamins and age-related cataract in observational studies.

DESIGN

We searched PubMed, EMBASE, and the Web of Science for relevant studies from inception to October 2012. Study-specific risk estimates were combined by using a random-effects model.

RESULTS

A total of 13 studies with 18,999 participants were involved in this meta-analysis. A pooled estimate showed vitamin E (OR: 0.75; 95% CI: 0.58, 0.96), α-carotene (OR: 0.72; 95% CI: 0.59, 0.88), lutein (OR: 0.75; 95% CI: 0.65, 0.87), and zeaxanthin (OR: 0.70; 95% CI: 0.60, 0.82) were inversely associated with age-related cataract. Vitamins A (OR: 0.69; 95% CI: 0.58, 0.83) and C (OR: 0.67; 95% CI: 0.57, 0.78) were inversely associated with age-related cataract in Asian populations but not in Western populations. β-Carotene (OR: 0.90; 95% CI: 0.78, 1.05), lycopene (OR: 0.86; 95% CI: 0.65, 1.15), and β-cryptoxanthin (OR: 0.83; 95% CI: 0.68, 1.02) had no significant association with risk of cataract.

CONCLUSIONS

This meta-analysis provides additional evidence supporting the view that blood levels of certain antioxidants are inversely associated with risk of age-related cataract. However, the role of antioxidant or vitamin supplement intake in preventing cataract should be further investigated in interventional studies.

High-dose supplements of vitamins C and E, low-dose multivitamins, and the risk of age-related cataract: a population-based prospective cohort study of men

We examined the associations of high-dose supplements of vitamins C and E and low-dose multivitamins with the risk of age-related cataract among 31,120 Swedish men, aged 45-79 years, in a population-based prospective cohort. Dietary supplement use was assessed from a questionnaire at baseline in 1998. During follow-up (January 1998-December 2006), 2,963 incident age-related cataract cases were identified. The multivariable-adjusted hazard ratio for men using vitamin C supplements only was 1.21 (95% confidence interval (CI): 1.04, 1.41) in a comparison with that of non-supplement users. The hazard ratio for long-term vitamin C users (≥10 years before baseline) was 1.36 (95% CI: 1.02, 1.81). The risk of cataract with vitamin C use was stronger among older men (>65 years) (hazard ratio = 1.92, 95% CI: 1.41, 2.60) and corticosteroid users (hazard ratio = 2.11, 95% CI: 1.48, 3.02). The hazard ratio for vitamin E use only was 1.59 (95% CI: 1.12, 2.26). Use of multivitamins only or multiple supplements in addition to vitamin C or E was not associated with cataract risk. These results suggest that the use of high-dose (but not low-dose) single vitamin C or E supplements may increase the risk of age-related cataract. The risk may be even higher among older men, corticosteroid users, and long-term users.

Effects of radical scavenger protein from broad beans on glutathione status in human lung fibroblasts

OBJECTIVE

Human diploid cells are more susceptible to oxidative stress at late passage than at early passage, presumably because of the decrease in cellular-reduced glutathione (GSH) concentration. Water-soluble protein (WSP) from broad beans scavenges free radicals. The effects of WSP on the glutathione system were examined in PDL 20 (early passage) and PDL 50 (late passage) human lung fibroblasts (TIG-1).

METHODS

To determine cytosolic glutathione peroxidase (GSH-Px) activities, glutathione reductase (GR) activities, oxidized glutathione (GSSG) concentrations, and GSSG/reduced glutathione (GSH) ratios, WSP and hydrocortisone (HC) treatments of TIG-1 cells (PDL 20→50 and PDL 50→75) were performed for 40 days. We also investigated the GSSG concentrations and GR activities in PDL 20 cells that were continuously treated with WSP until PDL 39 and 55.

RESULTS

GSSG concentrations decreased in WSP- and HC-treated PDL 50→75 cells. The GSSG/GSH ratios in PDL 50→75 cells became low after the treatments. Increases in GR activities were observed in treated PDL 50→75 cells. The decline in the GSSG concentration of PDL 50→75 cells correlated with the increase in GR activity. The GSSG levels in control cells were higher following cellular age, whereas the levels in treated cells were lower than those in the control. The studies on cellular age-related changes indicated that greater increases in GR activity were found in treated cells than in the control.

CONCLUSION

These results indicated that WSP influences the GSSG concentration that is associated with cellular aging, but the mechanism of GSSG reduction by WSP remains unknown. The enhancement of glutathione status following WSP treatment may be related to the delay in the cellular aging.

High lenticular tolerance to ultraviolet radiation-B by pigmented guinea-pig; application of a safety limit strategy for UVR-induced cataract

PURPOSE

The purpose of this study was to determine a threshold measure, maximum tolerable dose (MTD), for avoidance of UVR-B-induced cataract in the pigmented guinea-pig.

METHODS

Thirty pupil-dilated anesthetized young female guinea-pigs, divided into five equal groups, received between 0 and 84.9 kJ/m(2) unilateral UVR-B. Lens extraction and in vitro lens photography occurred 24 hr after exposure. Measurement of intensity of lens light scattering served as quantifying tool for the degree of cataract. Data analysis included regression, using a second order polynomial model. The applied MTD concept was based on the UVR-B dose-response curve obtained for the pigmented guinea-pig. A smaller number of pigmented guinea-pigs, pigmented rats and albino rats underwent morphometric analysis of the anterior segment geometry.

RESULTS

All eyes exposed to UVR-B developed cataract in the anterior subcapsular region. MTD for avoidance of UVR-B-induced cataract was 69.0 kJ/m(2) in the pigmented guinea-pig. Iris was considerably thicker in the guinea-pig than in the rats. Lens blockage by the dilated iris was lowest in the guinea-pig.

CONCLUSIONS

Maximum tolerable dose for avoidance of UVR-B-induced cataract in the pigmented guinea-pig was 69.0 kJ/m(2), over 10-fold higher than the threshold 5 kJ/m(2) obtained by Pitts et al. in the pigmented rabbit. Maximum tolerable dose is an appropriate method for estimation of toxicity for UVR-B-induced cataract in the guinea-pig. The pigmented guinea-pig is significantly less sensitive to UVR-B exposure than the pigmented rabbit and pigmented rat.

γ-Tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury

Background

Down syndrome (DS) neurons are more susceptible to oxidative stress and previous studies have shown that vitamin E was able to reduce oxidative stress and improve DS neurons' viability. Therefore, this study was done to investigate the protective role of γ-tocotrienol (γT3) in DS neurons from hydrogen peroxide (H₂O₂) -induced oxidative stress. The pro-apoptosis tendency of γT3 was compared to α-tocopherol (αT) in non-stress condition as well.

Methods

Primary culture of DS and euploid neurons were divided into six groups of treatment: control, H₂O₂, γT3 pre-treatment with H₂O₂, γT3 only, αT pre-treatment with H₂O₂ and αT only. The treatments were assessed by MTS assay and apoptosis assay by single-stranded DNA (ssDNA) apoptosis ELISA assay, Hoechst and Neu-N immunofluorescence staining. The cellular uptake of γT3 and αT was determined by HPLC while protein expressions were determined by Western blot. Comparison between groups was made by the Student's t test, one-way ANOVA and Bonferroni adjustment as well as two-way ANOVA for multiple comparisons.

Results

One day incubation of γT3 was able to reduced apoptosis of DS neurons by 10%, however γT3 was cytotoxic at longer incubation period (14 days) and at concentrations ≥ 100 μM. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H₂O₂-treated DS and euploid neurons by 10% in which the effects were minimal to maintain most of the DS cells' morphology. γT3 act as a free radical scavenger by reducing ROS generated by H₂O₂. In untreated controls, DS neurons showed lower Bcl-2/Bax ratio and p53 expression compared to normal neurons, while cPKC and PKC-δ expressions were higher in DS neurons. On the other hand, pre-treatment of γT3 in H₂O₂-treated DS neurons have reduced Bcl-2/Bax ratio, which was not shown in euploid neurons. This suggests that pre-treatment of γT3 did not promote DS cell survival. Meanwhile γT3 and αT treatments without H₂O₂ as well as pre-treatment of γT3 and αT induced changes in cPKC and PKC-δ expression in DS neurons suggesting interaction of γT3 and αT with PKC activity.

Conclusion

Our study suggests that γT3 pre-treatment are not sufficient to protect DS neurons from H₂O₂-induced oxidative assault, instead induced the apoptosis process.