Intracellular Antioxidant Glutathione Research Articles

Accelerating Ce3+/Ce4+ Conversion in CeO2 via Mn doping to Endow Scaffolds with Chemodynamic Therapy Properties

CeO2 nanozymes have garnered significant attention in chemodynamic therapy due to their peroxidase-like activity and ability to deplete glutathione. However, their catalytic efficiency is constrained by the low conversion rate of Ce3+/Ce4+. To overcome this limitation, the electron transfer was accelerated by introducing the transition metal Mn atom as a valence electron donor through lattice charge transfer. In detail, we introduced Ce1-xMnxO2 into the poly-L-lactic acid (PLLA) scaffold fabricated by selective laser sintering. The conversion from Ce3+ to Ce4+ promoted the decomposition of H2O2 within the tumor microenvironment to generate hydroxyl radicals with high oxidative activity, consequently inducing oxidative stress. The conversion from Ce4+ to Ce3+ depleted intracellular antioxidant glutathione, disrupting redox balance in tumor cells. This continuous redox cycle ultimately triggered apoptosis in tumor cells. Using a first-principles Hubbard-corrected approximate density-functional method, the analysis of the electron band structure revealed the presence of donor energy levels within the bandgap of Ce1-xMnxO2, enabling electron transfer channels around 0.645 eV. Electrochemical experiments confirmed that Ce0.8Mn0.2O2 significantly reduced the activation overpotential from 0.907 V to 0.646 V, enhancing its redox capacity. As a result, the scaffold exhibited a threefold increase in tumor-killing rate. These findings highlight the immense potential of CeO2 nanozymes in enhancing chemodynamic therapy for effective tumor treatment.

Effects of Arbutin on Potassium Bromate-Induced Erythrocyte Toxicity in Rats: Biochemical Evaluation of Some Metabolic Enzyme Activities In Vivo and In Vitro.

In the present study, the inhibitory effect of potassium bromate on the pentose phosphate pathway and intracellular antioxidant systems enzymes (glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR), glutathione S-transferase (GST), and thioredoxin reductase (TrxR)) and the role of arbutin in ameliorating this inhibition were investigated. In the in vivo phase of the study, Wistar Albino rats (28 male adults) were randomly divided into four groups. Control (n = 7): isotonic serum (0.5 mL, i.p), potassium bromate group (n = 7): potassium bromate (100 mg/kg), arbutin group (n = 7): arbutin (i.p.) (50 mg/kg/day), potassium bromate + arbutin, and Group (n = 7): potassium bromate (100 mg/kg) + arbutin (50 mg/kg/day) (i.p). The results of in vivo study showed that the activities of G6PD, 6PGD, GR, and TrxR enzymes were strongly inhibited in potassium bromate groups (p < 0.05). It was determined that GST enzyme activity decreased in the potassium bromate group, but this decrease was not statistically significant compared to the control group (p ⩾ 0.05). A statistically significant increase was found in G6PD, 6PGD, GST, and TrxR enzyme activities in the arbutin group compared to the control group (p < 0.05). The increase in GR enzyme activity was not statistically significant (p ⩾ 0.05). The potassium bromate + arbutin group's enzyme activity increased in comparison to the potassium bromate group and was discovered to be closer to the control group. It was found that potassium bromate inhibited the 6PGD enzyme obtained from rat erythrocyte tissues with IC50 = 346 μM value and Ki = 434.4 μM ± 6.1 value, and the inhibition was noncompetitive.

Defect-passivated metal halide perovskite quantum dots stabilized into biodegradable porous polydopamine nanoparticles for photothermal/chemodynamic/gas therapy of cancer

Herein, we reported a one-pot synthesis of CsPbBr3 quantum dots (QDs) passivated with diammonium sulfide (NH4)2S additive using the probe-sonication technique. (NH4)2S-treated CsPbBr3 (NS-CsPbBr3) QDs exhibited superior optical properties compared to untreated QDs. The aqueous stability of NS-CsPbBr3 QDs was improved by physical loading into porous manganese (Mn)-enriched polydopamine nanoparticles (mPDA NPs) via physical adsorption strategy, followed by functionalization with folic acid (FA), resulting in multifunctional nanospheres (denoted as NCPB@mPDA/FA NSs). The Mn2+ and S2- ions in the NCPB@mPDA/FA NSs generated cytotoxic •OH radicals for chemodynamic treatment (CDT) and H2S gas for gas therapy (GT) under acidic conditions, respectively. Furthermore, the intracellular antioxidant glutathione was significantly blocked using NCPB@mPDA/FA for enhanced CDT efficiency. Upon 808 nm laser irradiation, the green-emitting NCPB@mPDA/FA NSs demonstrated not only outstanding photothermal therapy (Ƞ=41.5%) due to considerable absorption in the near-infrared range but also stimulated the release of Mn2+ and S2- ions for photothermal-triggered CDT and GT of cancer. The cancer cells effectively internalized NCPB@mPDA/FA through CD44 folate receptors, leading to a bright cellular image. Additionally, when combined with laser and H2O2, NCPB@mPDA/FA exhibited significant effectiveness against HeLa and 4T1 cells. Upon intravenous administration, NCPB@mPDA/FA exhibited notable tumor accumulation, resulting in enhanced tumor suppression in vivo, attributed to the improved hyperthermia-induced CDT and GT. The in vivo tumor inhibition potential of perovskite QD-based materials was demonstrated for the first time, indicating their therapeutic capabilities.

Bismuth Oxide (Bi2O3) Nanoparticles Cause Selective Toxicity in a Human Endothelial (HUVE) Cell Line Compared to Epithelial Cells.

A review of recent literature suggests that bismuth oxide (Bi2O3, referred to as B in this article) nanoparticles (NPs) elicit an appreciable response only after a concentration above 40-50 µg/mL in different cells all having an epithelial origin, to the best of our knowledge. Here, we report the toxicological profile of Bi2O3 NPs (or BNPs) (71 ± 20 nm) in a human endothelial cell (HUVE cell line) in which BNPs exerted much steeper cytotoxicity. In contrast to a high concentration of BNPs (40-50 µg/mL) required to stimulate an appreciable toxicity in epithelial cells, BNPs induced 50% cytotoxicity in HUVE cells at a very low concentration (6.7 µg/mL) when treated for 24 h. BNPs induced reactive oxygen species (ROS), lipid peroxidation (LPO), and depletion of the intracellular antioxidant glutathione (GSH). BNPs also induced nitric oxide (NO,) which can result in the formation of more harmful species in a fast reaction that occurs with superoxide (O2•-). Exogenously applied antioxidants revealed that NAC (intracellular GSH precursor) was more effective than Tiron (a preferential scavenger of mitochondrial O2•-) in preventing the toxicity, indicating ROS production is extra-mitochondrial. Mitochondrial membrane potential (MMP) loss mediated by BNPs was significantly less than that of exogenously applied oxidant H2O2, and MMP loss was not as intensely reduced by either of the antioxidants (NAC and Tiron), again suggesting BNP-mediated toxicity in HUVE cells is extra-mitochondrial. When we compared the inhibitory capacities of the two antioxidants on different parameters of this study, ROS, LPO, and GSH were among the strongly inhibited biomarkers, whereas MMP and NO were the least inhibited group. This study warrants further research regarding BNPs, which may have promising potential in cancer therapy, especially via angiogenesis modulation.

Epstein-Barr virus infection controls the concentration of the intracellular antioxidant glutathione by upregulation of the glutamate transporter EAAT3 in tumor cells.

Epstein-Barr virus or human herpesvirus 4 (EBV/HHV-4) is an omnipresent oncovirus etiologically associated with various B-cell lymphomas and epithelial cancers. The malignant transformation associated with the persistent expression of viral proteins often deregulates the host cellular machinery and EBV infection is coupled to elevated levels of reactive oxygen species. Here, we investigated the role that the glutamate transporter EAAT3 plays in regulating the antioxidant system as a protective mechanism of EBV-infected cells against the virus-induced oxidative stress. Our study demonstrated that the expression of EAAT3 was upregulated and localized to the plasma membrane in EBV latently infected and de novo EBV-infected cells. EAAT3 was regulated by the transcription factor NFAT5 in the infected cells. Membrane localized EAAT3 was found to be involved in the transportation of glutamate from the extracellular space into the cell, as EAAT3 and NFAT5 inhibitors markedly reduced the levels of intracellular glutamate levels in EBV latently infected cells. Additionally, our data demonstrated a notable decrease in the intracellular glutathione levels following treatment with an EAAT3 inhibitor. Collectively, our results suggest that upregulation of the glutamate transporter EAAT3 is an adaptation of EBV-infected cells to maintain cellular redox homeostasis against the virus-induced oxidative stress, and that this cellular balance could be therapeutically destroyed by targeting EAAT3 to impede EBV-associated cancers.

The neuroprotective effect of walnut-derived peptides against glutamate-induced damage in PC12 cells: mechanism and bioavailability

In our previous study, defatted walnut meal hydrolysate (DWMH) could attenuate D-galactose-induced acute memory deficits in vivo, and 6 potent active peptides including WSREEQ, WSREEQE, WSREEQEREE, ADIYTE, ADIYTEEAG and ADIYTEEAGR were identified. The aim of this study was to investigate the possible mechanism underlying their neuroprotective effects on glutamate-induced apoptosis in PC12 cells and their digestive stability. Results showed that all these peptides could attenuate the reduction of cell viability caused by glutamate in PC12 cells, especially WSREEQEREE and ADIYTEEAGR. The addition of Arg residue in WSREEQEREE and ADIYTEEAGR might be the potential reason for their stronger protective effects. Additionally, these two peptides possibly protected PC12 cells against glutamate-induced apoptosis via activating intracellular antioxidant defence (superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px)) through Kelch-like ECH-associated protein 1 (Keap1) inhibition, inhibiting ROS production, Ca2+ influx and mitochondrial membrane potential (MMP) collapse as well as regulating the expression of apoptosis-related proteins (Bax and Bcl-2). This might be due to the presence of Trp, Tyr and Arg in these two peptides. However, encapsulation of WSREEQEREE and ADIYTEEAGR should be considered based on their digestive sensibility during in vitro gastrointestinal digestion.

Nrf2 Regulation by Curcumin: Molecular Aspects for Therapeutic Prospects.

Nuclear factor erythroid 2 p45-related factor (2Nrf2) is an essential leucine zipper protein (bZIP) that is primarily located in the cytoplasm under physiological conditions. Nrf2 principally modulates endogenous defense in response to oxidative stress in the brain.In this regard, Nrf2 translocates into the nucleus and heterodimerizes with the tiny Maf or Jun proteins. It then attaches to certain DNA locations in the nucleus, such as electrophile response elements (EpRE) or antioxidant response elements (ARE), to start the transcription of cytoprotective genes. Many neoplasms have been shown to have over activated Nrf2, strongly suggesting that it is responsible for tumors with a poor prognosis. Exactly like curcumin, Zinc–curcumin Zn (II)–curc compound has been shown to induce Nrf2 activation. In the cancer cell lines analyzed, Zinc–curcumin Zn (II)–curc compound can also display anticancer effects via diverse molecular mechanisms, including markedly increasing heme oxygenase-1 (HO-1) p62/SQSTM1 and the Nrf2 protein levels along with its targets. It also strikingly decreases the levels of Nrf2 inhibitor, Kelch-like ECH-associated protein 1 (Keap1) protein.As a result, the crosstalk between p62/SQSTM1 and Nrf2 could be used to improve cancer patient response to treatments. The interconnected anti-inflammatory and antioxidative properties of curcumin resulted from its modulatory effects on Nrf2 signaling pathway have been shown to improve insulin resistance. Curcumin exerts its anti-inflammatory impact through suppressing metabolic reactions and proteins such as Keap1 that provoke inflammation and oxidation. A rational amount of curcumin-activated antioxidant Nrf2 HO-1 and Nrf2-Keap1 pathways and upregulated the modifier subunit of glutamate-cysteine ligase involved in the production of the intracellular antioxidant glutathione. Enhanced expression of glutamate-cysteine ligase, a modifier subunit (GLCM), inhibited transcription of glutamate-cysteine ligase, a catalytic subunit (GCLC). A variety of in vivo, in vitro and clinical studies has been done so far to confirm the protective role of curcumin via Nrf2 regulation. This manuscript is designed to provide a comprehensive review on the molecular aspects of curcumin and its derivatives/analogs via regulation of Nrf2 regulation.

Lycopene prevents oxygen-glucose deprivation-induced autophagic death in SH-SY5Y cells via inhibition of the oxidative stress-activated AMPK/mTOR pathway.

Lycopene has been reported to exert a protective effect on the brain against transient ischemia‑induced damage; however, whether it could regulate autophagic neuronal death remains elusive. The present study aimed to investigate the role of autophagy in the protective effects of lycopene against neuronal damage and its underlying mechanism. Oxygen‑glucose deprivation (OGD) was used to simulate neuronal ischemic injury in human SH‑SY5Y cells. Lactate dehydrogenase (LDH) release assay revealed that OGD induced SH‑SY5Y cell death. Western blotting demonstrated that OGD upregulated the expression levels of the autophagy marker proteins autophagy protein5(ATG5) and LC3II, but downregulated the autophagy substrate p62 in a time‑dependent manner. By contrast, OGD‑induced cell death was significantly inhibited by the autophagy inhibitors 3‑methyladenine or bafilomycin A1 or by knockdown of ATG5, indicating that OGD may induce autophagic death in SH‑SY5Y cells. Notably, lycopene was shown not only to prevent OGD‑induced SH‑SY5Y cell death, but was also able to effectively inhibit OGD‑induced upregulation of ATG5 and LC3II, and downregulation of p62 in a dose‑dependent manner. Mechanistically, it was suggested that lycopene inhibited OGD‑induced activation of the AMPK/mTOR pathway via attenuation of oxidative stress by maintaining the intracellular antioxidant glutathione (GSH). Furthermore, the inhibitory role of lycopene in GSH depletion was found to be associated with the prevention of OGD‑induced depletion of intracellular cysteine and downregulation of xCT. Collectively, the present study demonstrated that lycopene protected SH‑SY5Y cells against OGD‑induced autophagic death by inhibiting oxidative stress‑dependent activation of the AMPK/mTOR pathway.

Synergistic effect of docosahexaenoic acid or conjugated linoleic acid with caffeic acid on ameliorating oxidative stress of HepG2 cells.

Exploring the synergistic effect of docosahexaenoic acid (DHA) or conjugated linoleic acid (CLA) with caffeic acid (CA) on ameliorating oxidative stress, thereby introducing CA to DHA or CLA will contribute significantly to enhance the bioactivity. We observed that DHA or CLA with CA promoted the recovery of intact individual morphology and the decline of cavities inside the nucleus and apoptosis under the observation of confocal laser scanning microscopy and fluorescent inverted microscope. The activity of intracellular antioxidant enzymes catalase (CAT) and glutathione peroxidase (GSH-Px), lactate dehydrogenase (LDH) leakage, pyruvate and malondialdehyde and reactive oxygen species (ROS), cellular morphology, and cell cycle were analyzed. Our results showed that DHA or CLA with CA enhanced the activity of CAT and GSH-Px, decreased LDH leakage and the number of apoptotic, significantly inhibited (ROS-induced cellular injury. Cell arrest in G1 and G2 phase during cell mitosis was reduced by the measurement of flow cytometry. DHA or CLA combined with CA could markedly strengthen the free radical scavenging and endogenous antioxidant defense capacity on HepG2 cells. This study provides a new direction in the application of synergies to antioxidant compounds. PRACTICAL APPLICATION: Caffeic acid (CA) can synergize with docosahexaenoic acid (DHA) or conjugated linoleic acid (CLA) to enhance antioxidant capacity. This study highlighted an effect of ameliorating oxidative stress injury DHA or CLA with CA on HepG2 cells. The data indicated that DHA or CLA with CA might be used to relieve oxidative stress damage.

Inhibition of the MYC-Regulated Glutaminase Metabolic Axis Is an Effective Synthetic Lethal Approach for Treating Chemoresistant Ovarian Cancers.

Amplification and overexpression of the MYC oncogene in tumor cells, including ovarian cancer cells, correlates with poor responses to chemotherapy. As MYC is not directly targetable, we have analyzed molecular pathways downstream of MYC to identify potential therapeutic targets. Here we report that ovarian cancer cells overexpressing glutaminase (GLS), a target of MYC and a key enzyme in glutaminolysis, are intrinsically resistant to platinum-based chemotherapy and are enriched with intracellular antioxidant glutathione. Deprivation of glutamine by glutamine-withdrawal, GLS knockdown, or exposure to the GLS inhibitor CB-839 resulted in robust induction of reactive oxygen species in high GLS-expressing but not in low GLS-expressing ovarian cancer cells. Treatment with CB-839 rendered GLShigh cells vulnerable to the poly(ADP-ribose) polymerase (PARP) inhibitor, olaparib, and prolonged survival in tumor-bearing mice. These findings suggest consideration of applying a combined therapy of GLS inhibitor and PARP inhibitor to treat chemoresistant ovarian cancers, especially those with high GLS expression. SIGNIFICANCE: Targeting glutaminase disturbs redox homeostasis and nucleotide synthesis and causes replication stress in cancer cells, representing an exploitable vulnerability for the development of effective therapeutics. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/20/4514/F1.large.jpg.

Surface-Charge-Switchable Nanoclusters for Magnetic Resonance Imaging-Guided and Glutathione Depletion-Enhanced Photodynamic Therapy.

Photodynamic therapy (PDT) is an effective noninvasive therapeutic method that employs photosensitizers (PSs) converting oxygen to highly cytotoxic singlet oxygen (1O2) under light irradiation. The conventional PDT efficacy is, however, compromised by the nonspecific delivery of PSs to tumor tissue, the hypoxic tumor microenvironment, and the reduction of generated 1O2 by the intracellular antioxidant glutathione (GSH). Herein, an intelligent multifunctional synergistic nanoplatform (CMGCC) for T1-weighted magnetic resonance (MR) imaging-guided enhanced PDT is presented, which consists of nanoparticles composed of catalase (CAT) and manganese dioxide (MnO2) that are integrated within chlorin-e6-modified glycol chitosan (GC) polymeric micelles. In this system, (1) GC polymers with pH-sensitive surface charge switchability from neutral to positive could improve the PS accumulation within the tumor region, (2) CAT could effectively reoxygenate the hypoxic tumor via catalyzing endogenous hydrogen peroxide to O2, and (3) MnO2 could consume the intracellular GSH while simultaneously producing Mn2+ as a contrast agent for T1-weighted MR imaging. The CMGCC particles possess uniform size distribution, well-defined structure, favorable enzyme activity, and superior 1O2 generation ability. Both in vitro and in vivo experiments demonstrate that the CMGCC exhibit significantly enhanced PDT efficacy toward HeLa cells and subcutaneous HeLa tumors. Our study thereby demonstrates this to be a promising synergistic theranostic nanoplatform with highly efficient PDT performance for cancer therapy.

A Ketogenic Diet Is Protective Against Atherosclerosis in Apolipoprotein E Knockout Mice

Abstract Objectives A ketogenic diet (KD) positively impacts cardiovascular disease (CVD) risk factors yet its effect on atherosclerosis, the main cause of CVD, is elusive. We hypothesize that, when compared to a high-fat diet (HF), KD protects from atherosclerosis. Methods Seven-week-old male Apoe−/− mice, a model for human atherosclerosis, were fed ad libitum (%kcal) KD (81-fat, 1-carbohydrate, 18-protein; n = 4) or HF (40-fat, 42-carbohydrate, 18-protein; n = 5). After 4, 8 and 12 weeks, plasma was collected and used to (1) quantify beta-hydroxybutyrate levels (OH-But) by a colorimetric assay; or (2) assess systemic inflammation, a key feature associated with atherosclerosis, using a panel of inflammatory cytokines; or (3) explore diet-driven changes in levels of atherosclerosis-relevant metabolites using a targeted metabolomic approach by triple quadrupole mass spectrometry. At the endpoint, mice were euthanized and their perfusion-fixed aortas were subjected to 3-D analysis by magnetic resonance imaging to quantify the extent of atherosclerosis. Data were reconstructed using Matlab and segmented to obtain atherosclerotic plaque volumes using Avizo 9.0. Results The inflammatory cytokines were significantly (P &amp;lt; 0.05, Student's t-test) elevated in HF-mice compared to KD-mice after 12 weeks; MIP-1α, (25 ± 13 vs 13 ± 4 pg/mol), MCP-1 (165 ± 67 vs 69 ± 23 pg/mol), TNF-α(51 ± 17 vs 35 ± 5 pg/mol), and IL-1β (2 ± 2 vs 0.6 ± 0.1 pg/mol). OH-But levels were always significantly higher in KD-mice than in HF-mice, thus confirming the presence of ketosis in KD-mice. Significant changes in the plasma metabolome of KD-mice, when compared to HF-mice, were present for dimethylated arginines, gut-derived metabolites, certain bile acids, some acylcarnitines and ceramides, certain sphingolipids and cholesterol esters, and constituents of the major intracellular antioxidant glutathione. Lastly, aortic plaque burden was significantly decreased in KD mice (2.77 ± 1.02%) than in HF mice (13.94 ± 3.72%). Conclusions KD was associated with decreased inflammation, changes in several metabolic intermediates and an atheroprotective effect based on MRI analysis. Funding Sources Huck Institutes of the Life Sciences; Graduate Program in Nutritional Sciences.

Антиоксидант глутатіон підвищує стійкість ядровмісних клітин кордової крові під час кріоконсервування з диметилсульфоксидом

Abstract: The cryopreservation effi ciency of nucleated cells (NCs), in particular hematopoietic progenitor (HPCs) and cord blood (CB) cells was comprehensively assessed in protective mixtures, containing intracellular cryoprotectant dimethyl sulfoxide (DMSO) and antioxidant glutathione in different concentrations assessed immediately after thawing and further transfer to the in vitro conditions, simulating physiological ones. The use of 1 and 3 mM glutathione in cryoprotectant medium with 7.5 and 10% DMSO enabled preserving 85.9 and 91.2% of viable NCs and HPCs, respectively, immediately after thawing and 75–80% of viable NCs/HPCs after 1-hour incubation in the antioxidant-free Hank’s solution, which exceeded the control values. At the same time, the recovery and viability of NCs and HPCs after cryopreservation in 5% DMSO with 1mM or 3 mM glutathione were the same or even higher than those in 7.5 and 10% DMSO without glutathione. The NCs cryopreservation in the glutathione-containing solutions was esta-blished to reduce the number of DCF+ cells. The supplementation of 7.5% DMSO with 1 or 3 mM glutathione reduced the cell number with excess reactive oxygen species from 19% (in glutathione-free samples) to 11% (in glutathione-contained ones), even after transfer to the in vitro conditions, simulating physiological. Probl Cryobiol Cryomed 2020; 30(1): 058–067

Relationship between the antiproliferative properties of Cu(II) complexes with the Schiff base derived from pyridine-2-carboxaldehyde and 5,6-diamino-1,3-dimethyluracil and the redox status mediated by antioxidant defense systems on glioma tumoral cells

A set of new copper(II) complexes containing the Schiff base ligand derived from pyridine-2-carboxaldehyde and 5,6-diamino-1,3-dimethyluracil (6-amino-1,3-dimethyl-5-[(pyridin-2-ylmethylidene)-amino]-pyrimidine-2,4(1H,3H)-dione) with several anions (Cl−, Br−, I−, ClO4−, NO3−) and, two of them with 1,10-phenanthroline, were synthesized and characterized by means of elemental analysis, FT-IR, and single-crystal X-ray diffraction methods. Their ability to act as antitumor agents against C6 glioma cells has been also explored. These complexes contain copper a redox active metal essential for the regulation of cellular pathways that are fundamental for brain function. The antiproliferative activity of the complexes and their effect on cell cycle, apoptosis profile, bioenergetic behavior, intracellular reactive oxygen species (ROS) production, autophagy and enzyme antioxidant defense systems (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities) were analyzed in C6 glioma cells. Although the compounds show limited antiproliferative activity, they are able to modify S-phase of cell cycle and induce G2/M phase arrest. Also, copper(II) complexes promote apoptosis and, in a lesser extent, autophagy, being both processes modulated by ROS generation, due to their property to affect the enzyme antioxidant defense systems, mainly SOD and CAT but not GPx.

CORRECTING GLUTATHIONE DEFICIENCY REVERSES MITOCHONDRIAL DYSFUNCTION AND ACCELERATED AGING IN PATIENTS WITH HIV

Patients with HIV (PWH) have ‘accelerated’ aging based on early manifestation of geriatric comorbidities of declining physical-function, elevated inflammation, insulin-resistance, cognitive-impairment and abdominal-obesity, but contributing mechanisms are not well understood and interventions are lacking. We hypothesized that deficiency of the intracellular-antioxidant Glutathione results in impaired mitochondrial fuel-oxidation (MFO) and contributes to these defects, and that supplementing Glutathione precursors glycine and N-acetylcysteine (GlyNAC) could improve these defects. In an open-label trial, 8 PWH were studied before and after 12-weeks of GlyNAC supplementation (and 8-weeks after stopping GlyNAC), and compared to 8 matched, unsupplemented, uninfected controls. PWH had significantly impaired MFO, abnormal molecular regulation of MFO, muscle Glutathione deficiency, physical decline, cognitive-impairment, and higher oxidative-stress, inflammation, insulin-resistance and total body fat. GlyNAC supplementation significantly improved these defects, but benefits receded on stopping GlyNAC. These data suggest that GlyNAC supplementation could reverse ‘accelerated aging’ in PWH by improving defects linked to impaired MFO.

Chlorinated effluent organic matter causes higher toxicity than chlorinated natural organic matter by inducing more intracellular reactive oxygen species

During unplanned indirect potable reuse, treated wastewater that contains effluent organic matter (EOM) enters the drinking water source, resulting in different toxicity from natural organic matter (NOM) in surface water during chlorination. This study found that, during chlorination, EOM formed more total organic halogen (TOX) and highly toxic nitrogenous disinfection byproducts (DBPs) like dichloroacetonitrile and trichloronitromethane than NOM did. Oxidative stress including both reactive oxygen species (ROS) and reactive nitrogen species (RNS) in Chinese hamster ovary (CHO) cells substantially increased when exposed to chlorinated EOM and chlorinated NOM. The excessive ROS damaged biological macromolecules including DNA, RNA to form 8-hydroxy-(deoxy)guanosine and proteins to form protein carbonyls. Impaired macromolecule further triggered cell cycle arrest at the S and G2 phases, led to cell apoptosis and eventual necrosis. Cytotoxicity and genotoxicity of chlorinated EOM were both higher than those of chlorinated NOM. Adding the blocker L-buthionine-sulfoximine of intracellular antioxidant glutathione demonstrating that oxidative stress might be responsible for toxicity. ROS was further identified to be the main cause of toxicity induction. These findings highlight the risk from chlorinated EOM in the case of unplanned indirect potable reuse, because it showed higher level of cytotoxicity and genotoxicity than chlorinated NOM via inducing more ROS in mammalian cells.

Attenuation of hydrogenperoxide-induced oxidative damages in L929 fibroblast cells by sulfated polysaccharides isolated from the edible marine algae Padina tetrastromatica

Sulfated polysaccharides are polymers with potent biological roles such as antioxidant, anticancer, anti-inflammatory, and immunomodulatory activities. They are gaining significance in advanced healthcare research, since they can control oxidative cellular damages by arresting the reactive oxygen species. Hence, this study aims to evaluate the cellular antioxidant potential of sulfated polysaccharides isolated from the marine algae Padina tetrastromatica in L929 cells. The monosaccharide composition of sulfated polysaccharides was determined using high-performance liquid chromatography. The protective effect of sulfated polysaccharides on L929 fibroblast cells under H2O2-induced oxidative stress has been evaluated using MTT assay, acridine orange/ethidium bromide staining, flow cytometry, comet assay, DCFH-DA staining, fluorometry, and biochemical assays. Sulfated polysaccharides were found to contain glucose, fucose, xylose, and uronic acid. It was non-toxic to L929 cells and effectively increased the viability of mouse fibroblast cells under induced oxidative stress. Various cellular damages such as apoptosis, plasma membrane alterations, DNA damage, and lipid peroxidation induced by H2O2 have been attenuated by sulfated polysaccharides. This might be due to the reduction of intracellular reactive oxygen species level by sulfated polysaccharides as observed in DCFH-DA staining. Sulfated polysaccharides improved the activity of intracellular antioxidant status and glutathione system. The augmentation of endogenous antioxidant enzymes and glutathione system by sulfated polysaccharides can be the possible reason for the reduction of intracellular reactive oxygen species, prevention of apoptosis, and betterment of viability in L929 cells. The study confirms the potent antioxidant activity of the sulfated polysaccharides in addition to their structural and nutritional roles.

Harsh conditions during early development influence telomere length in an altricial passerine: Links with oxidative stress and corticosteroids.

Stress during early development can induce substantial long-term effects in organisms. In the case of birds, despite growth compensations, nestlings reared under harsh conditions typically show reduced survival chances in adulthood. It has been proposed that environmental early-life stressors could affect longevity via effects on telomere length, possibly mediated through oxidative stress. However, the link between these processes is not clear. In this study, we experimentally manipulated brood size in spotless starlings (Sturnus unicolor) to test the causal relationship between early stress, oxidative and corticosterone-mediated stress and telomere shortening. Our results show that experimentally enlarged brood sizes led to a reduction in morphometric development on nestlings, the effect being stronger for females than males. Additionally, basal corticosterone levels increased with increasing brood size in female nestlings. Neither plasma antioxidant status nor malondialdehyde levels (a marker of lipid peroxidation) were affected by experimental brood size, although the levels of a key intracellular antioxidant (glutathione) decreased with increasing brood size. We found that the treatment showed a quadratic effect on nestling telomere lengths: these were shortened either by increases or by decreases in the original brood size. Our study provides experimental evidence for a link between developmental stress and telomere length, but does not support a direct causal link of this reduction with corticosterone or oxidative stress. We suggest that future studies should focus on how telomere length responds to additional markers of allostatic load.

Folate/Vitamin B12 Supplementation Combats Oxidative Stress-Associated Carcinogenesis in a Rat Model of Colon Cancer

Folate and vitamin B12 deficiency is associated with depletion of the major intracellular antioxidant glutathione, and oxidative stress is emerging as an etiological mechanism for colon cancer. Azoxymethane (AOM), a potent carcinogen, induces colon cancer in rats by causing pathophysiological changes and oxidative stress. We investigated the synergistic effect of folate and vitamin B12 supplementation against AOM-induced carcinogenesis and oxidative stress in rat colon. Adult male rats were distributed into four groups: 1) Basal diet only; 2) AOM injection (15 mg/kg once per week in weeks 5 and 6); 3) Folate and vitamin B12 supplemented diet; 4) Folate and B12 diet with AOM injection. After 16 weeks, rats were sacrificed, colon tissue dissected, indicators of oxidative stress were measured, and immunohistochemical and ultrastructural changes were evaluated. AOM-injected rats showed oxidative stress, evident by glutathione depletion, oxidation of cellular proteins, and DNA oxidative damage. AOM increased mucosal levels of antiapoptotic and proapoptotic proteins Bcl2 and Bax and caused ultrastructure changes in colonic cell organelles. Folate and vitamin B12 supplementation decreased the level of oxidative stress and ameliorated the cytotoxic effects of AOM. In this in vivo experimental model of colon cancer, folate and vitamin B12 supplementation combats carcinogen-induced oxidative stress.

Salt-Inducible Kinase 3 Provides Sugar Tolerance by Regulating NADPH/NADP+ Redox Balance

Nutrient-sensing pathways respond to changes in the levels of macronutrients, such as sugars, lipids, or amino acids, and regulate metabolic pathways tomaintain organismal homeostasis [1, 2]. Consequently, nutrient sensing provides animals with the metabolic flexibility necessary for enduring temporal fluctuations in nutrient intake. Recent studies have shown that an animal's ability to survive on a high-sugar diet is determined by sugar-responsive gene regulation [3-8]. It remains to be elucidated whether other levels of metabolic control, such as post-translational regulation of metabolic enzymes, also contribute to organismal sugar tolerance. Furthermore, the sugar-regulated metabolic pathways contributing to sugar tolerance remain insufficiently characterized. Here, we identify Salt-inducible kinase 3 (SIK3), a member of the AMP-activated protein kinase (AMPK)-related kinase family, as a key determinant of Drosophila sugar tolerance. SIK3 allows sugar-feeding animals to increase the reductive capacity of nicotinamide adenine dinucleotide phosphate (NADPH/NADP+). NADPH mediates the reduction of the intracellularantioxidant glutathione, which is essential forsurvival on a high-sugar diet. SIK3 controls NADP+ reduction by phosphorylating and activating Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway. SIK3 gene expression is regulated by the sugar-regulated transcription factor complex Mondo-Mlx, which was previously identified as a key determinant of sugar tolerance. SIK3 converges with Mondo-Mlx in sugar-induced activation of G6PD, and simultaneous inhibition of SIK3 and Mondo-Mlx leads to strong synergistic lethality on a sugar-containing diet. In conclusion, SIK3 cooperates with Mondo-Mlx to maintain organismal sugar tolerance through the regulation of NADPH/NADP+ redox balance.