Activation Of Antioxidant Response Element Research Articles

Protective Effects of Maclurin against Benzo[a]pyrene via Aryl Hydrocarbon Receptor and Nuclear Factor Erythroid 2-Related Factor 2 Targeting.

Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon formed during the incomplete combustion of organic matter, has harmful effects. Therefore, much research is ongoing to develop agents that can mitigate the effects of B[a]P. The aim of this study was to examine the effect of maclurin, one component of the branches of Morus alba L., on the B[a]P-induced effects in HaCaT cells, a human keratinocyte cell line. Maclurin treatment inhibited aryl hydrocarbon receptor (AHR) signaling as evidenced by reduced xenobiotic response element (XRE) reporter activity, decreased expression of cytochrome P450 1A1 (CYP1A1), and reduced nuclear translocation of AHR. The B[a]P-induced dissociation of AHR from AHR-interacting protein (AIP) was suppressed by maclurin. Maclurin also inhibited the production of intracellular reactive oxygen species (ROS) induced by B[a]P. In addition, the antioxidant property of maclurin itself was demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Furthermore, maclurin activated antioxidant response element (ARE) signaling through enhancement of ARE luciferase reporter activity and the expression of ARE-dependent genes including nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1). Nrf2 activation and its nuclear translocation were promoted by maclurin through p38 MAPK activation. These data indicate that maclurin had antagonistic activity against B[a]P effects through activation of Nrf2-mediated signaling and inhibition of AHR signaling and, suggesting its potential in protecting from harmful B[a]P-containing pollutants.

Dietary supplementation with Ceriporia lacerata improves learning and memory in a scopolamine-induced amnesia mouse model.

The online version contains supplementary material available at 10.1007/s10068-021-00945-5.

Optimization of 1,4-bis(arylsulfonamido)naphthalene-N,N'-diacetic acids as inhibitors of Keap1-Nrf2 protein-protein interaction to suppress neuroinflammation

The protein–protein interaction (PPI) between kelch-like ECH-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor 2 (Nrf2) is recognized as a promising target for the prevention and treatment of oxidative stress-related inflammatory diseases. Herein, a series of novel 1,4-bis(arylsulfonamido)naphthalene-N,N'-diacetic acid analogs (7p-t and 8c) were designed to further explore the structure–activity relationships of the series. Their activities were measured first with a fluorescence polarization (FP) assay and more potent compounds were further evaluated using a more sensitive time-resolved fluorescence energy transfer (TR-FRET) assay, demonstrating IC50 values between 7.2 and 31.3 nM. In cytotoxicity studies, the naphthalene derivatives did not show noticeable toxicity to human HepG2-C8 and mouse brain BV-2 microglia cells. Among them, compound 7q bearing oxygen-containing fused rings was shown to significantly stimulate the cellular Nrf2 signaling pathway, including activation of antioxidant response element (ARE)-controlled expression of Nrf2 target genes and proteins. More importantly, 7q suppressed up-regulation of several pro-inflammatory cytokines in lipopolysaccharide (LPS)-challenged BV-2 microglial cells, representing a potential therapeutic application for controlling neuroinflammatory disorders.

Neuroprotective Effects and Mechanisms of Procyanidins In Vitro and In Vivo.

This study evaluated the neuroprotective effects and mechanisms of procyanidins (PCs). In vitro, rat pheochromocytoma cells (PC12 cells) were exposed to PCs (1, 2 or 4 μg/mL) or N-Acetyl-L-cysteine (NAC) (20 μM) for 24 h, and then incubated with 200 μM of H2O2 for 24 h. Compared with H2O2 alone, PCs significantly increased antioxidant activities (e.g., glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT)), decreased levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and increased nuclear factor-erythroid 2-related factor 2 (Nrf2) accumulation and increased the expression of quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1), glutamate-cysteine ligase modifier subunit (GCLM), and glutamate-cysteine ligase catalytic subunit (GCLC). In vivo, zebrafish larvae (AB strain) 3 days post-fertilization (dpf) were exposed to NAC (30 μM) or PCs (4, 8 or 16 μg/mL) in the absence or presence of 300 μM of H2O2 for 4 days. Compared with H2O2 alone, PCs enhanced antioxidant activities (e.g., GSH-Px, CAT, and SOD), decreased levels of ROS and MDA, and enhanced Nrf2/ antioxidant response element (ARE) activation and raised expression levels of NQO1, HO-1, GCLM, and GCLC. In conclusion, these results indicated that PCs exerted neuroprotective effects via activating the Nrf2/ARE pathway and alleviating oxidative damage.

Examination of Novel Immunomodulatory Effects of L-Sulforaphane.

The dietary isothiocyanate L-sulforaphane (LSF), derived from cruciferous vegetables, is reported to have several beneficial biological properties, including anti-inflammatory and immunomodulatory effects. However, there is limited data on how LSF modulates these effects in human immune cells. The present study was designed to investigate the immunomodulatory effects of LSF (10 µM and 50 µM) on peripheral blood mononuclear cell (PBMC) populations and cytokine secretion in healthy adult volunteers (n = 14), in the presence or absence of bacterial (lipopolysaccharide) and viral (imiquimod) toll-like receptor (TLRs) stimulations. Here, we found that LSF reduced pro-inflammatory cytokines interleukin (IL)-6, IL-1β, and chemokines monocyte chemoattractant protein (MCP)-1 irrespective of TLR stimulations. This result was associated with LSF significantly reducing the proportion of natural killer (NK) cells and monocytes while increasing the proportions of dendritic cells (DCs), T cells and B cells. We found a novel effect of LSF in relation to reducing cluster of differentiation (CD) 14+ monocytes while simultaneously increasing monocyte-derived DCs (moDCs: lineage-Human Leukocyte Antigen-DR isotype (HLA-DR)+CD11blow-high CD11chigh). LSF was also shown to induce a 3.9-fold increase in the antioxidant response element (ARE) activity in a human monocyte cell line (THP-1). Our results provide important insights into the immunomodulatory effects of LSF, showing in human PBMCs an ability to drive differentiation of monocytes towards an immature monocyte-derived dendritic cell phenotype with potentially important biological functions. These findings provide insights into the potential role of LSF as a novel immunomodulatory drug candidate and supports the need for further preclinical and phase I clinical studies.

Discovery and SAR studies of 3-amino-4-(phenylsulfonyl)tetrahydrothiophene 1,1-dioxides as non-electrophilic antioxidant response element (ARE) activators

The transcription factor NRF2 controls resistance to oxidative insult and is thus a key therapeutic target for treating a number of disease states associated with oxidative stress and aging. We previously reported CBR-470-1, a bis-sulfone which activates NRF2 by increasing the levels of methylglyoxal, a metabolite that covalently modifies NRF2 repressor KEAP1. Here, we report the design, synthesis, and structure activity relationship of a series of bis-sulfones derived from this unexplored chemical template. We identify analogs with sub-micromolar potencies, 7f and 7g, as well as establish that efficacious NRF2 activation can be achieved by non-toxic analogs 7c, 7e, and 9, a key limitation with CBR-470-1. Further efforts to identify non-covalent NRF2 activators of this kind will likely provide new insight into revealing the role of central metabolism in cellular signaling.

Myricitrin attenuates hypoxic-ischemia-induced brain injury in neonatal rats by mitigating oxidative stress and nuclear factor erythroid 2-related factor 2/hemeoxygenase-1/antioxidant response element signaling pathway

Background: Neonatal hypoxic ischemia (HI) is an overwhelming infantile neurological disability causing extreme morbidity and mortality with limited therapies available. Objectives: In this study, we aimed to explore the neuroprotective efficacy of myricitrin and elucidate the mechanism of action of myricitrin through the regulation of nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1)/antioxidant response element (ARE)-signaling pathways in neonatal rats. Materials and Methods: Seven-day-old neonatal rats were divided into four groups. Sham group served as the control group. After inducing HI through standard operation procedure, two groups of neonatal rats were intraperitoneally administered with 20 and 40 mg/kg bw of myricitrin twice a day for up to 1 week. At the end of the experiment, we assessed the brain infract area, edema, and motor coordination activity by using Rota Rod test. Furthermore, we measured the level of antioxidant enzymes and oxidative stress markers in the brain tissue samples. Real-time quantitative polymerase chain reaction was conducted to detect the inflammatory molecules expression including HO-1 being the activator of Nrf2 where further mediates the transcriptional activation of ARE. Subsequently, the hypothesis was further confirmed by the immunosorbent assay and Western blot analysis. Results: Myricitrin administration ameliorated HI-induced increase in infract volume and edema of the brain, as well as improved neurobehavioral impairments. Interestingly, myricitrin significantly reduced the level of nuclear factor kappa B (NF-κB) p65 and reduced the levels of nuclear fraction of Nrf2-ARE and cytosolic fraction of HO-1 enzyme activation. Conclusion: In summary, myricitrin improved the antioxidant defense mechanism and ameliorated the oxidative stress-associated neurological damage via modulating Nrf2/ARE-dependent HO-1 pathway in neonatal rats.

The anti-UV properties of Saussurea involucrate Matsum. & Koidz. Via regulating PI3K/Akt pathway in B16F10 cells

Ethnopharmacological relevanceUltra Violet (UV) radiation is the major reason for reactive oxygen species (ROS) forming, skin cell damage, melanin production, and could horribly cause skin cancer. Saussureae Involucratae Herba (SIH) is the aerial part of Saussurea involucrata Matsum. & Koidz. This Material Medica is popular with both in Uyghur and Chinese medicines filed. SIH is one of the famous species of the Asteraceae family and which prescribed for skin protection from UV-induced damage according to China Pharmacopeia (2020). However, the detailed working mechanism involved is still not elucidated. Aim of the studyWe would like to probe the potential transduction pathway of SIH against UV-induced skin cell damages in cultured B16F10 cells. MethodsWestern blot, luciferase assay, laser confocal, RT-PCR and flow cytometer were employed here to verify the protective pharmaceutical value of SIH in cultured B16F10 cells after UV pre-treatment. ResultsOur result revealed that SIH attenuates ROS formation after UV-induced damage in B16F10 cells in a dose-dependent manner. Moreover, the transcriptional and translational anti-oxidative encoding genes were up-regulated under the presence of SIH. Further studies showed that SIH activated transcriptional activity of anti-oxidant response element (ARE). Moreover, we found that SIH dramatically stimulates PI3K/Akt phosphorylation in cultured B16F10 cells, this result was further verified by its specific inhibitors, LY294002 and Tocris. ConclusionOur findings concluded that SIH protect melanoma cells from UV damages via activating PI3K/Akt signaling and which could provide scientific evidence for anti-UV pharmaceutical values of this herbal extract.

Astragaloside IV, a saponin from Astragalus membranaceus var. mongholicus, induces expressions of heme recycle proteins via signaling of Nrf2/ARE in cultured macrophages

Ethnopharmacological relevanceIn traditional Chinese medicine (TCM) theory, “Qi” is classified as energetic essence supporting the life activities in human. “Blood” is categorized as nourishing essence and circulating in the body. “Blood” and “Qi” have an intimate relationship. Astragali Radix (AR; root of Astragalus membranaceus (Fisch.) Bge. Var. mongholicus (Bge.) Hsiao) has a broad spectrum of application for “Qi-Blood” enrichment. Astragaloside IV, a major saponin in AR, has therapeutic functions in erythropoietic, cardiovascular and immune systems. However, the efficacy of astragaloside IV in erythrophagocytosis has not been elucidated. Aim of the studyThe possible functions of astragaloside IV in heme iron recycling during erythrophagocytosis in cultured macrophage were elucidated. MethodsThe translational and transcriptional expressions of heme recycling enzymes were determined after incubating of astragaloside IV for 24 h in cultured macrophage. ResultsIn astragaloside IV-treated macrophage, the expressions, both RNA and protein levels, of regulators of heme recycling, e.g. heme oxygenase-1 (HO-1), ferroportin (FPN), biliverdin reductase A and B (BVRA, BVRB), were markedly induced in dose-dependent manners. In parallel, the transcriptional activity of antioxidant response element, cloned within an expression vector as pARE-Luc and transfected in cultured macrophages, was markedly induced after a challenge with astragaloside IV in a dose-dependent manner. Moreover, the translocation of Nrf2, a transcriptional factor in regulating expression of heme recycling protein, was induced by astragaloside IV, leading to an enrichment at nucleus fraction. ConclusionAstragaloside IV shed lights in enhancing the expression of heme recycle proteins via Nrf2/ARE signaling pathway.

Protective effects of Nrf2–ARE activator on dopaminergic neuronal loss in Parkinson disease model mice: Possible involvement of heme oxygenase-1

Parkinson disease (PD) is a neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra, and oxidative stress is thought to contribute to this pathogenesis. The nuclear factor erythroid 2-related factor 2 (Nrf2)–antioxidant response element (ARE) pathway, which induces the production of antioxidant enzymes, is thereby a potential target for therapeutics to reduce neurodegeneration in PD. Previously, we identified TPNA10168 from a chemical library as an activator of the Nrf2–ARE pathway, and the present study examined the effects of TPNA10168 on an in vivo PD model. Subcutaneous administration of TPNA10168 was associated with inhibited dopaminergic neuronal loss and behavioral impairment in 6-hydroxydopamine–induced PD model mice. Heme oxygenase-1 (HO-1) is an antioxidant enzyme expressed downstream of the Nrf2–ARE signaling pathway, and we observed that HO-1 protein levels were upregulated by TPNA10168 in the mouse brain. These results suggest that TPNA10168 inhibits dopaminergic neuronal death in PD model mice, and that upregulation of HO-1 might participate in this effect.

Antioxidant response element activator, BTZO-1, improves the developmental competence of bovine oocytes.

Increased reactive oxygen species (ROS) generation may disrupt the oocytes function and their competence. In this study, we introduced BTZO-1, a new supplement that can regulate the oxidative stress. Addition of BTZO-1 during IVM of bovine oocytes improved their developmental competence in the term of improvement of blastocyst rates. In addition, the quality of the produced embryos was improved by decreasing the apoptosis level by showing a decreased number of TUNNEL positive cells.

Chemical and Biological Characterization of Particulate Matter (PM 2.5) and Volatile Organic Compounds Collected at Different Sites in the Los Angeles Basin

Background: Most studies on air pollution (AP) exposure have focused on adverse health effects of particulate matter (PM). Less well-studied are the actions of volatile organic compounds (VOCs) not retained in PM collections. These studies quantified chemical and biological properties of both PM2.5 and VOCs. Methods: Samples were collected near the Port of Los Angeles (Long Beach, LB), railroads (Commerce, CM), and a pollution-trapping topography-site (San Bernardino, SB). Quantitative assays were conducted: (1) chemical—prooxidant and electrophile content, (2) biological—tumor necrosis factor-α (TNF-α) and heme oxygenase-1 (HO-1) expression (3), VOC modulation of PM effects and (4), activation of the antioxidant response element (ARE) using murine RAW 264.7 macrophages. Results: SB site samples were the most potent in the chemical and biological assays, followed by a CM railroad site. Only PM2.5 exhibited significant proinflammatory responses. VOCs were more potent than PM2.5 in generating anti-inflammatory responses; further, VOC pretreatment reduced PM-associated TNF-α expression. VOCs significantly increased ARE activation compared to their corresponding PM2.5 which remained at background levels. Conclusion: Ambient VOCs are major contributors to adaptive responses that can modulate PM effects, in vitro, and, as such, need to be included in comprehensive assessments of AP.

α-Sens: The improved ARE-Nrf2-based sensitization screening assay using normalized transcriptional activity

Two non-animal test methods, KeratinoSens™ and LuSens, have been approved by the Organization of Economic Cooperation and Development (OECD) test guidelines for evaluating the sensitization potential of chemicals, and been positioned as a method for appraising key event (KE)-2, namely, the keratinocyte response component of the Adverse Outcome Pathway (AOP) in sensitization process. However, these two methods require separate cytotoxicity tests to determine the concentrations to be tested in the main test. Therefore, we developed a simple and highly accurate KE-2 test method named α-Sens that uses the dual luciferase assay system and attempted a further application of luciferase-based determination of cell viability to calculate the normalized Antioxidant response element (ARE)-mediated transcriptional activity, named normalized ARE Activity (nAA), to evaluate the sensitizing potential of chemicals. A cell line carrying the ARE-inducible Firefly luciferase reporter gene and Thymidine kinase (TK) promoter-driven Renilla luciferase gene was established and used for the α-Sens. A total of 28 chemicals, consisting of 19 skin sensitizers and nine non-skin sensitizers were tested by this assay system. The α-Sens yielded an accuracy (%), sensitivity (%), and specificity (%) against corresponding values for local lymph node assay of 96.4 %, 95.0 %, and 100 %, respectively, and for human data of 100 % for all. The α-Sens gave clear positive results for phenyl benzoate and eugenol, chemicals for which KeratinoSens™ or LuSens yielded false-negative results, using a new parameter. Our results suggest that better prediction capacity could be achieved by using nAA as a classifier compared to other existing KE-2 test methods. In conclusion, the α-Sens is promising as a simple and highly accurate in vitro skin sensitization test method for evaluation of KE-2.

Copper Oxide Nanoparticles Activate Nrf2, KEAP 1, and Downstream Target Genes in JB6 Cells possibly through ROS Generation and Antioxidant Response Element (ARE) Mechanisms

Occupational exposures to Copper Oxide (CuO) nanoparticles havebeen reported to be harmful to human health, with possible risk of cancer amongworkers from many sectors. CuOnanoparticles have not, to our knowledge, been extensively examined forpotential carcinogenic toxicological effects. To investigate the mechanisms ofCuO‐induced pathogenesis, the effect of metal oxide fine and nanoparticles on antioxidantresponse mechanisms and ROS generation were investigated. The results indicated that CuO caused a2‐fold increase in AP‐1 activity in JB6 cells. The induction of AP‐1 activityin cultured cell lines was time and dose‐dependent. The signal transductionpathways for AP‐1 activation were also investigated. Western Blot analysisdemonstrate that CuO nanoparticles stimulate phosphorylation of p38 MAPK andERKs. CuO also generated ROS whenincubated with the cells as measured by electron spin resonance (ESR). Nano‐sized CuO generated more ROS than thefine sized particles when incubated with the cells. COMET assay suggests thatexposure of the cells to CuO resulted in DNA damage. Cells pre‐treated with ROSinhibitors sodium formate and Polyvinylpyridine‐N‐Oxide (PVPNO) before exposureto CuO nanoparticles demonstrate a significant reduction in p‐38 and ERKactivity, suggesting the H2O2 may have a role in the ROSmechanism. CuO Nanoparticles induced Nrf2 translocation and activation in adose and time‐dependent manner. Glutathione S‐transferase and NAD(P)H:quinoneoxidoreductase 1(NQO1) were increased in a time‐dependent manner following JB6exposure to CuO nanoparticles. Unraveling the complex mechanisms associatedwith these events suggests that activation of Nrf2 and subsequent activation ofthe ARE by ROS generation may contribute to adverse health effects followingexposure to CuO nanoparticles.Support or Funding InformationThis project was supported by a grant from the Nanotechnology Research Center.

Involvement of Nrf2 and Keap1 in the activation of antioxidant responsive element (ARE) by chemopreventive agent peptides from soft-shelled turtle

The antioxidant response element (ARE) is a cis-acting enhancer sequence located in the region containing genes related to antioxidant and detoxification. Under oxidative stress, the induction of nuclear factor-E2-related factor 2 (Nrf2)/ARE is considered as a fundamental process involved in defending reactive oxygen species (ROS) and providing protection against toxic xenobiotics. In this study, we obtained seven antioxidant peptides from soft-shelled turtle and concluded that Glu-Asp-Tyr-Gly-Ala (EDYGA) is the most potent ARE-luciferase inducer. To gain fundamental insights into the role of EDYGA in oxidative stress, we evaluated the effects of EDYGA on the Nrf2/Keap1 system in HepG2 cells. The results revealed that EDYGA modulated the Nrf2/ARE pathway by enhancing Nrf2 level through the stabilization of Nrf2, which was accomplished by a decrease in the level of Keap1. These actions eventually led to an increase in nuclear Nrf2 accumulation and ARE-binding activity. Moreover, silencing Nrf2 markedly reduced ARE-driven activity induced by EDYGA. Docking results proved that glutamate residues of peptide EDYGA directly bind to Arg 415 of Kelch domain receptor pocke. The results were helpful in understanding the antioxidant activity of peptides from soft-shelled turtle which have potential to be used in foods and drugs as functional ingredients.

Pioglitazone Attenuates Lipopolysaccharide-Induced Oxidative Stress, Dopaminergic Neuronal Loss and Neurobehavioral Impairment by Activating Nrf2/ARE/HO-1.

The aim of the present study was to examine the neuroprotective potential of pioglitazone via activation of Nrf2/ARE-dependent HO-1 signaling pathway in chronic neuroinflammation and progressive neurodegeneration mouse model induced by lipopolysaccharide (LPS). After assessing spatial memory, anxiety and motor-coordination, TH+ neurons in substantia nigra (SN) were counted. The oxidative stress marker carbonyl protein levels and HO-1 enzyme activity were also evaluated. RT-qPCR was conducted to detect HO-1, Nrf2 and NF-κp65 mRNA expression levels and Nrf2 transcriptional activation of antioxidant response element (ARE) of HO-1 was investigated. Pioglitazone ameliorated LPS-induced dopaminergic neuronal loss, as well as mitigated neurobehavioral impairments. It enhanced Nrf2 mRNA expression, and augmented Nrf2/ARE-dependent HO-1 pathway activation by amplifying HO-1 mRNA expression. Moreover, it induced a significant decrease in NF-κB p65 mRNA expression, while reducing carbonyl protein levels and restoring the HO-1 enzyme activity. Interestingly, LPS induced Nrf2/antioxidant response element (ARE) of HO-1 activation, ultimately resulting in slight enhanced HO-1 mRNA expression. However, LPS elicited decrease in HO-1 enzyme activity. Zinc protoporphyrin-IX (ZnPPIX) administrated with pioglitazone abolished its effects in the LPS mouse model. The study results demonstrate that coordinated activation of Nrf2/ARE-dependent HO-1 pathway defense mechanism by the PPARγ agonist pioglitazone mediated its neuroprotective effects.

Antagonizing Effects of Clematis apiifolia DC. Extract against Benzo[a]pyrene-Induced Damage to Human Keratinocytes.

Background. Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon present in the atmosphere, has cytotoxic and carcinogenic effects. There have been no reports to demonstrate involvement of Clematis apiifolia DC. extract (CAE) in B[a]P-induced effects. This study was conducted to investigate the effect of CAE on B[a]P-induced effects and to elucidate its mechanism of action in HaCaT human keratinocytes. CAE inhibited aryl hydrocarbon receptor (AhR) signaling by decreasing both XRE reporter activity and expression of cytochrome P450 1A1 (CYP1A1) induced by B[a]P treatment in HaCaT cells. We also found that B[a]P-induced nuclear translocation of AhR and production of reactive oxygen species (ROS) and proinflammatory cytokines were attenuated by CAE treatment. CAE treatment suppressed B[a]P-induced phosphorylation of Src (Tyr416). In addition, dasatinib, a Src inhibitor, also inhibited B[a]P-induced nuclear translocation of AhR, similar to CAE treatment. In addition, CAE activated antioxidant response element (ARE) signaling by increasing ARE luciferase reporter activity and expression of ARE-dependent genes such as nuclear factor (erythroid-derived 2)-like 2 (Nrf2), NAD(P)H dehydrogenase [quinone] 1 (NQO1), and heme oxygenase-1 (HO-1). Nuclear translocation of Nrf2 by CAE was demonstrated by Western blot analysis and immunocytochemistry. The effects of CAE on ARE signaling were attenuated by knockdown of the Nrf2 gene. Inhibition of AhR signaling and activation of antioxidant activity by CAE operated in a reciprocally independent manner as evidenced by AhR and Nrf2 siRNA experiments. These findings indicate that CAE exerts protective effects against B[a]P by inhibiting AhR signaling and activating Nrf2-mediated signaling, suggesting its potential in protection from harmful B[a]P-containing pollutants.

Zingerone attenuates aortic banding-induced cardiac remodelling via activating the eNOS/Nrf2 pathway.

Cardiac remodelling refers to a series of changes in the size, shape, wall thickness and tissue structure of the ventricle because of myocardial injury or increased pressure load. Studies have shown that cardiac remodelling plays a significant role in the development of heart failure. Zingerone, a monomer component extracted from ginger, has been proven to possess various properties including antioxidant, anti‐inflammatory, anticancer and antidiabetic properties. As oxidative stress and inflammation contribute to acute and chronic myocardial injury, we explored the role of zingerone in cardiac remodelling. Mice were subjected to aortic banding (AB) or sham surgery and then received intragastric administration of zingerone or saline for 25 days. In vitro, neonatal rat cardiomyocytes (NRCMs) were treated with zingerone (50 and 250 μmol/L) when challenged with phenylephrine (PE). We observed that zingerone effectively suppressed cardiac hypertrophy, fibrosis, oxidative stress and inflammation. Mechanistically, Zingerone enhanced the nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2)/antioxidant response element (ARE) activation via increasing the phosphorylation of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) production. Additionally, we used Nrf2‐knockout (KO) and eNOS‐KO mice and found that Nrf2 or eNOS deficiency counteracts these cardioprotective effects of zingerone in vivo. Together, we concluded that zingerone may be a potent treatment for cardiac remodelling that suppresses oxidative stress via the eNOS/Nrf2 pathway.

Neuroprotective effects of Brazilian green propolis on oxytosis/ferroptosis in mouse hippocampal HT22 cells

Propolis is a sticky dark-colored substance produced by honey bees and comprises resin, balsam, wax, essential and aromatic oils, pollen, and several other substances; it is used in food and beverages to improve health and prevent diseases. We studied the neuroprotective effects of extracts of Brazilian green propolis in the mouse hippocampal cell line HT22. Ethanol extracts of Brazilian green propolis had a more potent preventive effect on oxidative stress-induced cell death, oxytosis/ferroptosis, in HT22 cells than water extracts of Brazilian green propolis, whereas it did not protect against anticancer drug-induced apoptotic cell death. Among the primary constituents of ethanol extracts of Brazilian green propolis, only artepillin C, kaempferide, and kaempferol demonstrated neuroprotective effects against oxytosis/ferroptosis. The flavonoid derivatives kaempferide and kaempferol are antioxidants with radical-scavenging abilities that additionally induce antioxidant response element-mediated transcriptional activity, suggesting that upregulation of endogenous antioxidant defense protects against oxidative stress. In contrast, artepillin C attenuated reactive oxygen species production; however, it did not induce antioxidant response element activation. These findings indicate that the ethanol extracts of Brazilian green propolis help to prevent oxidative stress-related neuronal cell death that is involved in the pathogenesis of several neurodegenerative diseases.

Repression of Nrf2/ARE regulated antioxidant genes and dysregulation of the cellular redox environment by the HIV Transactivator of Transcription

Chronic HIV infection in the era of anti-retroviral therapy is associated with dramatically increased risk of developing severe cardio pulmonary disease. Common to these diseases is increased oxidative burden and chronic inflammation despite low viremia and restoration of CD4+ T-cell levels. Soluble viral factors are heavily implicated in these disease processes, including the HIV Transactivator of Transcription (Tat). Tat is produced in high levels during infection and secreted from infected cells into circulation where it is internalized by bystander cells and is known to regulate inflammatory pathways and elicit a pro-oxidant environment. We have examined the effects of Tat on the anti-oxidant regulatory network driven by the transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in primary human pulmonary arterial endothelial cells, which are heavily involved in pathogenesis of HIV associated lung diseases including pulmonary arterial hypertension and COPD. Co-expression of Tat and a luciferase reporter construct driven by the Nrf2 activated anti-oxidant response element (ARE) demonstrated markedly reduced Nrf2/ARE activity, even when stimulated by the potent Nrf2 activating compound PB125. Additionally, Heme-oxygenase-1 (HO-1) transcription was potently repressed by Tat in a cell line as well as primary endothelial cells, and treatment with PB125 failed to restore transcriptional activity. Other anti-oxidant Nrf2 genes examined included NADPH Dehydrogenase Quinone 1 (NQO1) and Sulfiredoxin-1 (SRXN1). NQO1 was repressed basally by Tat, while SRXN1 transcription was refractory to activation by PB125 in the presence of Tat. Lastly, we demonstrated that Tat expressing cells have increased indicators of oxidative stress including elevated production of reactive oxygen species, measured by electron paramagnetic resonance spectroscopy, and increased levels of nitrotyrosine content. These observations suggest a novel mechanism by which HIV Tat increases oxidative burden by dysregulation of the Nrf2/ARE pathway.