Manganese superoxide dismutase, MnSOD and its mimics

Dioxygen Reactivity of Copper(I)/Manganese(II)-Porphyrin Assemblies: Mechanistic Studies and Cooperative Activation of O2

The oxidation of transition metals such as manganese and copper by dioxygen (O₂) is of great interest to chemists and biochemists for fundamental and practical reasons. In this report, the O₂ reactivities of 1:1 and 1:2 mixtures of [(TPP)Mn^II] (1; TPP: Tetraphenylporphyrin) and [(tmpa)Cu^I(MeCN)]⁺ (2; TMPA: Tris(2-pyridylmethyl)amine) in 2-methyltetrahydrofuran (MeTHF) are described. Variable-temperature (-110 °C to room temperature) absorption spectroscopic measurements support that, at low temperature, oxygenation of the (TPP)Mn/Cu mixtures leads to rapid formation of a cupric superoxo intermediate, [(tmpa)Cu^II(O₂^•-)]⁺ (3), independent of the presence of the manganese porphyrin complex (1). Complex 3 subsequently reacts with 1 to form a heterobinuclear μ-peroxo species, [(tmpa)Cu^II-(O₂^2-)-Mn^III(TPP)]⁺ (4; λ_max = 443 nm), which thermally converts to a μ-oxo complex, [(tmpa)Cu^II-O-Mn^III(TPP)]⁺ (5; λ_max = 434 and 466 nm), confirmed by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. In the 1:2 (TPP)Mn/Cu mixture, 4 is subsequently attacked by a second equivalent of 3, giving a bis-μ-peroxo species, i.e., [(tmpa)Cu^II-(O₂^2-)-Mn^IV(TPP)-(O₂^2-)-Cu^II(tmpa)]²⁺ (7; λ_max = 420 nm and δ_pyrrolic = -44.90 ppm). The final decomposition product of the (TPP)Mn/Cu/O₂ chemistry in MeTHF is [(TPP)Mn^III(MeTHF)₂]⁺ (6), whose X-ray structure is also presented and compared to literature analogs.

In Situ Synthesis of Natural Antioxidase Mimics for Catalytic Anti-Inflammatory Treatments: Rheumatoid Arthritis as an Example

Mimicking the coordination geometry of the active metal sites of natural enzymes is an efficient strategy in designing therapeutic chemicals with enzymelike in vivo reaction thermodynamics and kinetics. In this study, this chemical concept has been applied for the in situ synthesis of natural antioxidase mimics for catalytic anti-inflammatory treatment by using rheumatoid arthritis, a common and hardly curable immune-mediated diseases, as an example. Briefly, a composite nanomedicine has been first constructed by loading cationic porphyrin ligands into a manganese-engineered mesoporous silica nanocarrier, which can respond to a mildly acidic environment to concurrently release manganous ions and porphyrin ligands, enabling their subsequent coordination and synthesis of manganese porphyrin with a coordination environment of an active Mn site similar to those of the metal sites in natural superoxide dismutase (SOD) and catalase. Due to the strong metal-ligand exchange coupling enabled by the N-ethylpyridinium-2-yl groups tetrasubstituted in the meso positions of N4-macroheterocycles, such a manganese porphyrin presents the SOD-like activity of disproportionating superoxide anions via outer-sphere proton-coupled one-electron transfer (diaquamanganese(III)/monoaquamanganese(II) cycling), as well as the catalase-like activity of disproportionating hydrogen peroxide via inner-sphere proton-coupled two-electron transfer (diaquamanganese(III)/dioxomanganese(V) cycling). Cellular experiments demonstrated the high antioxidative efficacy of the composite nanomedicine in M1 macrophages by promoting their polarization shift to the anti-inflammatory M2 phenotype. Equally importantly, the silicon-containing oligomers released from the manganese silicate nanocarrier can act as heterogeneous nucleation centers of hydroxyapatite for facilitating biomineralization by bone mesenchymal stem cells. Finally, an in vivo adjuvant-induced arthritis animal model further reveals the high efficacy of the nanomedicine in treating rheumatoid arthritis.

Cryotrapping peroxide in the active site of human mitochondrial manganese superoxide dismutase crystals for neutron diffraction

Structurally identifying the enzymatic intermediates of redox proteins has been elusive due to difficulty in resolving the H atoms involved in catalysis and the susceptibility of ligand complexes to photoreduction from X-rays. Cryotrapping ligands for neutron protein crystallography combines two powerful tools that offer the advantage of directly identifying hydrogen positions in redox-enzyme intermediates without radiolytic perturbation of metal-containing active sites. However, translating cryogenic techniques from X-ray to neutron crystallography is not straightforward due to the large crystal volumes and long data-collection times. Here, methods have been developed to visualize the evasive peroxo complex of manganese superoxide dismutase (MnSOD) so that all atoms, including H atoms, could be visualized. The subsequent cryocooling and ligand-trapping methods resulted in neutron data collection to 2.30 Å resolution. The P6122 crystal form of MnSOD is challenging because it has some of the largest unit-cell dimensions (a = b = 77.8, c = 236.8 Å) ever studied using high-resolution cryo-neutron crystallography. The resulting neutron diffraction data permitted the visualization of a dioxygen species bound to the MnSOD active-site metal that was indicative of successful cryotrapping.

Unveiling Endophytic Bacterial Community Structures of Different Rice Cultivars Grown in a Cadmium-Contaminated Paddy Field

Endophytic bacteria play potentially important roles in the processes of plant adaptation to the environment. Understanding the composition and dynamics of endophytic bacterial communities under heavy metal (HM) stress can reveal their impacts on host development and stress tolerance. In this study, we investigated root endophytic bacterial communities of different rice cultivars grown in a cadmium (Cd)-contaminated paddy field. These rice cultivars are classified into low (RBQ, 728B, and NX1B) and high (BB and S95B) levels of Cd-accumulating capacity. Our metagenomic analysis targeting 16S rRNA gene sequence data reveals that Proteobacteria, Firmicutes, Actinobacteria, Acidobacteria, Bacteroidetes, and Spirochaetes are predominant root endophytic bacterial phyla of the five rice cultivars that we studied. Principal coordinate analysis shows that the developmental stage of rice governs a larger source of variation in the bacterial communities compared to that of any specific rice cultivar or of the root Cd content. Endophytic bacterial communities during the reproductive stage of rice form a more highly interconnected network and exhibit higher operational taxonomic unit numbers, diversities, and abundance than those during the vegetative stage. Forty-five genera are significantly correlated with Cd content in rice root, notably including positive-correlating Geobacter and Haliangium; and negative-correlating Pseudomonas and Streptacidiphilus. Furthermore, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis shows that functional pathways, such as biosynthesis of siderophore and type II polyketide products, are significantly enhanced during the reproductive stage compared to those during the vegetative stage under Cd stress. The isolated endophytic bacteria from the Cd-contaminated rice roots display high Cd resistance and multiple traits that may promote plant growth, suggesting their potential application in alleviating HM stress on plants. This study describes in detail for the first time the assemblage of the bacterial endophytomes of rice roots under Cd stress and may provide insights into the interactions among endophytes, plants, and HM contamination.

Bioinspired mononuclear Mn complexes for O2 activation and biologically relevant reactions

A general interest in harnessing the oxidizing power of dioxygen (O₂) continues to motivate research efforts on bioinspired and biomimetic complexes to better understand how metalloenzymes mediate these reactions. The ubiquity of Fe- and Cu-based enzymes attracts significant attention and has resulted in many noteworthy developments for abiotic systems interested in direct O₂ reduction and small molecule activation. However, despite the existence of Mn-based metalloenzymes with important O₂-dependent activity, there has been comparatively less focus on the development of these analogues relative to Fe- and Cu-systems. In this Perspective, we summarize important contributions to the development of bioinspired mononuclear Mn complexes for O₂ activation and studies on their reactivity, emphasizing important design parameters in the primary and secondary coordination spheres and outlining mechanistic trends.

Common Inflammatory Mechanisms in COVID-19 and Parkinson's Diseases: The Role of Microbiome, Pharmabiotics and Postbiotics in Their Prevention

In the last decade, metagenomic studies have shown the key role of the gut microbiome in maintaining immune and neuroendocrine systems. Malfunction of the gut microbiome can induce inflammatory processes, oxidative stress, and cytokine storm. Dysfunction of the gut microbiome can be caused by short-term (virus infection and other infectious diseases) or long-term (environment, nutrition, and stress) factors. Here, we reviewed the inflammation and oxidative stress in neurodegenerative diseases and coronavirus infection (COVID-19). Here, we reviewed the renin-angiotensin-aldosterone system (RAAS) involved in the processes of formation of oxidative stress and inflammation in viral and neurodegenerative diseases. Moreover, the coronavirus uses ACE2 receptors of the RAAS to penetrate human cells. The coronavirus infection can be the trigger for neurodegenerative diseases by dysfunction of the RAAS. Pharmabiotics, postbiotics, and next-generation probiotics, are considered as a means to prevent oxidative stress, inflammatory processes, neurodegenerative and viral diseases through gut microbiome regulation.

Association of GSTO1, GSTO2, GSTP1, GPX1 and SOD2 polymorphism with primary open angle glaucoma

It is becoming increasingly evident that oxidative stress has a supporting role in pathophysiology and progression of primary open angle glaucoma (POAG). The aim of our study was to assess the association between polymorphisms in genes encoding enzymes involved in redox homeostasis, mitochondrial superoxide dismutase (SOD2), glutathione peroxidase (GPX1) and glutathione transferases (GSTs) with susceptibility to POAG. Single nucleotide polymorphisms in GST omega (GSTO1rs4925, GSTO2 rs156697), pi 1 (GSTP1 rs1695), as well as GPX1 (rs1050450) and SOD2 (rs4880) were determined by quantitative polymerase chain reaction (qPCR) in 102 POAG patients and 302 respective controls. The risk for POAG development was noted in carriers of both GSTO2*GG and GSTO1*AA variant genotypes (OR = 8.21, p = 0.002). Individuals who carried GPX1*TT and SOD2*CC genotypes had also an increased risk of POAG development but without significance after Bonferroni multiple test correction (OR = 6.66, p = 0.005). The present study supports the hypothesis that in combination, GSTO1/GSTO2, modulate the risk of primary open angle glaucoma.

Influence of Zinc and Manganese Nanoparticles on Selected Parameters of Turkey Spermatozoa Stored in a Liquid State at 4 °C

The aim of this study was to determine the effect of semen extender supplementation with 25 or 50 μM of zinc nanoparticles (ZnNPs) or manganese nanoparticles (MnNPs) on turkey spermatozoa preserved in a liquid state. Twenty turkey ejaculates were obtained from twenty healthy males. The collected semen was preserved at 4 °C for 48 h with or without NPs. Selected qualitative and quantitative parameters of sperm (motility, plasma membrane activity, mitochondrial membrane potential (MMP) and the percentage of sperm demonstrating NO and SOD activity) were examined after 2, 24 and 48 h of storage. Sperm motility and MMP decreased in semen preserved with ZnNPs at each time point of the analysis. However, all spermatozoa remained viable throughout storage. In contrast, membrane integrity and mitochondria activity (p ≤ 0.05) increased, and the highest SOD activity (p ≤ 0.05) was observed in semen preserved with MnNPs. The addition of MnNPs to the semen extender could potentially improve the parameters of turkey semen during prolonged storage.

Optimization, Characterization and Pharmacokinetic Study of Meso-Tetraphenylporphyrin Metal Complex-Loaded PLGA Nanoparticles

The selection of technological parameters for nanoparticle formulation represents a complicated development phase. Therefore, the statistical analysis based on Box-Behnken methodology is widely used to optimize technological processes, including poly(lactic-co-glycolic acid) nanoparticle formulation. In this study, we applied a two-level three-factor design to optimize the preparation of nanoparticles loaded with cobalt (CoTPP), manganese (MnClTPP), and nickel (NiTPP) metalloporphyrins (MeP). The resulting nanoparticles were examined by dynamic light scattering, X-ray diffraction, Fourier transform infrared spectroscopy, MTT test, and hemolytic activity assay. The optimized model of nanoparticle formulation was validated, and the obtained nanoparticles possessed a spherical shape and physicochemical characteristics enabling them to deliver MeP in cancer cells. In vitro hemolysis assay revealed high safety of the formulated MeP-loaded nanoparticles. The MeP release demonstrated a biphasic profile and release mechanism via Fick diffusion, according to release exponent values. Formulated MeP-loaded nanoparticles revealed significant antitumor activity and ability to generate reactive oxygen species. MnClTPP- and CoTPP-nanoparticles specifically accumulated in tissues, preventing wide tissue distribution caused by long-term circulation of the hydrophobic drug. Our results suggest that MnClTPP- and CoTPP-nanoparticles represent the greatest potential for utilization in in anticancer therapy due to their effectiveness and safety.

An organometallic catalase mimic with exceptional activity, H2O2 stability, and catalase/peroxidase selectivity

Manganese-porphyrin and -salen redox therapeutics catalyze redox reactions involving O2˙-, H2O2, and other reactive oxygen species, thereby modulating cellular redox states. Many of these complexes perform catalase reactions via high-valent Mn-oxo or -hydroxo intermediates that oxidize H2O2 to O2, but these intermediates can also oxidize other molecules (e.g., thiols), which is peroxidase reactivity. Whether catalase or peroxidase reactivity predominates depends on the metal-ligand set and the local environment, complicating predictions of what therapeutic effects (e.g., promoting vs. suppressing apoptosis) a complex might produce in a given disease. We recently reported an organoruthenium complex (Ru1) that catalyzes ABTS˙- reduction to ABTS2- with H2O2 as the terminal reductant. Given that H2O2 is thermodynamically a stronger oxidant than ABTS˙-, we reasoned that the intermediate that reduced ABTS˙- would also be able to reduce H2O2 to H2O. Herein we demonstrate Ru1-catalyzed H2O2 disproportionation into O2 and H2O, exhibiting an 8,580-fold faster catalase TOF vs. peroxidase TOF, which is 89.2-fold greater than the highest value reported for a Mn-porphyin or -salen complex. Furthermore, Ru1 was 120-fold more stable to H2O2 than the best MnSOD mimic (TON = 4000 vs. 33.4) Mechanistic studies provide evidence that the mechanism for Ru1-catalyzed H2O2 disproportionation is conserved with the mechanism for ABTS˙- reduction. Therapeutic effects of redox catalysts can be predicted with greater accuracy for catalysts that exhibit exclusively catalase activity, thereby facilitating the development of future redox therapeutic strategies for diseases.

Associations of Habitual Mineral Intake with New-Onset Prediabetes/Diabetes after Acute Pancreatitis

Associations between habitual dietary intake of minerals and glucose metabolism have been extensively studied in relation to metabolic disorders. However, similar research has yet to be conducted in individuals after acute pancreatitis (AP). The main aim was to investigate the associations between habitual intake of 13 minerals and glycaemic status: new-onset prediabetes/diabetes after AP (NODAP), pre-existing prediabetes/type 2 diabetes (T2DM), and normoglycaemia after AP (NAP). Associations between the dietary intake of minerals and markers of glucose metabolism (glycated haemoglobin and fasting plasma glucose) were also studied. The EPIC-Norfolk food frequency questionnaire was used in a cross-sectional fashion to determine the habitual intake of 13 dietary minerals. ANCOVA as well as multiple linear regression analyses were conducted and five statistical models were built to adjust for covariates. The study included 106 individuals after AP. In the NODAP group, intake of 4 minerals was significantly less when compared with the NAP group: iron (B = -0.076, p = 0.013), nitrogen (B = -0.066, p = 0.003), phosphorous (B = -0.046, p = 0.006), and zinc (B = -0.078, p = 0.001). Glycated haemoglobin was significantly associated with iodine intake (B = 17.763, p = 0.032) and manganese intake (B = -17.147, p = 0.003) in the NODAP group. Fasting plasma glucose was significantly associated with manganese intake (B = -2.436, p = 0.027) in the NODAP group. Habitual intake of minerals differs between individuals with NODAP, T2DM, and NAP. Prospective longitudinal studies and randomised controlled trials are now warranted to further investigate the associations between mineral intake and NODAP.

Interplay between Mitochondrial Metabolism and Cellular Redox State Dictates Cancer Cell Survival

Mitochondria are the main powerhouse of the cell, generating ATP through the tricarboxylic acid cycle (TCA) and oxidative phosphorylation (OXPHOS), which drives myriad cellular processes. In addition to their role in maintaining bioenergetic homeostasis, changes in mitochondrial metabolism, permeability, and morphology are critical in cell fate decisions and determination. Notably, mitochondrial respiration coupled with the passage of electrons through the electron transport chain (ETC) set up a potential source of reactive oxygen species (ROS). While low to moderate increase in intracellular ROS serves as secondary messenger, an overwhelming increase as a result of either increased production and/or deficient antioxidant defenses is detrimental to biomolecules, cells, and tissues. Since ROS and mitochondria both regulate cell fate, attention has been drawn to their involvement in the various processes of carcinogenesis. To that end, the link between a prooxidant milieu and cell survival and proliferation as well as a switch to mitochondrial OXPHOS associated with recalcitrant cancers provide testimony for the remarkable metabolic plasticity as an important hallmark of cancers. In this review, the regulation of cell redox status by mitochondrial metabolism and its implications for cancer cell fate will be discussed followed by the significance of mitochondria-targeted therapies for cancer.

Organic zinc and manganese and 25-hydroxycholecalciferol improves eggshell thickness in late-phase laying hens

The aim of this study was to evaluate the effects of organic micromineral zinc (Zn) and manganese (Mn) and 25-hydroxycholecalciferol supplementation in late-phase laying hens' diets on performance, egg quality, lipid stability of fresh and stored eggs, and bone quality. The treatments were a basal diet and diets supplemented with 32 mg Zn-Met/kg diet; 26 mg Mn-Met/kg diet; 32 mg Zn-Met/kg diet and 26 mg Mn-Met/kg diet; 1500 IU 25-hydroxycholecalciferol/kg diet; 32 mg Zn-Met/kg diet; 26 mg Mn-Met/kg diet; and 1500 IU 25-hydroxycholecalciferol/kg diet. On performance, the birds supplemented with organic manganese had the lowest feed intake. Regarding egg quality, the birds supplemented with Zn-Met and Mn-Met, with 25-hydroxycholecalciferol alone, and with Zn-Met, Mn-Met and 25-hydroxycholecalciferol presented a greater eggshell thickness than those receiving the basal diet. Lipid stability of the yolk varied only according to storage time. No effect of supplementation was observed on bone quality. Supplementation with Zn-Met and Mn-Met, or associated with 25-hydroxycholecalciferol, or 25-hydroxycholecalciferol alone, improved eggshell thickness in aged white layers. However, the associated or isolated supplementation with these nutrients did not influence performance, lipid stability of fresh and stored egg yolk or bone quality.

Geometrical variations of two manganese(II) complexes with closely related quinoline-based tripodal ligands

Structural analyses of the compounds di-μ-acetato-κ4 O:O'-bis-{[2-meth-oxy-N,N-bis-(quinolin-2-ylmeth-yl)ethanamine-κ4 N,N',N'',O]manganese(II)} bis-(tetra-phen-yl-borate) di-chloro-methane 1.45-solvate, [Mn2(C23O2)2(C23H23N3O)2](C24H20B)·1.45CH2Cl2 or [Mn(DQMEA)(μ-OAc)2Mn(DQMEA)](BPh4)2·1.45CH2Cl2 or [1](BPh4)2·1.45CH2Cl2, and (acetato-κO)[2-hy-droxy-N,N-bis(quinolin-2-ylmeth-yl)ethanamine-κ4 N,N',N'',O](methanol-κO)manganese(II) tetra-phenyl-borate methanol monosolvate, [Mn(CH3COO)(C22H21N3O)(CH3OH)](C24H20B)·CH3OH or [Mn(DQEA)(OAc)(CH3OH)]BPh4·CH3OH or [2]BPh4·CH3OH, by single-crystal X-ray diffraction reveal distinct differences in the geometry of coordination of the tripodal DQEA and DQMEA ligands to MnII ions. In the asymmetric unit, compound [1](BPh4)2·(CH2Cl2)1.45 crystallizes as a dimer in which each manganese(II) center is coordinated by the central amine nitro-gen, the nitro-gen atom of each quinoline group, and the meth-oxy-oxygen of the tetra-dentate DQMEA ligand, and two bridging-acetate oxygen atoms. The symmetric MnII centers have a distorted, octa-hedral geometry in which the quinoline nitro-gen atoms are trans to each other resulting in co-planarity of the quinoline rings. For each MnII center, a coordinated acetate oxygen participates in C-H⋯O hydrogen-bonding inter-actions with the two quinolyl moieties, further stabilizing the trans structure. Within the crystal, weak π-π stacking inter-actions and inter-molecular cation-anion inter-actions stabilize the crystal packing. In the asymmetric unit, compound [2]BPh4·CH3OH crystallizes as a monomer in which the manganese(II) ion is coordinated to the central nitro-gen, the nitro-gen atom of each quinoline group, and the alcohol oxygen of the tetra-dentate DQEA ligand, an oxygen atom of OAc, and the oxygen atom of a methanol ligand. The geometry of the MnII center in [2]BPh4·CH3OH is also a distorted octa-hedron, but the quinoline nitro-gen atoms are cis to each other in this structure. Hydrogen bonding between the acetate oxygen atoms and hydroxyl (O-H⋯O) and quinolyl (C-H⋯O and N-H⋯O) moieties of the DQEA ligand stabilize the complex in this cis configuration. Within the crystal, dimerization of complexes occurs by the formation of a pair of inter-molecular O3-H3⋯O2 hydrogen bonds between the coordinated hydroxyl oxygen of the DQEA ligand of one complex and an acetate oxygen of another. Additional hydrogen-bonding and inter-molecular cation-anion inter-actions contribute to the crystal packing.

Chemotherapy-induced cognitive impairment: focus on the intersection of oxidative stress and TNFα

Chemotherapy-induced cognitive impairment (CICI) has been observed in a large fraction of cancer survivors. Although many of the chemotherapeutic drugs do not cross the blood-brain barrier, following treatment, the structure and function of the brain are altered and cognitive dysfunction occurs in a significant number of cancer survivors. The means by which CICI occurs is becoming better understood, but there still remain unsolved questions of the mechanisms involved. The hypotheses to explain CICI are numerous. More than 50% of FDA-approved cancer chemotherapy agents are associated with reactive oxygen species (ROS) that lead to oxidative stress and activate a myriad of pathways as well as inhibit pathways necessary for proper brain function. Oxidative stress triggers the activation of different proteins, one in particular is tumor necrosis factor alpha (TNFα). Following treatment with various chemotherapy agents, this pro-inflammatory cytokine binds to its receptors at the blood-brain barrier and translocates to the parenchyma via receptor-mediated endocytosis. Once in brain, TNFα initiates pathways that may eventually lead to neuronal death and ultimately cognitive impairment. TNFα activation of the c-jun N-terminal kinases (JNK) and Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathways may contribute to both memory decline and loss of higher executive functions reported in patients after chemotherapy treatment. Chemotherapy also affects the brain's antioxidant capacity, allowing for accumulation of ROS. This review expands on these topics to provide insights into the possible mechanisms by which the intersection of oxidative stress and TNFΑ are involved in chemotherapy-induced cognitive impairment.

Dynamic Oxygen Conditions Promote the Translocation of HIF-1α to the Nucleus in Mouse Blastocysts

Oxygen tension is one of the most critical factors for mammalian embryo development and its survival. The HIF protein is an essential transcription factor that activated under hypoxic conditions. In this study, we evaluated the effect of dynamic oxygen conditions on the expression of embryonic genes and translocation of hypoxia-inducible factor-1α (HIF-1α) in cultured mouse blastocysts. Two-pronuclear (2PN) zygotes harvested from ICR mice were subjected to either high oxygen (HO; 20%), low oxygen (LO; 5%), or dynamic oxygen (DO; 5% to 2%) conditions. In the DO group, PN zygotes were cultured in 5% O2 from days 1 to 3 and then in 2% O2 till day 5 after hCG injection. On day 5, the percentage of blastocysts in the cultured embryos from each group was estimated, and the embryos were also subjected to immunocytochemical and gene expression analysis. We found that the percentage of blastocysts was similar among the experimental groups; however, the percentage of hatching blastocysts in the DO and LO groups was significantly higher than that in the HO group. The total cell number of blastocysts in the DO group was significantly higher than that of both the HO and LO groups. Further, gene expression analysis revealed that the expression of genes related to the embryonic development was significantly higher in the DO group than that in the HO and LO groups. Interestingly, HIF-1α mRNA expression did not significantly differ; however, HIF-1α protein translocation from the cytoplasm to the nucleus was significantly higher in the DO group than in the HO and LO groups. Our study suggests that dynamic oxygen concentrations increase the developmental capacity in mouse preimplantation embryos through activation of the potent transcription factor HIF-1α.

In Utero Exposure to Heavy Metals and Trace Elements and Childhood Blood Pressure in a U.S. Urban, Low-Income, Minority Birth Cohort

BACKGROUND

In utero exposure to heavy metals lead (Pb), mercury (Hg), and cadmium (Cd) may be associated with higher childhood blood pressure (BP), whereas trace elements selenium (Se) and manganese (Mn) may have protective antioxidant effects that modify metal-BP associations.

OBJECTIVES

We examined the individual and joint effects of in utero exposure to Pb, Hg, Cd, Se, and Mn on childhood BP.

METHODS

We used data from the Boston Birth Cohort (enrolled 2002-2013). We measured heavy metals and trace elements in maternal red blood cells collected 24-72 h after delivery. We calculated child BP percentile per the 2017 American Academy of Pediatrics Clinical Practice Guideline. We used linear regression models to estimate the association of each metal, and Bayesian kernel machine regression (BKMR) to examine metal coexposures, with child BP between 3 to 15 years of age.

RESULTS

Our analytic sample comprised 1,194 mother-infant pairs (61% non-Hispanic Black, 20% Hispanic). Hg and Pb were not associated with child systolic BP (SBP). Se and Mn were inversely associated with child SBP percentiles, which, on average, were 6.23 points lower with a doubling of Se (95% CI: -11.51, -0.96) and 2.62 points lower with a doubling of Mn (95% CI: -5.20, -0.04). BKMR models showed similar results. Although Cd was not associated with child SBP overall, the inverse association between Mn and child SBP was stronger at higher levels of Cd (p-interaction=0.04). Consistent with this finding, in utero exposure to cigarette smoke modified the Mn-child SBP association. Among children whose mothers smoked during pregnancy, a doubling of Mn was associated with a 10.09-point reduction in SBP percentile (95% CI: -18.03, -2.15), compared with a 1.49-point reduction (95% CI: -4.21, 1.24) in children whose mothers did not smoke during pregnancy (p-interaction=0.08).

CONCLUSION

Se and Mn concentrations in maternal red blood cells collected 24-72 h after delivery were associated with lower child SBP at 3 to 15 years of age. There was an interaction between Mn and Cd on child SBP, whereby the protective association of Mn on child SBP was stronger among mothers who had higher Cd. The association of Mn and child SBP was also modified by maternal cigarette smoking-a source of Cd-during pregnancy. Optimizing in utero Se levels, as well as Mn levels in women who had high Cd or smoked during pregnancy, may protect offspring from developing high BP during childhood. https://doi.org/10.1289/EHP8325.

Lysine 53 Acetylation of Cytochrome c in Prostate Cancer: Warburg Metabolism and Evasion of Apoptosis

Prostate cancer is the second leading cause of cancer-related death in men. Two classic cancer hallmarks are a metabolic switch from oxidative phosphorylation (OxPhos) to glycolysis, known as the Warburg effect, and resistance to cell death. Cytochrome c (Cytc) is at the intersection of both pathways, as it is essential for electron transport in mitochondrial respiration and a trigger of intrinsic apoptosis when released from the mitochondria. However, its functional role in cancer has never been studied. Our data show that Cytc is acetylated on lysine 53 in both androgen hormone-resistant and -sensitive human prostate cancer xenografts. To characterize the functional effects of K53 modification in vitro, K53 was mutated to acetylmimetic glutamine (K53Q), and to arginine (K53R) and isoleucine (K53I) as controls. Cytochrome c oxidase (COX) activity analyzed with purified Cytc variants showed reduced oxygen consumption with acetylmimetic Cytc compared to the non-acetylated Cytc (WT), supporting the Warburg effect. In contrast to WT, K53Q Cytc had significantly lower caspase-3 activity, suggesting that modification of Cytc K53 helps cancer cells evade apoptosis. Cardiolipin peroxidase activity, which is another proapoptotic function of the protein, was lower in acetylmimetic Cytc. Acetylmimetic Cytc also had a higher capacity to scavenge reactive oxygen species (ROS), another pro-survival feature. We discuss our experimental results in light of structural features of K53Q Cytc, which we crystallized at a resolution of 1.31 Å, together with molecular dynamics simulations. In conclusion, we propose that K53 acetylation of Cytc affects two hallmarks of cancer by regulating respiration and apoptosis in prostate cancer xenografts.

Superoxide Dismutase Administration: A Review of Proposed Human Uses

Superoxide dismutases (SODs) are metalloenzymes that play a major role in antioxidant defense against oxidative stress in the body. SOD supplementation may therefore trigger the endogenous antioxidant machinery for the neutralization of free-radical excess and be used in a variety of pathological settings. This paper aimed to provide an extensive review of the possible uses of SODs in a range of pathological settings, as well as describe the current pitfalls and the delivery strategies that are in development to solve bioavailability issues. We carried out a PubMed query, using the keywords "SOD", "SOD mimetics", "SOD supplementation", which included papers published in the English language, between 2012 and 2020, on the potential therapeutic applications of SODs, including detoxification strategies. As highlighted in this paper, it can be argued that the generic antioxidant effects of SODs are beneficial under all tested conditions, from ocular and cardiovascular diseases to neurodegenerative disorders and metabolic diseases, including diabetes and its complications and obesity. However, it must be underlined that clinical evidence for its efficacy is limited and consequently, this efficacy is currently far from being demonstrated.

Evaluation of the compounds commonly known as superoxide dismutase and catalase mimics in cellular models

Oxidative stress that results from an imbalance between the concentrations of reactive species (RS) and antioxidant defenses is associated with many pathologies. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase are among the key enzymes that maintain the low nanomolar physiological concentrations of superoxide and hydrogen peroxide. The increase in the levels of these species and their progeny could have deleterious effects. In this context, chemists have developed SOD and CAT mimics to supplement them when cells are overwhelmed with oxidative stress. However, the beneficial activity of such molecules in cells depends not only on their intrinsic catalytic activities but also on their stability in biological context, their cell penetration and their cellular localization. We have employed cellular assays to characterize several compounds that possess SOD and CAT activities and have been frequently used in cellular and animal models. We used cellular assays that address SOD and CAT activities of the compounds. Finally, we determined the effect of compounds on the suppression of the inflammation in HT29-MD2 cells challenged by lipopolysaccharide. When the assay requires penetration inside cells, the SOD mimics Mn(III) meso-tetrakis(N-(2'-n-butoxyethyl)pyridinium-2-yl)porphyrin (MnTnBuOE-2-PyP⁵⁺) and Mn(II) dichloro[(4aR,13aR,17aR,21aR)-1,2,3,4,4a,5,6,12,13,13a,14,15,16,17,17a,18,19,20,21,21a-eicosahydro-11,7-nitrilo-7Hdibenzo[b,h] [1,4, 7,10] tetraazacycloheptadecine-κN5,κN13,κN18,κN21,κN22] (Imisopasem manganese, M40403, CG4419) were found efficacious at 10 μM, while Mn(II) chloro N-(phenolato)-N,N'-bis[2-(N-methyl-imidazolyl)methyl]-ethane-1,2-diamine (Mn1) requires an incubation at 100 μM. This study thus demonstrates that MnTnBuOE-2-PyP⁵⁺, M40403 and Mn1 were efficacious in suppressing inflammatory response in HT29-MD2 cells and such action appears to be related to their ability to enter the cells and modulate reactive oxygen species (ROS) levels.

H2O2-Driven Anticancer Activity of Mn Porphyrins and the Underlying Molecular Pathways

Mn(III) ortho-N-alkyl- and N-alkoxyalkyl porphyrins (MnPs) were initially developed as superoxide dismutase (SOD) mimics. These compounds were later shown to react with numerous reactive species (such as ONOO-, H2O2, H2S, CO3 •-, ascorbate, and GSH). Moreover, the ability of MnPs to oxidatively modify activities of numerous proteins has emerged as their major mechanism of action both in normal and in cancer cells. Among those proteins are transcription factors (NF-κB and Nrf2), mitogen-activated protein kinases, MAPKs, antiapoptotic bcl-2, and endogenous antioxidative defenses. The lead Mn porphyrins, namely, MnTE-2-PyP5+ (BMX-010, AEOL10113), MnTnBuOE-2-PyP5+ (BMX-001), and MnTnHex-2-PyP5+, were tested in numerous injuries of normal tissue and cellular and animal cancer models. The wealth of the data led to the progression of MnTnBuOE-2-PyP5+ into four Phase II clinical trials on glioma, head and neck cancer, anal cancer, and multiple brain metastases, while MnTE-2-PyP5+ is in Phase II clinical trial on atopic dermatitis and itch.

Superoxide produced by mitochondrial site IQ inactivates cardiac succinate dehydrogenase and induces hepatic steatosis in Sod2 knockout mice

Superoxide produced by mitochondria has been implicated in numerous physiologies and pathologies. Eleven different mitochondrial sites that can produce superoxide and/or hydrogen peroxide (O₂^.-/H₂O₂) have been identified in vitro, but little is known about their contributions in vivo. We introduce novel variants of S1QELs and S3QELs (small molecules that suppress O₂^.-/H₂O₂ production specifically from mitochondrial sites I_Q and III_Qo, respectively, without compromising bioenergetics), that are suitable for use in vivo. When administered by intraperitoneal injection, they achieve total tissue concentrations exceeding those that are effective in vitro. We use them to study the engagement of sites I_Q and III_Qo in mice lacking functional manganese-superoxide dismutase (SOD2). Lack of SOD2 is expected to elevate superoxide levels in the mitochondrial matrix, and leads to severe pathologies and death about 8 days after birth. Compared to littermate wild-type mice, 6-day-old Sod2^-/- mice had significantly lower body weight, lower heart succinate dehydrogenase activity, and greater hepatic lipid accumulation. These pathologies were ameliorated by treatment with a SOD/catalase mimetic, EUK189, confirming previous observations. A 3-day treatment with S1QEL352 decreased the inactivation of cardiac succinate dehydrogenase and hepatic steatosis in Sod2^-/- mice. S1QEL712, which has a distinct chemical structure, also decreased hepatic steatosis, confirming that O₂^.- derived specifically from mitochondrial site I_Q is a significant driver of hepatic steatosis in Sod2^-/- mice. These findings also demonstrate the ability of these new S1QELs to suppress O₂^.- production in the mitochondrial matrix in vivo. In contrast, suppressing site III_Qo using S3QEL941 did not protect, suggesting that site III_Qo does not contribute significantly to mitochondrial O₂^.- production in the hearts or livers of Sod2^-/- mice. We conclude that the novel S1QELs are effective in vivo, and that site I_Q runs in vivo and is a significant driver of pathology in Sod2^-/- mice.

Fine particulate matter (PM2.5) promotes IgE-mediated mast cell activation through ROS/Gadd45b/JNK axis

BACKGROUND

Mast cells play an important role in allergic responses and persistently exposure to environmental fine particulate matter (PM2.5) exacerbates allergic diseases,but the details remained elucidative.

OBJECTIVES

To investigate the effect of PM2.5 on IgE-mediated mast cell responses through an IgE-mediated mouse model and mast cell activation.

METHODS

The β-hexosaminidase release and a BALB/c model of passive cutaneous anaphylaxis (PCA) was used to test IgE-mediated mast cells activation in vitro and in vivo. RNA-Seq technique was conducted to study the gene expression profile. Reactive oxygen species (ROS) production was measured by flow-cytometry. RT-PCR,WB and ELISA were performed to examine targeting molecules expression.

RESULTS

PM2.5 facilitated IgE-mediated degranulation and increased cytokines expression in mast cells. Meanwhile, the Evan's blue extravasation as well as serum cytokines in mice was increased after treatment with PM2.5. Furthermore, PM2.5 treatment dramatically increased the expression of Gadd45b which is an oxidative stress molecule that directly activates down-stream pathway, such as MEKK4/JNK. PM2.5 treatment activated MEKK4, JNK1/2 but not ERK1/2 and p38. Meanwhile, Knockdown of Gadd45b significantly attenuated PM2.5-mediated JNK1/2 activation and expression of cytokines. In addition, a JNK1/2-specific inhibitor SP600125 blocked IgE-mediated mast cell activation and cytokine release in PCA model mice. Moreover, PM2.5 treatment increased the ROS level and ROS inhibitor dramatically blocked the PM2.5-induced ROS production and reversed the PM2.5-mediated gene expression in the mitochondrial respiratory chain.

CONCLUSIONS

PM2.5 regulates ROS production through Gadd45b/MEKK4/JNK pathway, facilitating IgE-mediated mast cell activation.

Manganese(II)-Based Responsive Contrast Agent Detects Glucose-Stimulated Zinc Secretion from the Mouse Pancreas and Prostate by MRI

A Mn(II)-based zinc-sensitive MRI contrast agent, MnPyC3A-BPEN, was prepared, characterized, and applied in imaging experiments to detect glucose-stimulated zinc secretion (GSZS) from the mouse pancreas and prostate in vivo. Thermodynamic and kinetic stability tests showed that MnPyC3A-BPEN has superior kinetic inertness compared to GdDTPA, is less susceptible to transmetalation in the presence of excess Zn2+ ions, and less susceptible to transchelation by albumin. In comparison with other gadolinium-based zinc sensors bearing a single zinc binding moiety, MnPyC3A-BPEN appears to be a reliable alternative for imaging β-cell function in the pancreas and glucose-stimulated zinc secretion from the prostate.

Superoxide Dismutase Multigene Family from a Primitive Chondrostean Sturgeon, Acipenser baerii: Molecular Characterization, Evolution, and Antioxidant Defense during Development and Pathogen Infection

Three distinct superoxide dismutases (SODs)-copper/zinc-SOD (SOD1), manganese-SOD (SOD2), and extracellular copper/zinc-SOD (SOD3)-were identified from a primitive chondrostean fish, Acipenser baerii, enabling the comparison of their transcriptional regulation patterns during development, prelarval ontogeny, and immune stimulation. Each A. baerii SOD isoform (AbSOD) shared conserved structural features with its vertebrate orthologs; however, phylogenetic analyses hypothesized a different evolutionary history for AbSOD3 relative to AbSOD1 and AbSOD2 in the vertebrate lineage. The AbSOD isoforms showed different tissue distribution patterns; AbSOD1 was predominantly expressed in most tissues. The expression of the AbSOD isoforms showed isoform-dependent dynamic modulation according to embryonic development and prelarval ontogenic behaviors. Prelarval microinjections revealed that lipopolysaccharide only induced AbSOD3 expression, while Aeromonas hydrophila induced the expression of AbSOD2 and AbSOD3. In fingerlings, the transcriptional response of each AbSOD isoform to bacterial infection was highly tissue-specific, and the three isoforms exhibited different response patterns within a given tissue type; AbSOD3 was induced the most sensitively, and its induction was the most pronounced in the kidneys and skin. Collectively, these findings suggest isoform-dependent roles for the multigene SOD family in antioxidant defenses against the oxidative stress associated with development and immune responses in these endangered sturgeon fish.

Val16A SOD2 Polymorphism Promotes Epithelial-Mesenchymal Transition Antagonized by Muscadine Grape Skin Extract in Prostate Cancer Cells

Epithelial–mesenchymal transition (EMT), a key event in cancer metastasis, allows polarized epithelial cells to assume mesenchymal morphologies, enhancing invasiveness and migration, and can be induced by reactive oxygen species (ROS). Val16A (Ala) SOD2 polymorphism has been associated with increased prostate cancer (PCa) risk. We hypothesized that SOD2 Ala single nucleotide polymorphism (SNP) may promote EMT. We analyzed SOD2 expression and genotype in various prostate cell lines. Stable overexpression of Ala-SOD2 or Val-SOD2 allele was performed in Lymph Node Carcinoma of the Prostate (LNCaP) cells followed by analysis of intracellular ROS and EMT marker protein expression. Treatments were performed with muscadine grape skin extract (MSKE) antioxidant, with or without addition of H₂O₂ to provide further oxidative stress. Furthermore, MTS cell proliferation, cell migration, and apoptosis assays were completed. The results showed that SOD2 expression did not correlate with tumor aggressiveness nor SOD2 genotype. We demonstrated that the Ala-SOD2 allele was associated with marked induction of EMT indicated by higher Snail and vimentin, lower E-cadherin, and increased cell migration, when compared to Val-SOD2 allele or Neo control cells. Ala-SOD2 SNP cells exhibited increased levels of total ROS and superoxide and were more sensitive to co-treatment with H₂O₂ and MSKE, which led to reduced cell growth and increased apoptosis. Additionally, MSKE inhibited Ala-SOD2 SNP-mediated EMT. Our data indicates that treatment with a combination of H₂O₂-generative drugs, such as certain chemotherapeutics and antioxidants such as MSKE that targets superoxide, hold promising therapeutic potential to halt PCa progression in the future.

Electronic investigation of the effect of substituents on the SOD mimic activity of copper (II) complexes with 8-hydroxyquinoline-derived ligands

Density functional theory (DFT) calculations were used to study the superoxide dismutase (SOD) mimic activity of two Cu²⁺ complexes with ligands derived from 8-hydroxyquinoline (8-HQ). Electron-donating and -withdrawing substituent groups were inserted into the structures to verify changes in the reactivity. The theoretical parameters obtained were compared and validated with the experimental data available. The results showed that the reduction process occurs with greater participation of the 8-HQ ligand and the oxidation step occurs with participation of the copper atom in the complexes, where the electron received during the reduction step is used to reduce the Cu²⁺ to Cu⁺. The calculated electronic affinity showed good correlation with the experimental mimetic activity, and the analysis of this property, of total charge and of molecular orbitals indicated an increase in the mimetic activity with the insertion of electron-withdrawing substituent groups in the structures.

Catalytic Antioxidants in the Kidney

Reactive oxygen species and reactive nitrogen species are highly implicated in kidney injuries that include acute kidney injury, chronic kidney disease, hypertensive nephropathy, and diabetic nephropathy. Therefore, antioxidant agents are promising therapeutic strategies for kidney diseases. Catalytic antioxidants are defined as small molecular mimics of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, and some of them function as potent detoxifiers of lipid peroxides and peroxynitrite. Several catalytic antioxidants have been demonstrated to be effective in a variety of in vitro and in vivo disease models that are associated with oxidative stress, including kidney diseases. This review summarizes the evidence for the role of antioxidant enzymes in kidney diseases, the classifications of catalytic antioxidants, and their current applications to kidney diseases.

SOD2 deficiency-induced oxidative stress attenuates steroidogenesis in mouse ovarian granulosa cells

This study investigated the effects of SOD2 (MnSOD)-deficiency-induced excessive oxidative stress on ovarian steroidogenesis in vivo and isolated and cultured granulosa cells using WT and Sod2+/- mice. Basal and 48 h eCG-stimulated plasma progesterone levels were decreased ~50% in female Sod2+/- mice, whereas plasma progesterone levels were decreased ~70% in Sod2+/- mice after sequential stimulation with eCG followed by hCG. Sod2+/- deficiency caused about 50% reduction in SOD2 activity in granulosa cells. SOD2-deficiency also caused a marked reduction in progestins and estradiol in isolated granulosa cells. qRT-PCR measurements indicated that the mRNA expression levels of StAR protein and steroidogenic enzymes are decreased in the ovaries of Sod2+/- mice. Further studies showed a defect in the movement of mobilized cytosolic cholesterol to mitochondria. The ovarian membrane from Sod2+/- mice showed higher susceptibility to lipid peroxidation. These data indicates that SOD2-deficiency induced oxidative stress inhibits ovarian granulosa cell steroidogenesis primarily by interfering with cholesterol transport to mitochondria and attenuating the expression of Star protein gene and key steroidogenic enzyme genes.

Bovine serum albumin interactive one dimensional hexanuclear manganese(iii) complex: synthesis, structure, binding and molecular docking studies

A hexanuclear Mn(III) complex was synthesized and structiurally characterized which exhibits fluorescence quenching of BSA probably through site selective binding at the mouth of site I in subdomain IIA.

Visible light-mediated applications of methylene blue in organic synthesis

This review presents the manipulation of methylene blue in visible-light-assisted organic synthesis.

Comparative Genomic and Physiological Analyses of a Superoxide Dismutase Mimetic (SODm-123) for Its Ability to Respond to Oxidative Stress in Tomato Plants

Superoxide dismutases (SODs) are a group of enzymes that have a crucial role in controlling oxidative stress in plants. Here, we synthesized an environmentally friendly SOD mimic, SODm-123, from L-aspartic acid and manganese oxide. SODm-123 showed similar enzymatic activity to Mn-SOD. To gain insights into the role of SODm-123 in oxidative stress tolerance, a series of experiments were conducted to assess the physiological and molecular responses of tomato plants when treated with SODm-123. The results showed that the levels of O₂^-• and H₂O₂ in tomato cells were affected by SODm-123 treatment, indicating that SODm-123 can control oxidative stress like Mn-SOD. The results also exhibited that SODm-123 increased the contents of photosynthetic pigments. However, it was noted that SODm-123 resulted in a reduction in the content of soluble sugar and MDA. These results indicate that SODm-123 promoted the efficiency of photosynthesis by regulating the content of H₂O₂. To further investigate the role of SODm-123 in controlling oxidative stress, a transcriptome analysis was used to identify differentially expressed genes (DEGs) associated with SODm-123 treatment. The results indicated that SODm-123 treatment resulted in 341 differentially expressed genes (DEGs) in treated tomato leaves at 96 h after treatment. Kyoto encyclopedia of genes and genomes (KEGG) revealed that DEGs were involved in pathways such as photosynthetic pigment biosynthesis, ABC transporters, sugar metabolism, and MAPK signaling, which further confirmed a positive role of SODm-123 in improving stress tolerance in plants. Overall, the results of this study suggest that SODm-123 promotes the growth and development of tomato seedlings and therefore can be used as a potential growth-promoting agent for plants.

Reduction of peroxynitrite by some manganoporphyrins of AEOL series: DFT approach with dispersion correction and NBO analysis

The AEOL series of manganoporphyrins (MnP; AEOL compounds were named by US Aeolus pharmaceuticals) designed as superoxide dismutase mimic are well-known for their powerful catalytic activity to neutralize reactive oxygen and nitrogen species. Reductive oxygen atom cleavage from peroxynitrite (ONOO^-) to form NO₂ in aqueous solution by some AEOL compounds (AEOL-10113, AEOL-10150, AEOL-11114 and AEOL-11203) was studied by DFT/M06-2X computations with D3 dispersion correction and gCP (geometrical counterpoise correction) for basis set superposition error. DFT computation showed that AEOL-10150 can form the most stable association complex {MnP^…OONO} among four AEOL models. AEOL-10150 complex with ONOO^- has the lowest deformation energy. In AEOL compounds and their association complexes with ONOO^-, Mn atom prefered the high spin state (S = 2) to the intermediate spin state (S = 1). Natural bond orbital analysis showed that electron transfer from the most negative oxygen atom in ONOO^- to Mn atom in MnP has the biggest interaction energy among all kinds of donor-acceptor interactions between ONOO^- and MnP.

Methylation-dependent antioxidant-redox imbalance regulates hypertensive kidney injury in aging

The prevalence of hypertension increases with age, and oxidative stress is a major contributing factor to the pathogenesis of hypertension-induced kidney damage in aging. The nicotinamide adenine dinucleotide phosphate (NADPH) family is one of the major sources of reactive oxygen species (ROS) generation, and several NADPH oxidase isoforms are highly expressed in the kidney. Although epigenetic protein modification plays a role in organ injury, the methylation of the oxidant-antioxidant defense system and their role in hypertension-induced kidney damage in aging remains underexplored. The present study investigated the role of NADPH oxidase 4, superoxide dismutases (SODs), catalase, and NOS in Ang-II induced kidney damage in aging. Wild type (WT, C57BL/6J) mice aged 12-14 and 75-78 weeks were used and treated with or without Ang-II (1000 ng/kg/min) for 4 weeks with control mice receiving saline. Aged mice with or without Ang-II exhibited higher mean BP, lower renal blood flow, and decreased renal vascular density compared to young mice. While superoxide, 4-HNE, p22^phox, Nox4, iNOS were increased in the aged kidney, the expression of eNOS, MnSOD, CuSOD, catalase, Sirt1, and -3 as well as the ratio of GSH/GSSG, and activities of SODs and catalase were decreased compared to young control mice. The changes further deteriorated with Ang-II treatment. In Ang-II treated aged mice, the expressions of DNMTs were increased and associated with increased methylation of SODs, Sirt1, and Nox4. We conclude that hypermethylation of antioxidant enzymes in the aged kidney during hypertension worsens redox imbalance leading to kidney damage.

Mediation of oxidative stress toxicity induced by pyrethroid pesticides in fish

Organophosphate and organochlorine pesticides are banned in most countries because they cause high toxicity and bioaccumulation in non-target organisms. Pyrethroid pesticides have been applied to agriculture and aquaculture since the 1970s to replace traditional pesticides. However, pyrethroids are approximately 1000 times more toxic to fish than to mammals and birds. Fish-specific organs such as the gills and their late metabolic action against this type of pesticide make fish highly susceptible to the toxicity of pyrethroid pesticides. Oxidative stress plays an important role in the neurological, reproductive, and developmental toxicity caused by pyrethroids. Deltamethrin, cypermethrin, and lambda-cyhalothrin are representative pyrethroid pesticides that induce oxidative stress in tissues such as the gills, liver, and muscles of fish and cause histopathological changes. Although they are observed in low concentrations in aquatic environments such as rivers, lakes, and surface water they induce DNA damage and apoptosis in fish. Pyrethroid pesticides cause ROS-mediated oxidative stress in fish species including carp, tilapia, and trout. They also cause lipid peroxidation and alter the state of DNA, proteins, and lipids in the cells of fish. Moreover, changes in antioxidant enzyme activity following pyrethroid pesticide exposure make fish more susceptible to oxidative stress caused by environmental pollutants. In this review, we examine the occurrence of pyrethroid pesticides in the aquatic environment and oxidative stress-induced toxicity in fish exposed to pyrethroids.

Manganese Superoxide Dismutase Dysfunction and the Pathogenesis of Kidney Disease

The mitochondria are a major source of reactive oxygen species (ROS). Superoxide anion (O₂^•–) is produced by the process of oxidative phosphorylation associated with glucose, amino acid, and fatty acid metabolism, resulting in the production of adenosine triphosphate (ATP) in the mitochondria. Excess production of reactive oxidants in the mitochondria, including O₂^•–, and its by-product, peroxynitrite (ONOO^–), which is generated by a reaction between O₂^•– with nitric oxide (NO^•), alters cellular function via oxidative modification of proteins, lipids, and nucleic acids. Mitochondria maintain an antioxidant enzyme system that eliminates excess ROS; manganese superoxide dismutase (Mn-SOD) is one of the major components of this system, as it catalyzes the first step involved in scavenging ROS. Reduced expression and/or the activity of Mn-SOD results in diminished mitochondrial antioxidant capacity; this can impair the overall health of the cell by altering mitochondrial function and may lead to the development and progression of kidney disease. Targeted therapeutic agents may protect mitochondrial proteins, including Mn-SOD against oxidative stress-induced dysfunction, and this may consequently lead to the protection of renal function. Here, we describe the biological function and regulation of Mn-SOD and review the significance of mitochondrial oxidative stress concerning the pathogenesis of kidney diseases, including chronic kidney disease (CKD) and acute kidney injury (AKI), with a focus on Mn-SOD dysfunction.

Manipulating Sirtuin 3 pathway ameliorates renal damage in experimental diabetes

More effective treatments for diabetic nephropathy remain a major unmet clinical need. Increased oxidative stress is one of the most important pathological mechanisms that lead to kidney damage and functional impairment induced by diabetes. Sirtuin 3 (SIRT3) is the main mitochondrial deacetylase and critically regulates cellular reactive oxygen species (ROS) production and detoxification. Honokiol is a natural biphenolic compound that, by activating mitochondrial SIRT3, can carry out anti-oxidant, anti-inflammatory and anti-fibrotic activities. Here, we sought to investigate the renoprotective effects of honokiol in BTBR ob/ob mice with type 2 diabetes. Diabetic mice were treated with vehicle or honokiol between the ages of 8 and 14 weeks. Wild-type mice served as controls. Renal Sirt3 expression was significantly reduced in BTBR ob/ob mice, and this was associated with a reduction in its activity and increased ROS levels. Selective activation of SIRT3 through honokiol administration translated into the attenuation of albuminuria, amelioration of glomerular damage, and a reduction in podocyte injury. SIRT3 activation preserved mitochondrial wellness through the activation of SOD2 and the restoration of PGC-1α expression in glomerular cells. Additionally, the protective role of SIRT3 in glomerular changes was associated with enhanced tubular Sirt3 expression and upregulated renal Nampt levels, indicating a possible tubule-glomerulus retrograde interplay, which resulted in improved glomerular SIRT3 activity. Our results demonstrate the hitherto unknown renoprotective effect of SIRT3 against diabetic glomerular disease and suggest that the pharmacological modulation of SIRT3 activity is a possible novel approach to treating diabetic nephropathy.

Manganese porphyrin, MnTE-2-PyP, treatment protects the prostate from radiation-induced fibrosis (RIF) by activating the NRF2 signaling pathway and enhancing SOD2 and sirtuin activity

Radiation therapy is a frequently used treatment for prostate cancer patients. Manganese (III) meso-tetrakis (N-ethylpyridinium-2-yl) porphyrin (MnTE-2-PyP or T2E or BMX-010) and other similar manganese porphyrin compounds that scavenge superoxide molecules have been demonstrated to be effective radioprotectors and prevent the development of radiation-induced fibrosis (RIF). However, understanding the molecular pathway changes associated with these compounds remains limited for radioprotection. Recent RNA-sequencing data from our laboratory revealed that MnTE-2-PyP treatment activated the nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway. Therefore, we hypothesize that MnTE-2-PyP protects the prostate from RIF by activating the NRF2 signaling pathway. We identified that MnTE-2-PyP is a post-translational activator of NRF2 signaling in prostate fibroblast cells, which plays a major role in fibroblast activation and myofibroblast differentiation. The mechanism of NRF2 activation involves an increase in hydrogen peroxide and a corresponding decrease in kelch-like ECH-associated protein 1 (KEAP1) levels. Activation of NRF2 signaling leads to an increase in expression of NAD(P)H dehydrogenase [quinone] 1 (NQO1), nicotinamide adenine dinucleotide (NAD+) levels, sirtuin activity (nuclear and mitochondrial), and superoxide dismutase 2 (SOD2) expression/activity. Increase in mitochondrial sirtuin activity correlates with a decrease in SOD2 (K122) acetylation. This decrease in SOD2 K122 acetylation correlates with an increase in SOD2 activity and mitochondrial superoxide scavenging capacity. Further, in human primary prostate fibroblast cells, the NRF2 pathway plays a major role in the fibroblast to myofibroblast transformation, which is responsible for the fibrotic phenotype. In the context of radiation protection, MnTE-2-PyP fails to prevent fibroblast to myofibroblast transformation in the absence of NRF2 signaling. Collectively, our results indicate that the activation of the NRF2 signaling pathway by MnTE-2-PyP is at least a partial mechanism of radioprotection in prostate fibroblast cells.

Role of Divalent Cations in HIV-1 Replication and Pathogenicity

Divalent cations are essential for life and are fundamentally important coordinators of cellular metabolism, cell growth, host-pathogen interactions, and cell death. Specifically, for human immunodeficiency virus type-1 (HIV-1), divalent cations are required for interactions between viral and host factors that govern HIV-1 replication and pathogenicity. Homeostatic regulation of divalent cations' levels and actions appear to change as HIV-1 infection progresses and as changes occur between HIV-1 and the host. In people living with HIV-1, dietary supplementation with divalent cations may increase HIV-1 replication, whereas cation chelation may suppress HIV-1 replication and decrease disease progression. Here, we review literature on the roles of zinc (Zn2+), iron (Fe2+), manganese (Mn2+), magnesium (Mg2+), selenium (Se2+), and copper (Cu2+) in HIV-1 replication and pathogenicity, as well as evidence that divalent cation levels and actions may be targeted therapeutically in people living with HIV-1.

Piscidin-1 Induces Apoptosis via Mitochondrial Reactive Oxygen Species-Regulated Mitochondrial Dysfunction in Human Osteosarcoma Cells

Osteosarcoma (OSA) is the most common type of cancer that originates in the bone and usually occurs in young children. OSA patients were treated with neoadjuvant chemotherapy and surgery, and the results were disappointing. Marine antimicrobial peptides (AMPs) have been the focus of antibiotic research because they are resistant to pathogen infection. Piscidin-1 is an AMP from the hybrid striped bass (Morone saxatilis × M. chrysops) and has approximately 22 amino acids. Research has shown that piscidin-1 can inhibit bacterial infections and has antinociception and anti-cancer properties; however, the regulatory effects of piscidin-1 on mitochondrial dysfunction in cancer cells are still unknown. We aimed to identify the effects of piscidin-1 on mitochondrial reactive oxygen species (mtROS) and apoptosis in OSA cells. Our analyses indicated that piscidin-1 has more cytotoxic effects against OSA cells than against lung and ovarian cancer cells; however, it has no effect on non-cancer cells. Piscidin-1 induces apoptosis in OSA cells, regulates mtROS, reduces mitochondrial antioxidant manganese superoxide dismutase and mitochondrial transmembrane potential, and decreases adenosine 5′-triphosphate production, thus leading to mitochondrial dysfunction and apoptosis. The mitochondrial antioxidant, mitoTempo, reduces the apoptosis induced by piscidin-1. Results suggest that piscidin-1 has potential for use in OSA treatment.

Antioxidant Nanotherapies for the Treatment of Inflammatory Diseases

Reactive oxygen species (ROS) are essential in regulating various physiological functions. However, overproduction of ROS is implicated in the pathogenesis of various inflammatory diseases. Antioxidant therapy has thus represented an effective strategy for the treatment of oxidative stress relevant inflammatory diseases. Conventional anti-oxidative agents showed limited in vivo effects owing to their non-specific distribution and low retention in disease sites. Over the past decades, significant achievements have been made in the development of antioxidant nanotherapies that exhibit multiple advantages such as excellent pharmacokinetics, stable anti-oxidative activity, and intrinsic ROS-scavenging properties. This review provides a comprehensive overview on recent advances in antioxidant nanotherapies, including ROS-scavenging inorganic nanoparticles, organic nanoparticles with intrinsic antioxidant activity, and drug-loaded anti-oxidant nanoparticles. We highlight the biomedical applications of antioxidant nanotherapies in the treatment of different inflammatory diseases, with an emphasis on inflammatory bowel disease, cardiovascular disease, and brain diseases. Current challenges and future perspectives to promote clinical translation of antioxidant nanotherapies are also briefly discussed.

Mitochondrial reactive oxygen species: the effects of mitochondrial ascorbic acid vs untargeted and mitochondria-targeted antioxidants

PREMISE

Mitochondria represent critical sites for reactive oxygen species (ROS) production, which dependent on concentration is responsible for the regulation of both physiological and pathological processes.

PURPOSE

Antioxidants in mitochondria regulate the redox balance, prevent mitochondrial damage and dysfunction and maintain a physiological ROS-dependent signaling. The aim of the present review is to provide critical elements for addressing this issue in the context of various pharmacological approaches using antioxidants targeted or non-targeted to mitochondria. Furthermore, this review focuses on the mitochondrial antioxidant effects of ascorbic acid (AA), providing clues on the complexities associated with the cellular uptake and subcellular distribution of the vitamin.

CONCLUSIONS

Antioxidants that are not specifically targeted to mitochondria fail to accumulate in significant amounts in critical sites of mitochondrial ROS production and may eventually interfere with the ensuing physiological signaling. Mitochondria-targeted antioxidants are more effective, but are expected to interfere with the mitochondrial ROS-dependent physiologic signaling. AA promotes multiple beneficial effects in mitochondria. The complex regulation of vitamin C uptake in these organelles likely contributes to its versatile antioxidant response, thereby providing a central role to the vitamin for adequate control of mitochondrial dysfunction associated with increased mitochondrial ROS production.

Effect of soil microbial feeding on gut microbiome and cadmium toxicity in Caenorhabditis elegans

Microbial community of an organism plays an important role on its fitness, including stress responses. In this study, we investigated the effect of the culturable subset of soil microbial community (SMB) on the stress response of the soil nematode Caenorhabditis elegans, upon exposure to one of the major soil contaminants, cadmium (Cd). Life history traits and the stress responses to Cd exposure were compared between SMB- and Escherichia coli strain OP50-fed worms. SMB-fed worms showed higher reproduction rates and longer lifespans. Also, the SMB-fed worms showed more tolerant response to Cd exposure. Gene expression profiling suggested that the chemical stress and immune response of worms were boosted upon SMB feeding. Finally, we investigated C. elegans gut microbial communities in the presence and absence of Cd in OP50- and SMB-fed C. elegans. In the OP50-fed worms, changes in microbial community by Cd exposure was severe, whereas in the SMB-fed worms, it was comparatively weak. Our results suggest that the SMB affects the response of C. elegans to Cd exposure and highlight the importance of the gut microbiome in host stress response.

Classification of Metal-based Drugs According to Their Mechanisms of Action

Metal-based drugs and imaging agents are extensively used in the clinic for the treatment and diagnosis of cancers and a wide range of other diseases. The current clinical arsenal of compounds operate via a limited number of mechanisms, whereas new putative compounds explore alternative mechanisms of action, which could potentially bring new chemotherapeutic approaches into the clinic. In this review, metal-based drugs and imaging agents are characterized according to their primary mode of action and the key properties and features of each class of compounds are defined, wherever possible. A better understanding of the roles played by metal compounds at a mechanistic level will help to deliver new metal-based therapies to the clinic, by providing an alternative, targeted and rational approach, to supplement non-targeted screening of novel chemical entities for biological activity.

Anti-inflammatory activity of superoxide dismutase mimics functionalized with cell-penetrating peptides

A superoxide dismutase mimic was functionalized with three peptides: -R9, -RRWWRRWRR or -F_x-r-F_x-K (MPP). They were studied in intestinal epithelial cells in an inorganic cellular chemistry approach: quantification, distribution and bio-activity.

The Crystal Structure of the Manganese Superoxide Dismutase from Geobacillus stearothermophilus: Parker and Blake (1988) Revisited

Superoxide dismutase (SOD) is an almost ubiquitous metalloenzyme in aerobic organisms that catalyses the disproportionation of superoxide. Geobacillus stearothermophilus MnSOD is the only published MnSOD structure that does not have its coordinates publicly available, yet it is one of the more cited structures in the SOD literature. The structure has now been refined with modern programs, yielding a significantly improved structure which has been deposited in the Protein Data Bank. Importantly, the further refined structure reveals the presence of a catalytically important fifth ligand, water, to the metal centre, as observed in other SOD structures.

Intracellular location matters: rationalization of the anti-inflammatory activity of a manganese(ii) superoxide dismutase mimic complex

The study of Mn-based superoxide dismutase mimic conjugated with a multimodal Re-probe in a cellular model of oxidative stress revealed that its bioactivity is associated with its accumulation at the mitochondria.

An easy-to-implement combinatorial approach involving an activity-based assay for the discovery of a peptidyl copper complex mimicking superoxide dismutase

A strategy combining combinatorial chemistry and an activity-based screening leads to the development of a peptidyl catalytic drug that reduces the oxidative stress in cellular models.