Superoxide Species Research Articles

Selenomethionine and Methioninase: Selenium Free Radical Anticancer Activity.

Colloidal selenium, was first used to treat cancer as early as 1911 in both humans and mice. Selenium was identified as the toxic component in forage plants of sheep, cattle, and horses in the 1930s. The animal toxicity of selenium compounds was determined to be from the metabolism by animals of the elevated concentrations of Se-methylselenocysteine and selenomethionine in plants. The metabolism of both Se-methylselenocysteine and selenomethionine by animals gives rise to the metabolite, methylselenide (CH3Se-), which if in sufficient concentration oxidizes thiols and generates superoxide and other reactive oxygen species. Cancer cells that may overly express methionine gamma-lyase, or beta-lyase (methioninase), by induced viral genomic expression, are susceptible to free radical-induced apoptosis from selenomethionine or Se-methylselenocysteine supplementation.

Hydrogen atom abstraction by synthetic heme ferric superoxide and hydroperoxide species.

To date, artificial dioxygen adducts of heme have not been demonstrated to be able to oxidize organic substrates in sharp contrast to their non-heme analogues and naturally occurring enzymes like heme dioxygenases. To address this apparent anomaly, an iron porphyrin complex is synthesized which includes a pendant quinol group. The corresponding dioxygen bound iron porphyrin species is demonstrated to perform hydrogen atom transfer (HAT) from the quinol group appended to the porphyrin ligand. The resultant ferric peroxide, formed by the first HAT, performs a 2nd HAT generating a ferryl species (FeIV[double bond, length as m-dash]O) and resulting in the 2e-/2H+ oxidation of the pendant hydroquinone to quinone.

The Molecular Regulation and Functional Roles of NOX5.

NOX (NADPH oxidases) are a family of NADPH-dependent transmembrane enzymes that synthesize superoxide and other reactive oxygen species. There are seven isoforms (NOX1-5 and DUOX1-2) which derive from a common ancestral NOX. NOX enzymes are distinguished by different modes of activation, the types of ROS that are produced, the cell types where they are expressed, and distinct functional roles. NOX5 was one of the earliest eukaryotic Nox enzymes to evolve and ironically the last isoform to be discovered in humans. In the time since its discovery, our knowledge of the regulation of NOX5 has expanded tremendously, and we now have a more comprehensive understanding of the molecular mechanisms underlying NOX5-dependent ROS production. In contrast, the cell types where NOX5 is robustly expressed and its functional significance in health and disease remain an underdeveloped area. The goal of this chapter is to provide an up-to-date overview of the mechanisms regulating NOX5 function and its importance in human physiology and pathophysiology.

Infrared photodissociation spectroscopy of di-manganese oxide cluster cations.

Infrared multiple-photon dissociation (IR-MPD) spectroscopy and density functional theory (DFT) calculations have been employed to elucidate the geometric structure of a series of di-manganese oxide clusters Mn2Ox+ (x = 4-7). The theoretical exploration predicts that all investigated clusters contain a rhombus-like Mn2O2 core with up to four, terminally bound, oxygen atoms. The short Mn-O bond length of the terminal oxygen atoms of ≤1.58 Å indicates triple bond character instead of oxyl radical formation. However, the IR-MPD spectra reveal that higher energy isomers with up to two O2 molecules η2-coordinated to the cluster core can be kinetically trapped under the given experimental conditions. In these complexes, all O2 units are activated to superoxide species. In addition, the sequential increase of the oxygen content in the cluster allows for a controlled increase of the positive charge localized on the Mn atoms reaching a maximum for Mn2O7+.

Effect of Arsenic Toxicity on Photosynthesis, Oxidative Stress and Alleviation of Toxicitywith Herbal Extracts in Growing Rice Seedlings

When seedlings of an Indica rice cultivar Malaviya-36 were raised for 8 days in hydroponics in Yoshida nutrient solution containing 25 iM NaAsO2, it was observed that arsenic treatment to the seedlings caused decline in plant height, fresh weight, relative water content, net photosynthetic rate, stomatal conductance, intracellular CO2 concentration and transpiration rate. The decline was greater with increase in the duration of As treatment. Arsenic treated seedlings showed elevated levels of the reactive oxygen species superoxide radicals, H2O2 and increased oxidative stress in the tissues. When aqueous extracts prepared from leaves of the two plants, Neem (Azadirachta indica) and Tulsi (Ocimum sanctum) were added in As containing growth medium, a marked alleviation of As toxicity was observed in relation to growth parameters, photosynthetic activities and extent of oxidative stress in the tissues. Results suggest that both A. indica and O. sanctum aqueous extracts have potential to alleviate arsenic toxicity in rice seedlings with A. indica extract showing greater efficacy than O. sanctum.

Surface Passivation of Perovskite Films via Iodide Salt Coatings for Enhanced Stability of Organic Lead Halide Perovskite Solar Cells

Organic–inorganic halide perovskite materials have emerged as attractive alternatives to conventional solar cells, but device stability remains a concern. Recent research has demonstrated that the formation of superoxide species under exposure of the perovskite to light and oxygen leads to the degradation of CH3NH3PbI3 perovskites. In particular, it has been revealed that iodide vacancies in the perovskite are key sites in facilitating superoxide formation from oxygen. This paper shows that passivation of CH3NH3PbI3 films with an iodide salt, namely phenylethylammonium iodide (PhEtNH3I) can significantly enhance film and device stability under light and oxygen stress, without compromising power conversion efficiency. These observations are consistent with the iodide salt treatment reducing iodide vacancies and therefore lowers the yield of superoxide formation and improves stability. The present study elucidates a pathway to the future design and optimization of perovskite solar cells with greater stability.

Atomic-Scale Explanation of O2 Activation at the Au-TiO2 Interface.

By a combination of electron paramagnetic resonance spectroscopy, finite-temperature ab initio simulations, and electronic structure analyses, the activation of molecular dioxygen at the interface of gold nanoparticles and titania in Au/TiO2 catalysts is explained at the atomic scale by tracing processes down to the molecular orbital picture. Direct evidence is provided that excess electrons in TiO2, for example created by photoexcitation of the semiconductor, migrate to the gold particles and from there to oxygen molecules adsorbed at gold/titania perimeter sites. Superoxide species are formed more efficiently in this way than on the bare TiO2 surface. This catalytic effect of the gold nanoparticles is attributed to a weakening of the internal O-O bond, leading to a preferential splitting of the molecule at shorter bond lengths together with a 70% decrease of the dissociation free energy barrier compared to the non-catalyzed case on bare TiO2. The findings are an important step forward in the clarification of the role of gold in (photo)catalytic processes.

Thermal and Photocatalytic Reactions of Methanol and Acetaldehyde on Pt-Modified Brookite TiO2 Nanorods

The influence of adding Pt on the catalytic and photocatalytic activity of monodispersed brookite phase TiO2 (B-TiO2) nanorods (NRs) was investigated. Pt was deposited on the NRs by photodeposition in solution, and the Pt-modified NRs were characterized using XPS, STEM, and LEIS. The thermal and photocatalytic activity of the Pt-modified NRs were then evaluated using temperature-programmed desorption (TPD) in ultrahigh vacuum (UHV). It was found that while Pt primarily acted as a site blocker for thermal reactions, Pt also acted as a recombination center for photogenerated electrons and holes, resulting in suppressed photocatalytic activity. Upon pretreatment with O2, however, the Pt-modified NRs exhibited enhanced photoactivity, indicating that adsorbed oxygen prevents electron–hole recombination by reacting with photogenerated conduction band electrons from the B-TiO2 to produce stable superoxide species on the Pt surface deposits. These results clearly demonstrate how the dynamics of charge carriers at...

235 - Influence of pH on the reactions of heme peroxidase-derived oxidants with R19S

Oxidant production by heme peroxidases (such as myeloperoxidase [MPO], lactoperoxidase, eosinophil peroxidase and peroxidasin) impacts host defense and macromolecular structure and has the potential to cause tissue damage. Marked increases in phagocyte MPO, capable of producing highly reactive hypochlorous acid (HOCl), have been noted in multiple chronic inflammatory diseases. However, measuring MPO-derived oxidants at the site of production in vivo is technically challenging. The rhodamine-based probe R19S, first described by X. Chen et al (Chem Commun 2011; 47:4373-4375), becomes fluorescent R19 after reaction with HOCl but does not react with superoxide, hydrogen peroxide or several other reactive species. Thus, R19S may be useful to study MPO activity in situ. We sought to characterize the potential responses of R19S to other heme peroxidase-derived oxidants to establish whether a fluorescent response is solely indicative of HOCl or may include others. We analyzed responses of R19S to HOCl (positive control), hydrogen peroxide (negative control), hypobromous acid (HOBr), hypothiocyanous acid (HOSCN), hypoiodous acid (HOI) and taurine chloramine (TauCl) at pH 5.5 and 7.5. A similar study was recently published by A.M. Albrett et al (J Biol Chem 2018; ahead of print). Our results show strong agreement with their study at neutral pH (with a response hierarchy of HOI > HOCl > HOBr > HOSCN), although the overall responses of HOBr and HOSCN relative to HOCl were greater. At pH 5.5, we observed an altered hierarchy, with HOBr and HOI responses diminished (mean of 14.0±0.5% and 65.1±1.0% of HOCl, respectively, vs. 83.2±2.3% and 165.8±6.4% at pH 7.5), while HOSCN response was increased (93.3±5.1% of HOCl, vs. 37.6±0.2% at pH 7.5). Although TauCl did not cause fluorescence at neutral pH, modest response was detectible at acidic pH (9.8±0.2% of HOCl). These data illustrate that the environment of R19S determines its responsiveness to peroxidase-derived oxidants and should be considered when interpreting results.

114 - Two structures from a single gene: investigating the differential folding of SOD3

Extracellular superoxide dismutase (SOD3) is a zinc and copper-containing enzyme that is responsible for the dismutation of the reactive oxygen species superoxide. SOD3 has previously been shown to exist in two distinct folding variants. These variants are characterized by the connectivity of their disulfide bridges and by their enzymatic activity. One folding variant presents enzymatic activity (aSOD3), while the other, iSOD3, is enzymatically inactive. It has previously been established, that the folding of these variants is an intracellular process and not a result of extracellular regulation. However, the mechanisms involved in the folding and maturation processes have yet to be described. Therefore we aim to describe the process by which this differential folding is achieved. In order to monitor the disulfide isomerization, we have developed a mass spectrometry-based assay that will allow us to determine the ratio between iSOD3 and aSOD3 both in the secreted SOD3 pool and in SOD3 present in the intracellular space. In addition, we are currently aiming to establishing an expression assay, which supports the expression of SOD3 engineered with a specific cleavage site that will enable the differentiation between aSOD3 and iSOD3. By the use of these assays, we aim to quantify the ratio of SOD3 folding variants in cells expressing different SOD3 species as well as in cells exposed to, e.g., oxidative stress conditions.

Unprecedented direct cupric-superoxo conversion to a bis-μ-oxo dicopper(III) complex and resulting oxidative activity

Investigations of small molecule copper-dioxygen chemistry can and have provided fundamental insights into enzymatic processes (e.g., copper metalloenzyme dioxygen binding geometries and their associated spectroscopy and substrate reactivity). Strategically designing copper-binding ligands has allowed for insight into properties that favor specific (di)copper-dioxygen species. Herein, the tetradentate tripodal TMPA-based ligand (TMPA = tris((2-pyridyl)methyl)amine) possessing a methoxy moiety in the 6-pyridyl position on one arm (OCH3TMPA) was investigated. This system allows for a trigonal bipyramidal copper(II) geometry as shown by the UV–vis and EPR spectra of the cupric complex [(OCH3TMPA)CuII(OH2)](ClO4)2. Cyclic voltammetry experiments determined the reduction potential of this copper(II) species to be −0.35 V vs. Fc+/0 in acetonitrile, similar to other TMPA-derivatives bearing sterically bulky 6-pyridyl substituents. The copper-dioxygen reactivity is also analogous to these TMPA-derivatives, affording a bis-μ-oxo dicopper(III) complex, [{(OCH3TMPA)CuIII}2(O2−)2]2+, upon oxygenation of the copper(I) complex [(OCH3TMPA)CuI](B(C6F5)4) at cryogenic temperatures in 2-methyltetrahydrofuran. This highly reactive intermediate is capable of oxidizing phenolic substrates through a net hydrogen atom abstraction. However, after bubbling of the precursor copper(I) complex with dioxygen at very low temperatures (−135 °C), a cupric superoxide species, [(OCH3TMPA)CuII(O2−)]+, is initially formed before slowly converting to [{(OCH3TMPA)CuIII}2(O2−)2]2+. This appears to be the first instance of the direct conversion of a cupric superoxide to a bis-μ-oxo dicopper(III) species in copper(I)-dioxygen chemistry.

Reactivity of redox sensitive paramagnetic nitroxyl contrast agents with reactive oxygen species.

The reactivity of nitroxyl free radicals, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) and 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CmP), with reactive oxygen species (ROS) were compared as typical 6-membered and 5-membered ring nitroxyl compounds, respectively. The reactivity of the hydroxylamine forms of both these nitroxyl radicals (TEMPOL-H and CmP-H) was also assessed. Two free radical species of ROS, hydroxyl radical (•OH) and superoxide (O2•−), were subjected to a competing reaction. •OH was generated by UV irradiation from an aqueous H2O2 solution (H2O2-UV system), and O2•− was generated by a reaction between hypoxanthine and xanthine oxidase (HX-XO system). •OH and O2•− generated by the H2O2-UV and HX-XO systems, respectively, were measured by electron paramagnetic resonance (EPR) spin-trapping, and the amount of spin adducts generated by each system was adjusted to be equal. The time courses of the one-electron oxidation of TEMPOL, CmP, TEMPOL-H, and CmP-H in each ROS generation system were compared. A greater amount of TEMPOL was oxidized in the HX-XO system compared with the H2O2-UV system, whereas the reverse was observed for CmP. Although the hydroxylamine forms of the tested nitroxyl radicals were oxidized evenly in the H2O2-UV and HX-XO systems, the amount of oxidized CmP-H was approximately 3 times greater compared with TEMPOL-H.

Molecular mechanisms regarding potassium bromate‑induced cardiac hypertrophy without apoptosis in H9c2 cells.

Cardiac hypertrophy is commonly involved in cardiac injury. Oxidative stress can induce cardiac hypertrophy with apoptosis. Potassium bromate (KBrO3) has been widely used as a food additive due to its oxidizing properties. In the present study, the rat‑derived heart cell line H9c2 was used to investigate the effect of KBrO3 on cell size. KBrO3 increased cell size at concentrations <250µM, in a dose‑dependent manner. Additionally, KBrO3 also promoted the gene expression of two biomarkers of cardiac hypertrophy, brain/B‑type natriuretic peptides (BNP) and β‑Myosin Heavy Chain (β‑MHC). However, apoptosis remained unobserved in these cells. Moreover, mediation of free radicals was investigated using a fluorescence assay, and it was observed that superoxide and reactive oxygen species (ROS) levels increased with KBrO3. Effects of KBrO3 were significantly reduced by tiron at concentrations sufficient to produce antioxidant‑like action. Additionally, signals involved in cardiac hypertrophy such as calcineurin and nuclear factor of activated T‑cells (NFAT) were also determined using western blot analysis. KBrO3 increased the protein levels of both these molecules which were decreased by tiron in a dose‑dependent manner. Additionally, cyclosporine A attenuated the cardiac hypertrophy induced by KBrO3 in H9c2 cells at concentrations effective to inhibit calcineurin, in addition to reducing mRNA levels of BNP or β‑MHC. Finally, apoptosis was also identified in H9c2 cells incubated with KBrO3 at concentrations >300µM. Collectively, these results provided a novel perspective that KBrO3 induces cardiac hypertrophy without apoptosis at a low dose through the generation of ROS, activating the calcineurin/NFAT signaling pathway in H9c2 cells. Therefore, at a dose <250µM, KBrO3 can be applied as an inducer of cardiac hypertrophy without apoptosis in H9c2 cells. KBrO3 can also be developed as a tool to induce cardiac hypertrophy in animals.

Preparation of novel flower-like BiVO4/Bi2Ti2O7/Fe3O4 for simultaneous removal of tetracycline and Cu2+: Adsorption and photocatalytic mechanisms

To improve the visible light utilization and adsorption capacity for combined pollutants (Tetracycline and Cu2+), novel flower-like BiVO4/Bi2Ti2O7/Fe3O4 composite has been successfully synthesized for the first time via a simple two-step process, surfactant-free hydrothermal route and solvothermal method. The crystal structures, chemical compositions, morphologies, optical and photocatalytic properties of the as-prepared samples were characterized by the techniques of XRD, XPS, SEM, HRTEM, BET, UV–vis DRS, and Photocurrent tests (PT). The synthetic sample with 4:1:20 (S5) mass ratio of BiVO4/Bi2Ti2O7/Fe3O4 possessed the highest adsorption capacity and photocatalytic performance simultaneously in all of the as-prepared composites. Adsorption experiment (model 1 and model 2) suggested that there was not only competitive adsorption but also synergistic adsorption mechanisms between Cu2+ and TC. Compared to pure BiVO4, and BiVO4/Bi2Ti2O7, BiVO4/Bi2Ti2O7/Fe3O4 displayed more superior photodegradation efficiency with 97.22% removal of TC (10 mg/L) in 60 min, where the optimal conditions were catalyst dosage 1.00 g/L and initial pH at 6.0. In addition, radical trapping experiments revealed that the photo-induced active species superoxide radical (O2−) and holes (h+) were the predominant active species in the photocatalytic system. These features demonstrate that the BiVO4/Bi2Ti2O7/Fe3O4 has great application potential for combined pollutants’ removal from water.

Abstract A52: Potassium channel activator minoxidil (Rogaine) as a novel single-agent or combination therapy in ovarian cancer

Abstract Recent advances in cancer therapy treatments for ovarian cancer have been severely hindered by limited drug availability, excessive side effects, and drug resistance and the difficulty in finding and targeting proteins governing important events in ovarian cancer cells. Novel therapeutic agents targeting specific molecular pathways involved in ovarian cancer are urgently needed. During our investigation to identify new and critical targets in cancer, we found a novel role for the potassium ion channel Kir6.2 in ovarian cancer cells. Our bioinformatics investigation showed that Kir6.2 is expressed in ovarian cancers. We discovered that stimulation of the Kir6.2 channel activity with the small molecule minoxidil (Rogaine®) produces a strong inhibition on ovarian cancer cells’ growth. However, minoxidil had no significant effects on cells that do not express Kir6.2. We describe a biochemical signaling linking activation of Kir6.2 potassium channel to the tumor suppressor mechanism, which includes a Ca2+-dependent production of superoxide species (ROS), which leads to a significant increase of DNA damage. Consequently, cells die upon activation of apoptosis via caspase-3. Minoxidil is an FDA-approved drug that presents very limited side effects. Therefore, our data are important because for the first time they reveal that use of the Kir6.2 potassium channel activator, e.g., Rogaine®, could be considered as a potential single-agent novel treatment for ovarian cancer. Clinicians’ approaches for treating advanced ovarian cancer patients are strongly limited by the concern that current chemotherapeutic agent will raise toxicity. For example, although genotoxic chemotherapeutic agents such as doxorubicin or platinum-containing molecules of carboplatin are among the most effective drug classes in ovarian cancer, dose-dependent toxicity of these agents is often the cause for interrupting the treatment. Our experiments demonstrated that the Kir6.2 activator minoxidil potentiates the antineoplastic effects of doxorubicin as well as of carboplatin by exacerbating their DNA-damaging effects. This discovery is important because it offers the opportunity to design a clinically effective therapeutic strategy in which minoxidil could be administered in combination with genotoxic agents to limit their toxicity in ovarian cancer patients. Citation Format: Daniela Fukushiro-Lopes, Megan Jain, Maryam Khalid, Alexandra Hegel, Saverio Gentile. Potassium channel activator minoxidil (Rogaine) as a novel single-agent or combination therapy in ovarian cancer. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A52.

Improved Li–Metal Cycling Performance in High Concentrated Electrolytes for Li‐O2 Batteries

AbstractSince the carbonate‐solvents used in Li‐ion batteries were incompatible for Li‐O2 electrochemistry, alternatives have been investigated recently. Dimethyl sulfoxide (DMSO) stands among the best solvents for the Li‐O2 system owing to its comparative stability against the superoxide and peroxide species formed during cell discharge. However, it has a drawback of instability towards metallic lithium. Recent reports suggest the use of concentrated electrolytes that prevent solvent decomposition via shielding from lithium‐metal. Herein, LiTFSI/DMSO is chosen as salt/solvent configuration with 3 salt concentrations. The solution properties, namely ionic conductivity, Li‐transference number, and viscosity are studied along with electrochemical properties such as Li‐stripping/plating coulombic efficiency and symmetrical long‐term cycling. It is shown that concentrated electrolytes (&gt;1 M) exhibit superior cycling stability and coulombic efficiency. Post cycling analysis on electrodes confirms solvent decomposition only in low concentrated electrolyte. Moreover, the presence of oxygen in concentrated solutions yields an even better cycling stability than oxygen free electrolyte.

Enhanced photocatalytic activity of a novel NiO/Bi2O3/Bi3ClO4 nanocomposite for the degradation of azo dye pollutants under visible light irradiation

In this work, a novel NiO/Bi2O3/Bi3ClO4 heterojunction nanocomposite with high visible-light-driven photocatalytic performance has been fabricated via an improved Pechini sol-gel method. The results exhibited that by controlling the process parameters such as kind of carboxylic acids, gelling agents and molar ratio of carboxylic acid to metals, the NiO/Bi2O3/Bi3ClO4 nanocomposites with various morphologies were synthesized. Furthermore, compared to pure NiO/Bi2O3 and other nanocomposites, NiO/Bi2O3/Bi3ClO4 demonstrated more photodegradation efficiency with 89% removal of acid red 88 azo dye in 120 min under visible light irradiation after four times cycles. The enhanced photocatalytic performance can be attributed to the effective separation and transfer of the photoexcited electron-hole pairs, fine particle size distribution and favorable absorption capability of NiO/Bi2O3/Bi3ClO4 ternary nanocomposite. In addition, the reliable photocatalytic mechanism was explained on the basis of the radical trapping experiment, which revealed the photoinduced active species superoxide radicals and holes were the prevailing active species in the photocatalytic process.

Simultaneous Stabilization of Potassium Metal and Superoxide in K-O2 Batteries on the Basis of Electrolyte Reactivity.

In superoxide batteries based on O2 /O2- redox chemistry, identifying an electrolyte to stabilize both the alkali metal and its superoxide remains challenging owing to their reactivity towards the electrolyte components. Bis(fluorosulfonyl)imide (FSI- ) has been recognized as a "magic anion" for passivating alkali metals. The KFSI-dimethoxyethane electrolyte passivates the potassium metal anode by cleavage of S-F bonds and the formation of a KF-rich solid-electrolyte interphase (SEI). However, the KFSI salt is chemically unstable owing to nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable to KO2 , but results in mossy potassium deposits and irreversible plating and stripping. To circumvent this dilemma, we developed an artificial SEI for the metal anode and thus long-cycle-life K-O2 batteries. This study will guide the development of stable electrolytes and artificial SEIs for metal-O2 batteries.

Simultaneous Stabilization of Potassium Metal and Superoxide in K–O2 Batteries on the Basis of Electrolyte Reactivity

AbstractIn superoxide batteries based on O2/O2− redox chemistry, identifying an electrolyte to stabilize both the alkali metal and its superoxide remains challenging owing to their reactivity towards the electrolyte components. Bis(fluorosulfonyl)imide (FSI−) has been recognized as a “magic anion” for passivating alkali metals. The KFSI–dimethoxyethane electrolyte passivates the potassium metal anode by cleavage of S−F bonds and the formation of a KF‐rich solid–electrolyte interphase (SEI). However, the KFSI salt is chemically unstable owing to nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable to KO2, but results in mossy potassium deposits and irreversible plating and stripping. To circumvent this dilemma, we developed an artificial SEI for the metal anode and thus long‐cycle‐life K–O2 batteries. This study will guide the development of stable electrolytes and artificial SEIs for metal–O2 batteries.

Bio-conjugated N-(2-hydroxy-1-naphthaldehyde)-glucosamine Cu(II) complex: Bacterial sensitivity and superoxide dismutase-like activity

Bacterial sensitivity and super-oxide dismutase (SOD) activity of sugar Schiff base complexes represent great fascinating areas of research. Under such curiosity, herein a new glucosamine Schiff base Cu(II) complex of N-(2-hydroxy-1-naphthaldehyde)-glucosamine is reported. The compound has been characterized on the basis of various physicochemical techniques in association with density functional theory (DFT) approach. Becke-3-Lee-Yang-Parr (B3LYP)/Los Alamos National Laboratory 2 Double Z (LanL2DZ) specified of Cu atom and 6311G/B3LYP for all other atoms were applied for the theoretical analysis. From the study, experimental observations and theoretical outcomes have been found in close agreement with one another. A suitable square planar geometry has been suggested for the complex. Moreover, the Schiff base ligand and its metal complex were screened for the broad spectrum antibacterial sensitivity and SOD activity. Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Salmonella typhus were the bacterial strains selected for the antimicrobial tests. From the measurement of inhibition zones, it is clear that the model compound is not so much bactericidal against the selected microbes. However, due to well-pronounced results obtained under SOD assay, the complex could be suggested for in vivo practice for detoxification of superoxide species.