Salicylhydroxamic Acid Research Articles

Application of a laccase-catalyzed oxidative coupling for the removal and detoxification of typical flotation reagent salicylhydroxamic acid

Residual organic flotation reagents in mineral processing wastewater (MPW) can pose environmental hazards and hinder the sustainable development of the mining industry. Laccase as a versatile biocatalyst can eliminate various recalcitrant contaminants from the environment, but its potential applications for the removal and detoxification of organic flotation reagents have until now been overlooked. Herein, the influence of superparamagnetic immobilized laccase (SPM-IMLac) on the enzymatic removal of salicylhydroxamic acid (SHA), a typical mineral flotation reagent, as well as the mechanism of this process have been explored for the first time. The results indicated that SPM-IMLac can effectively remove SHA over a broad pH range and this process follows the pseudo-first-order reaction kinetics. A methodology which combined high resolution mass spectrometry (HRMS) and a solid phase extraction (SPE) technique revealed that SPM-IMLac could catalyze a single-electron oxidation of SHA to generate self/cross-oligomers via radical-driven C-C and/or C-O-C covalent coupling pathways. The Vibrio fischeri bioluminescence inhibition assay and a total organic carbon (TOC) analysis corroborated that the SHA transformation was accompanied by detoxification and by a reduction in TOC of the reaction solution, the extent of which correlated with the extent of the oxidative coupling. Moreover, SPM-IMLac could be easily recovered and reused, while keeping its high removal efficiency of SHA in the actual MPW matrices. This study not only provides fascinating insights into the transformation mechanisms and environmental fate of SHA mediated by SPM-IMLac, but it also exploits a viable and sustainable approach for the remediation of organic flotation reagents-contaminated MPW.

Chemical management strategies for halo blight of hop and in vitro sensitivity of Diaporthe humulicola populations to various fungicide classes.

Halo blight of hop, caused by Diaporthe humulicola, has increased in eastern North America since 2018. When left untreated, the disease can cause yield loss ranging from 17-56%. Currently, there are no fungicides registered for use on halo blight of hop. From 2020 to 2022 field trials were conducted using 10 fungicides registered for use on powdery and downy mildew of hop to determine their efficacy against halo blight. To validate field results, the EC50 value was determined for each active ingredient including flutriafol, tebuconazole + fluopyram, cyflufenamid, and trifloxystrobin + salicylhydroxamic acid (SHAM). Each fungicide tested had an EC50 value less than 50 ppm. A discriminatory dose was used to test the sensitivity of 206 D. humulicola isolates collected from the eastern U.S. and Canada in a poison agar assay. Results showed that tebuconazole + fluopyram decreased the incidence and severity of halo blight in the field. Also, this fungicide combination had EC50 values of 2.26 x 10-1 ppm and significantly reduced the growth of most of the isolates tested. Trifloxystrobin + SHAM decreased the presence of halo blight in the field tiral, but some isolates were less sensitive in discriminatory dose testing. Our results show that fungicides in FRAC groups 3, 7, and 11 were the most effective to control halo blight. Analyses of field trials showed a positive correlation between the severity of early season downy mildew infections and late season halo blight infections.

Potential Trypanocidal Activity of Glycerol Analogues.

Glycerol, a versatile and ubiquitous compound, plays a vital role in a plethora of metabolic pathways in both prokaryotes and eukarotyes. Relatively few glycerol analogues have previously been explored for their use as glycerol kinase inhibitors, in addition to their therapeutic potential, however their use as (pro)-drugs in the context of parasitic diseases such as trypanosomiasis is unreported. The literature on glycerol metabolism and particular its synergic anti-profilation behaviour with salicylhydroxamic acid (SHAM) in Trypanosoma brucei is extensive. However, utiliation of glycerol analogues has not been explored as possible superior combinatory compounds. This report describes the synthesis of various glycerol analogues and their subsequent biochemical pheotypic analysis for their effect on lipid metabolism and their possible synergic activity with SHAM on Trypanosoma brucei. The glycerol analogues caused morphological changes;, including detached flagella, cytokinesis defects and 'big-eye' phenotype. All four compounds either matched or marginally increased the toxicity of SHAM when used in combination against Trypanosoma brucei. However, the compounds exhibited mostly an antagonistic relationship with SHAM rather than synergistic. This research highlights the potential of small molecule glycerol analogues for their combination use with SHAM for the treatment of parasitic disease, such as trypanosomiasis.

Experimental and Computational Investigation of Salicylhydroxamic Acid as a Corrosion Inhibitor for Copper in Alkaline Solutions

Inhibitors, as indispensable components in chemical mechanical polishing (CMP) slurries, have a significant impact on inhibiting copper (Cu) corrosion and enhancing post-polishing surface quality. However, one of the major challenges in CMP lies in unraveling the microscopic corrosion inhibition mechanism of Cu. This work focuses on investigating the impact of an inhibitor, salicylhydroxamic acid (SHA), on the static etching rate (SER), electrochemical parameters, and surface morphology of Cu. The experimental findings demonstrate that SHA significantly decreases the SER and corrosion current density of Cu, while notably improving the Cu surface quality. The corrosion inhibition mechanisms of SHA on Cu are revealed through adsorption isotherm models, contact angle analysis, electrochemical impedance spectroscopy, and computational chemistry method. The benzene ring, oxime group, and O1 atom of SHA exhibit significant chemical reactivity, facilitating the preferential adsorption of SHA on Cu in a parallel orientation, thereby forming a hydrophobic protective film on the Cu surface. This process hinders the interaction between corrosive solutions and Cu, therefore SHA exhibits excellent corrosion inhibition performance on Cu. These findings hold great importance in gaining a deeper comprehension of the corrosion inhibition process of Cu, and provide guidance for designing more efficient inhibitors.

Mitochondria dysfunction is one of the causes of diclofenac toxicity in the green alga Chlamydomonas reinhardtii.

Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac (DCF), form a significant group of environmental contaminants. When the toxic effects of DCF on plants are analyzed, authors often focus on photosynthesis, while mitochondrial respiration is usually overlooked. Therefore, an in vivo investigation of plant mitochondria functioning under DCF treatment is needed. In the present work, we decided to use the green alga Chlamydomonas reinhardtii as a model organism. Synchronous cultures of Chlamydomonas reinhardtii strain CC-1690 were treated with DCF at a concentration of 135.5 mg × L-1, corresponding to the toxicological value EC50/24. To assess the effects of short-term exposure to DCF on mitochondrial activity, oxygen consumption rate, mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (mtROS) production were analyzed. To inhibit cytochrome c oxidase or alternative oxidase activity, potassium cyanide (KCN) or salicylhydroxamic acid (SHAM) were used, respectively. Moreover, the cell's structure organization was analyzed using confocal microscopy and transmission electron microscopy. The results indicate that short-term exposure to DCF leads to an increase in oxygen consumption rate, accompanied by low MMP and reduced mtROS production by the cells in the treated populations as compared to control ones. These observations suggest an uncoupling of oxidative phosphorylation due to the disruption of mitochondrial membranes, which is consistent with the malformations in mitochondrial structures observed in electron micrographs, such as elongation, irregular forms, and degraded cristae, potentially indicating mitochondrial swelling or hyper-fission. The assumption about non-specific DCF action is further supported by comparing mitochondrial parameters in DCF-treated cells to the same parameters in cells treated with selective respiratory inhibitors: no similarities were found between the experimental variants. The results obtained in this work suggest that DCF strongly affects cells that experience mild metabolic or developmental disorders, not revealed under control conditions, while more vital cells are affected only slightly, as it was already indicated in literature. In the cells suffering from DCF treatment, the drug influence on mitochondria functioning in a non-specific way, destroying the structure of mitochondrial membranes. This primary effect probably led to the mitochondrial inner membrane permeability transition and the uncoupling of oxidative phosphorylation. It can be assumed that mitochondrial dysfunction is an important factor in DCF phytotoxicity. Because studies of the effects of NSAIDs on the functioning of plant mitochondria are relatively scarce, the present work is an important contribution to the elucidation of the mechanism of NSAID toxicity toward non-target plant organisms.

A multiplexed high throughput screening assay using flow cytometry identifies glycolytic molecular probes in bloodstream form Trypanosoma brucei

Kinetoplastid organisms, including Trypanosoma brucei, are a significant health burden in many tropical and semitropical countries. Much of their metabolism is poorly understood. To better study kinetoplastid metabolism, chemical probes that inhibit kinetoplastid enzymes are needed. To discover chemical probes, we have developed a high-throughput flow cytometry screening assay that simultaneously measures multiple glycolysis-relevant metabolites in live T. brucei bloodstream form parasites. We transfected parasites with biosensors that measure glucose, ATP, or glycosomal pH. The glucose and ATP sensors were FRET biosensors, while the pH sensor was a GFP-based biosensor. The pH sensor exhibited a different fluorescent profile from the FRET sensors, allowing us to simultaneously measure pH and either glucose or ATP. Cell viability was measured in tandem with the biosensors using thiazole red. We pooled sensor cell lines, loaded them onto plates containing a compound library, and then analyzed them by flow cytometry. The library was analyzed twice, once with the pooled pH and glucose sensor cell lines and once with the pH and ATP sensor cell lines. Multiplexing sensors provided some internal validation of active compounds and gave potential clues for each compound's target(s). We demonstrated this using the glycolytic inhibitor 2-deoxyglucose and the alternative oxidase inhibitor salicylhydroxamic acid. Individual biosensor-based assays exhibited a Z′-factor value acceptable for high-throughput screening, including when multiplexed. We tested assay performance in a pilot screen of 14,976 compounds from the Life Chemicals Compound Library. We obtained hit rates from 0.2 to 0.4% depending on the biosensor, with many compounds impacting multiple sensors. We rescreened 44 hits, and 28 (64%) showed repeatable activity for one or more sensors. One compound exhibited EC50 values in the low micromolar range against two sensors. We expect this method will enable the discovery of glycolytic chemical probes to improve metabolic studies in kinetoplastid parasites.

A self-assembled surfactant for efficient flotation of cassiterite: Experimental study and DFT calculation

Surfactants of different kinds are important in the flotation of metal oxide ores. In this paper, a combined organic surfactant was formed through self-assembly of salicylhydroxamic acid (SHA) and isopropanolamine dodecylbenzenesulfonate (DBIA). The effects of SHA and DBIA on the flotation behavior of cassiterite were investigated. Density functional theory (DFT) calculations were used to clarify the microscopic adsorption mechanism of SHA and DBIA on the cassiterite surface. The flotation performance of the combined surfactant was investigated to determine the optimum ratio. Subsequently, the self-assembly behavior of the surfactants in aqueous solutions was examined using surface tension tests and molecular dynamics simulations. Flotation experiments and zeta potential, X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), contact angle, and adsorption capacity analyses were used to explore the flotation behavior and adsorption mechanism at the solid–liquid–gas boundary. The maximum flotation recovery of cassiterite were 45.73 % and 71.25 % when SHA and DBIA were used alone. By contrast, with the developed combined surfactant, the flotation recovery at the same reagent concentration was 84.92 %. The SHA/DBIA surfactant co-adsorbed at the aqueous solution interface, which decreased the surface tension of the solution to 4.943 × 10−4 mol/L and resulted in formation of a stable foam layer. These effects altered the surface properties of cassiterite and enhanced its surface hydrophobicity. Overall, this study provides valuable mechanistic insights into the enhanced chelation complexation of self-assembled surface collectors with metal oxides.

BomMDH1 regulates malate-mediated oxidative stress in tobacco BY-2 suspension cells

Programmed cell death (PCD) is a genetically regulated process of cell suicide essential for plant development. The ‘malate valve’ is a mechanism that ensures redox balance across different subcellular compartments. In broccoli, the BomMDH1 gene encodes malate dehydrogenase in mitochondria, a critical enzyme in the ‘malate circulation’ pathway. This study investigates the functional role of BomMDH1 in malate (MA)-induced apoptosis in bright yellow-2 (BY-2) suspension cells. Findings revealed that transgenic cells overexpressing BomMDH1 showed enhanced viability under MA-induced oxidative stress compared to wild-type (WT) cells. Overexpression of BomMDH1 also reduced levels of reactive oxygen species (ROS), hydrogen peroxide (H2O2), and malondialdehyde (MDA), while increasing the expression of antioxidant enzyme genes such as NtAPX, NtAOX1a, NtSOD, and NtMDHAR. Additionally, treatment with salicylhydroxamic acid (SHAM), a characteristic inhibitor of mitochondrial respiration, further improved the anti-apoptotic activity of BY-2 cells. Overall, these results highlighted the function of the BomMDH1 gene and the potential of SHAM treatment in mitigating oxidative stress in BY-2 suspension cells.

Peroxidase in plant defense: Novel insights for cadmium accumulation in rice (Oryza sativa L.)

Phenylpropanoid biosynthesis plays crucial roles in the adaptation to cadmium (Cd) stress. Nevertheless, few reports have dabbled in physiological mechanisms of such super pathway regulating Cd accumulation in plants. Herein, by integrating transcriptomic, histological and molecular biology approaches, the present study dedicated to clarify molecular mechanism on how rice adapt to Cd stress via phenylpropanoid biosynthesis. Our analysis identified that the enhancement of phenylpropanoid biosynthesis was as a key response to Cd stress. Intriguingly, POD occupied a significant part in this process, with the number of POD related genes accounted for 26/29 of all upregulated genes in phenylpropanoid biosynthesis. We further used SHAM (salicylhydroxamic acid, the POD inhibitor) to validate that POD exhibited a negative correlation with the Cd accumulation in rice tissues, and proposed two intrinsic molecular mechanisms on POD in contributing to Cd detoxification. One strategy was that POD promoted the formation of lignin and CSs both in endodermis and exodermis for intercepting Cd influx. In detail, inhibited POD induced by external addition of SHAM decreased the content of lignin by 50.98–66.65 % and delayed percentage of the DTIP-CS to root length by 39.17–104.51 %. The other strategy was expression of transporter genes involved in Cd uptake, including OsIRT1, OsIRT2, OsZIP1 and OsZIP, negatively regulated by POD. In a word, our findings firstly draws a direct link between POD activity and the Cd accumulation, which is imperative for the breeding of rice with low-Cd-accumulating capacity in the future.

Synergistic effect of salicylhydroxamic acid in quinone outside inhibitor fungicides and its sensitivity on fruit rot pathogens

Synergistic effect of salicylhydroxamic acid in quinone outside inhibitor fungicides and its sensitivity on fruit rot pathogens

High resistance risk of Phytophthora colocasiae to azoxystrobin in southeastern of China

Quinone outside inhibitor (QoI) has been applied to manage taro leaf blight caused by Phytophthora colocasiae in southeastern of China for many years. The risk of P. colocasiae to QoI and the potential resistant mechanism remain unknown. In this study, the 74 P. colocasiae strains were sampled from southeastern of China. Sequence analysis of the QoI target Cytb showed one nucleotide variant in the fragment of this gene in this population, producing two haplotypes. The nucleotide variant leads to codon change at 142 (GGT to GCT) producing A142 (alanine) and G142 (glycine) in Hap_1 and Hap_2 strains, respectively. The sensitivity differentiation to azoxystrobin of two haplotypes were observed in vitro. The Hap_1 and Hap_2 strains were confirmed resistant and sensitive by control efficacy of label rate fungicide application, which was 3.0% and 88.8% treated with 500 μg/mL azoxystrobin, respectively. In addition, 10.0 μg/mL azoxystrobin plus 50 μg/mL salicylhydroxamic acid (SHAM) supplemented in PDA medium was identified as a discriminatory dose for differentiation of these two phenotype strains. The azoxystrobin resistant frequency reached 86.5%, indicating prevalence of QoI resistance in the field. Further fitness related features showed that no significant difference in temperature sensitivity, mycelial growth rate, sporangia production, zoospore release and aggressiveness between azoxystrobin-resistant and sensitive strains indicating no potential fitness cost for azoxystrobin resistance. Taken together, azoxystrobin resistance need to be taken into consideration to manage taro leaf blight in southeastern of China.

Revisiting the intron hypothesis of QoI resistance in Phyllosticta ampelicida, the causal agent of grape black rot, and other Phyllosticta species

AbstractChemical control of grape black rot, caused by Phyllosticta ampelicida, relies mainly on the use of demethylation inhibitors (DMIs) and quinone outside inhibitors (QoIs). The effectiveness of QoI fungicides is influenced by alternative respiration activity, and the exon/intron structure and point mutations in the target protein's gene, the cytochrome b (cytb) gene. Our study aims to investigate the QoI fungicide sensitivity of 48 P. ampelicida isolates in vitro by measuring EC50 and the molecular characteristics of the cytb gene and its mRNA in P. ampelicida and other Phyllosticta species. Mycelial growth tests revealed that the P. ampelicida isolates were sensitive to both azoxystrobin and trifloxystrobin; baseline EC50 values were 0.029 and 0.022 μg/mL, respectively. Addition of salicylhydroxamic acid (SHAM) resulted in lower EC50 values (0.024 and 0.017 μg/mL, respectively). None of the typical point mutations conferring resistance to QoIs in some fungi were detected. A group I intron was present right after the 143rd codon in the cytb gene in four of the six Phyllosticta species examined. The sequence and exon/intron structure of the cytb gene of P. ampelicida isolated from Vitis vinifera is studied in detail and published here. Our results indicate a low risk of QoI resistance development via the G143A mutation in P. ampelicida.

Insights into the changes in the surface properties of goethite with Ni in the lattice in the presence of salicylhydroxamic acid: Experimental and density functional theory studies

Insights into the changes in the surface properties of goethite with Ni in the lattice in the presence of salicylhydroxamic acid: Experimental and density functional theory studies

Multinuclear Tin-Based Macrocyclic Organometallic Resist for EUV Photolithography.

We report a new photoresist based on a multinuclear tin-based macrocyclic complex and its performance for extreme UV (EUV) photolithography. The new photoresist has a trinuclear macrocyclic structure containing three salicylhydroxamic acid ligands and six Sn-CH3 bonds, which was confirmed by multinuclear nuclear magnetic resonance (NMR) and FT-IR spectroscopies and single-crystal X-ray diffraction study. The resist exhibited good humidity, air, and thermal stabilities, while showing good photochemical reactivity. Photochemical cross-linking of the resist was confirmed by X-ray photoelectron and solid-state NMR spectroscopic analyses. EUV photolithography with the 44 nm-thick film on a silicon wafer revealed a line-edge-roughness (LER) of 1.1 nm in a 20 nm half-pitch pattern. The Z-factor, a metric that gauges the performance of photoresists by considering the tradeoff between resolution, LER, and sensitivity (RLS), was estimated to be 1.28 × 10-8 mJ·nm3, indicating its great performance compared to the EUV photoresists reported in the literature.

Improvement of Panax notoginseng saponin accumulation triggered by methyl jasmonate under arbuscular mycorrhizal fungi.

Panax notoginseng is a highly valued perennial medicinal herb plant in Yunnan Province, China, and the taproots are the main medicinal parts that are rich in active substances of P. notoginseng saponins. The main purpose of this study is to uncover the physiological and molecular mechanism of Panax notoginseng saponin accumulation triggered by methyl jasmonate (MeJA) under arbuscular mycorrhizal fungi (AMF) by determining physiological indices, high-throughput sequencing and correlation analysis. Physiological results showed that the biomass and saponin contents of P. notoginseng, the concentrations of jasmonic acids (JAs) and the key enzyme activities involved in notoginsenoside biosynthesis significantly increased under AMF or MeJA, but the interactive treatment of AMF and MeJA weakened the effect of AMF, suggesting that a high concentration of endogenous JA have inhibitory effect. Transcriptome sequencing results indicated that differential expressed genes (DEGs) involved in notoginsenoside and JA biosynthesis were significantly enriched in response to AMF induction, e.g., upregulated genes of diphosphocytidyl-2-C-methyl-d-erythritol kinases (ISPEs), cytochrome P450 monooxygenases (CYP450s)_and glycosyltransferases (GTs), while treatments AMF-MeJA and salicylhydroxamic acid (SHAM) decreased the abundance of these DEGs. Interestingly, a high correlation presented between any two of saponin contents, key enzyme activities and expression levels of DEGs. Taken together, the inoculation of AMF can improve the growth and saponin accumulation of P. notoginseng by strengthening the activities of key enzymes and the expression levels of encoding genes, in which the JA regulatory pathway is a key link. This study provides references for implementing ecological planting of P. notoginseng, improving saponin accumulation and illustrating the biosynthesis mechanism.

Flotation performance of a novel collector, ethyl o-mesitylsulfonylacetohydroxamate, for bastnaesite ores

Existing collectors used in the flotation process of bastnaesite ores are characterized by the poor flotation performance and low recovery. In this paper, from the perspective of molecular structure, ethyl O-mesitylsulfonylacetohydroxamate (C<sub>1</sub>) was selected as a novel collector for bastnaesite ores, and compared with the most commonly used collector, salicylhydroxamic acid (C<sub>2</sub>), in the flotation test with bastnaesite ore with fine mineral particles, complex embedding and a high mud content. The flotation test confirmed that C<sub>1</sub> had the better collection ability and flotation performance than C<sub>2</sub>. Then, the adsorption mechanisms between collectors (C<sub>1</sub> and C<sub>2</sub>) and bastnaesite surface were explored based on first principles thinking. The adsorption energies between collectors (C<sub>1</sub> and C<sub>2</sub>) and the (110) plane of bastnaesite were respectively calculated as -1.79 eV and -1.44 eV and corresponding adsorption heights were respectively 1.65 Å and 2.43 Å. These data indicated that C<sub>1</sub> had the better affinity to the (110) plane of bastnaesite and the better binding. The calculation results of partial density of states (PDOS) showed that both collectors underwent significant orbital hybridization with the (110) plane of bastnaesite, suggesting strong electronic interactions.

UV Laser-Induced Photodecomposition of Matrix-Isolated Salicylhydroxamic Acid: Identification of New Isocyanate Complexes.

Photochemical reactions of salicylhydroxamic acid were induced using tunable UV laser radiation followed by FTIR spectroscopy. Four pairs of co-products were experimentally found to appear in the photolysis: C6H4(OH)NCO⋯H2O (1), C6H4(OH)C(O)N⋯H2O (2), C6H4(OH)2⋯HNCO (3), and C6H4(OH)NHOH⋯CO (4). The comparison of the theoretical spectra with the experimental ones allowed us to determine the structures of the complexes formed in the matrices. The mechanisms of the reaction channels leading to the formation of the photoproducts were proposed. It was concluded that the first step in the formation of the complexes (1), (2), and (3) was the scission of the N-O bond, whereas the creation of complex (4) was due to cleavage of the C-N bond.

Helicobacter pylori secretory Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation

Helicobacter pylori-associated stomach infection is a leading cause of gastric ulcer and related cancer. H. pylori modulates the functions of infiltrated immune cells to survive the killing by reactive oxygen and nitrogen species (ROS and RNS) produced by these cells. Uncontrolled immune responses further produce excess ROS and RNS which lead to mucosal damage. The persistent oxidative stress is a major cause of gastric cancer. H. pylori regulates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), nitric oxide synthase 2 (NOS2), and polyamines to control ROS and RNS release through lesser-known mechanisms. ROS and RNS produced by these pathways differentiate macrophages and T cells from protective to inflammatory phenotype. Pathogens-associated molecular patterns (PAMPs) induced ROS activates nuclear oligomerization domain (NOD), leucine rich repeats (LRR) and pyrin domain-containing protein 3 (NLRP3) inflammasome for the release of pro-inflammatory cytokines. This study evaluates the role of H. pylori secreted concentrated proteins (HPSCP) related oxidative stress role in NLRP3 inflammasome activation and macrophage differentiation. To perceive the role of ROS/RNS, THP-1 and AGS cells were treated with 10 μM diphenyleneiodonium (DPI), 50 μM salicyl hydroxamic acid (SHX), 5 μM Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP), which are specific inhibitors of NADPH oxidase (NOX), Myeloperoxidase (MPO), and mitochondrial oxidative phosphorylation respectively. Cells were also treated with 10 μM of NOS2 inhibitor l-NMMA and 10 μM of N-acetyl cysteine (NAC), a free radical scavenger·H2O2 (100 μM) treated and untreated cells were used as positive controls and negative control respectively. The expression of gp91phox (NOX2), NOS2, NLRP3, CD86 and CD163 was analyzed through fluorescent microscopy. THP-1 macrophages growth was unaffected whereas the gastric epithelial AGS cells proliferated in response to higher concentration of HPSCP. ROS and myeloperoxidase (MPO) level increased in THP-1 cells and nitric oxide (NO) and lipid peroxidation significantly decreased in AGS cells. gp91phox expression was unchanged, whereas NOS2 and NLRP3 downregulated in response to HPSCP, but increased after inhibition of NO, ROS and MPO in THP-1 cells. HPSCP upregulated the expression of M1 and M2 macrophage markers, CD86 and CD163 respectively, which was decreased after the inhibition of ROS.This study concludes that there are multiple pathways which are generating ROS during H. pylori infection which further regulates other cellular processes. NO is closely associated with MPO and inhibition of NLRP3 inflammasome. The low levels of NO and MPO regulates gastrointestinal tract homeostasis and overcomes the inflammatory response of NLRP3. The ROS also plays crucial role in macrophage polarization hence alter the immune responses duing H. pylori pathogenesis.

Synthesis and characterization of hydroxamic acid N,3-dihydroxy-2-naphthamide and its copper (II) complex per keto/enol forms and rare earth flotation

Flotation is the most common beneficiation process used for separating minerals, but for rare earth minerals (REMs), performance can suffer due to the dilute nature of the rare earth elements. Furthermore, the REMs tend to possess smaller grain sizes, making the use of traditional flotation cells difficult if total liberation is needed. Consequently, improved efficiencies are needed for extracting REMs from various sources. For these systems, hydroxamic acids are commonly used as flotation collectors. Two such hydroxamic collectors were studied in this work: salicylhydroxamic acid (SHA) and N,3-dihydroxy-2-naphthamide (H2O5). Because there is no documented synthesis route for H2O5, several synthesis approaches were examined. Furthermore, because there is no information on H2O5, important structural and characteristic data was gathered regarding its (1) preferred structural isomer as a Cu2+ complex and (2) electrostatic potential values of the possible dentate groups in different tautomeric forms, thereby allowing H2O5 to be compared to SHA, particularly regarding flotation behavior. Hydrogen nuclear magnetic resonance (H-NMR), Laser Raman Spectroscopy (LRS), and predominantly Fourier-Transform Infrared (FT-IR) spectroscopy showed that both SHA and H2O5 preferred to be keto tautomers when uncomplexed; however, once chelated to Cu2+ ions, the collectors adopted enol forms. Molecular modeling using Spartan software showed an increase in the electrostatic potential of the possible dentate groups in both molecules for the enol form. H2O5 also resulted in an increased recovery by flotation of REMs of about 23% compared to SHA at similar reagent dosages.

Adsorption of salicyl hydroxamic acid and octyl hydroxamic acid mixture on the cassiterite minerals

Salicylhydroxamic acid (SHA) and octyl hydroxamic acid (OHA) are two commonly used hydroxamic acid-based collectors in fine cassiterite flotation. While some reports suggest that a mixture of OHA and SHA yields superior results compared to their individual use, there is a lack of experimental exploration and theoretical analysis. In this study, the flotation performance and the associated adsorption mechanism of SHA, OHA and their mixture on fine cassiterite particles was systematically investigated. The results demonstrate a synergistic effect between SHA and OHA in enhancing fine cassiterite flotation, with the most significant enhancement occurring at a 1:1 mass ratio under the natural pH conditions. This finding is corroborated by contact angle and zeta potential tests. When both SHA and OHA are present, SHA likely attaches to the cassiterite surface via chemisorption in the form of a five-membered chelate ring, while OHA adheres through physical adsorption, primarily establishing hydrogen bonds with oxygen sites on the cassiterite surface or with SHA molecules. The adsorption ratio of SHA to OHA onto cassiterite surfaces is approximately 69%: 31% when an equal mass of SHA and OHA interact with cassiterite under the natural pH condition.