Ethidium Research Articles

Overexpression of outer membrane protein A (OmpA) increases aminoglycoside sensitivity in mycobacteria.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) complex infection, is a leading cause of death worldwide from a single infectious agent. The emergence of drug resistance Mtb clinical strains makes the situation more serious. The role of Mtb outer membrane protein A (OmpA) in antimicrobial resistance remains unclear. This study aimed to evaluate the effect of OmpA expression on mycobacterial drug resistance. In this study, a Mycobacterium smegmatis (Ms) strain overexpressing OmpA (Ms-OmpA) and a Mycobacterium bovis (Mb) strain overexpressing OmpA (Mb-OmpA) were constructed, and their susceptibility to anti-TB drugs was determined by performing the minimal inhibitory concentrations (MICs), the plate assay and the macrophage infection assays. The streptomycin MIC of the overexpressing strain was 2-fold lower than those of the wide-type (Ms) and empty plasmid strains (pMV-261) as well as amikacin and gentamicin. Moreover, both the plate and the macrophage infection assays indicate that overexpression of OmpA increases streptomycin sensitivity in Mycobacteria. The other aminoglycosides like amikacin and gentamicin have the same phenotypes as streptomycin on the plates for the virulent strain Mb-OmpA. The porin inhibitor spermidine can increase streptomycin tolerance in the overexpressing strain, and overexpressing OmpA can increase the intracellular accumulation of hydrophilic ethidium bromide, which indicates that porin protein OmpA contributes to aminoglycosides sensitivity in Mycobacteria. In this study, we have characterized the contribution of OmpA in the antimicrobial resistance phenotype of Mycobacteria, which may provide valuable insights for understanding antibiotic resistance and designing new strategies for TB treatment.

Molecular docking and antibacterial and antibiotic-modifying activities of synthetic chalcone (2E)-1-(3'-aminophenyl)-3-(4-dimethylaminophenyl)-prop-2-en-1-one in a MepA efflux pump-expressing Staphylococcus aureus strain.

Bacterial resistance has become a global concern for public health agencies. Various resistance mechanisms found in Staphylococcus aureus strains grant this bacterium resistance to a wide range of antibiotics, contributing to the rise in human mortality worldwide. Resistance mediated by efflux pumps is one of the most prevalent mechanisms in multi-resistant bacteria, which has aroused the interest of several researchers in the search for possible efflux pump inhibitors. In view of the aforementioned considerations, it is important that new strategies, such as the synthesis of chalcones, be made available as a viable strategy in antimicrobial therapy. In this study, the synthesized chalcone (2E)-1-(3'-aminophenyl)-3-(4-dimethylaminophenyl)-prop-2-en-1-one was tested for its antibacterial activity, focusing on antibiotic modification and the inhibition of the MepA efflux pump present in S. aureus strain K2068. The broth microdilution method, using microdilution plates, was employed in microbiological tests to determine the minimum inhibitory concentration of the chalcone, antibiotics, and ethidium bromide. The results show that while the chalcone did not exhibit direct antibacterial activity, it synergistically enhanced the effects of ciprofloxacin and ethidium bromide, as evidenced by the reduction in MICs. In addition, computer simulations of molecular docking demonstrate that the tested chalcone acts on the same binding site as the efflux pump inhibitor chlorpromazine, interacting with essentially the same residues. These data suggest that the chalcone may act as a MepA inhibitor.

Preliminary Investigation of a Potential Optical Biosensor Using the Diamond™ Nucleic Acid Dye Applied to DNA and Friction Ridge Analysis from Fingerprint Traces

Developments in science and technology lead to an increasing use of scientific evidence in litigation. Interdisciplinary research can improve current procedures and introduce new ones for the disclosure and examination of evidence. The dactyloscopic trace is used for personal identification by matching minutiae (the minimum required may vary by country) or for extracting DNA material from the trace under investigation. The research presented in this article aims to propose the merging of two currently used personal identification methods, DNA analysis and dactyloscopic trace analysis, which are currently treated as separate forensic traces found at a crime scene. Namely, the forensic trace to be analyzed is the dactyloscopic trace containing DNA, and both sources of information needed for identification are examined as one. Promega’s Diamond™ Nucleic Acid Dye, presented as a safe alternative to ethidium bromide, works by binding to single- and double-stranded DNA and is used to visualize the separation of material in a gel and to detect DNA in forensic samples. Spectroscopic studies as absorption and emission spectra and fluorescence microscopy observations presented in our research confirm that Diamond™ Nucleic Acid Dye can also be used to visualize fingerprints on non-absorbent surfaces and that combining the two methods into one can significantly increase the evidential value and contribute to the design of an innovative fast-acting optical biosensor.

Coassembly of a Hybrid Synthetic-Biological Chitosan-g-Poly(N-isopropylacrylamide) Copolymer with DNAs of Different Lengths.

Natural polysaccharides can serve as carriers of genes owing to their intrinsic biocompatibility, biodegradability, and low toxicity. Additionally, they can be easily chemically modified, e.g., through grafting, leading to hybrid synthetic-biological copolymers with additional functionalities. In this work we report on the electrostatic interaction between a chitosan-g-poly(N-isopropylacrylamide) (Chit-g-PNIPAM) copolymer and DNA macromolecules of different lengths (i.e., 50 and 2000 bp), towards the construction of polyplexes that can serve as potential gene delivery systems. At the basic science level, the work aims to elucidate the effects of DNA length on the structural and physicochemical properties of the thermoresponsive hybrid macromolecular assemblies. The protonated amino groups on the chitosan backbone enable electrostatic binding with the anionic phosphate groups of the DNA molecules, while the PNIPAM side chains are expected to impart thermoresponsive properties to the formed polyplexes. Different amino to phosphate group (N/P) mixing ratios were examined, aiming to produce stable dispersions. The physicochemical properties of the resulting polyplexes were investigated by dynamic and electrophoretic light scattering (DLS and ELS), while their morphology was studied by scanning-transmission electron microscopy (STEM). Moreover, their response to changes in temperature and ionic strength, as well as their stability against biological media, was also examined. Finally, the binding affinity of the copolymer towards DNA was evaluated through fluorescence spectroscopy, using ethidium bromide quenching assays, while infrared spectroscopy was used to investigate the structure of the incorporated DNA chains.

The Intercalator Ethidium Bromide Generates Covalent Adducts at Apurinic/Apyrimidinic Sites in DNA.

Ethidium bromide was first described as a DNA intercalator 60 years ago and, over the ensuing years, may be the most widely used fluorescent DNA stain in molecular biology, biochemistry, and histology. Noncovalent DNA binding by ethidium has been well characterized, but to date, there have been no reports of covalent DNA adduct formation by ethidium bromide. This report describes the characterization of covalent adducts generated by the reaction of ethidium with apurinic/apyrimidinic (AP) sites in DNA. Adduct formation proceeds via the reaction of the amino group(s) on ethidium with the ring-opened aldehyde residue of the AP site in DNA to yield an imine. Ethidium-AP adducts may form under a variety of circumstances due to the ubiquitous occurrence of AP sites in cellular and synthetic DNA.

Enhanced Neuroprotection in Experiment Multiple Sclerosis through Combined Rosiglitazone and Probiotic-Loaded Solid Lipid Nanoparticles: Modulation of Cellular Signaling Pathways.

Multiple sclerosis (MS) is a persistent autoimmune condition characterized by inflammation and neurodegeneration. The current efficacy of treatments is limited, which has generated interest in developing neuroprotective strategies. Solid lipid nanoparticles (SLNs) and probiotics are potential drug delivery vehicles for targeting the CNS (Central nervous system), regulating immune responses, and supporting neuroprotection in neurological conditions. The study investigates how SLNs containing RSG (rosiglitazone) and probiotics can protect the nervous system in cases of MS. We administered toxin EtBr (Ethidium bromide) from day 1 to day 7, later followed by the treatment from day 8 to day 35. During this time interval, various behavioural parameters have been performed. Further, after 35th day, blood plasma of animals was collected to study complete CBC profiling and animals were sacrificed. Then, biochemical and molecular studies, gross morphology of brain sectioning, histopathological evaluation and estimation of fatty acid content in fecal matter were performed. RSG shows neuroprotective effects by blocking the STAT-3 and mTOR signaling pathways and increasing the production of PPAR-gamma. GW9662, a PPAR-gamma antagonist given at a dose of 2 mg/kg (i.p), was utilized to evaluate the role of PPAR-gamma and to compare the efficacy of RSG and probiotic-loaded SLNs in potentially providing neuroprotection. The relationship between RSG and the STAT-3, mTOR, and PPAR-gamma pathways in MS was confirmed and validated using in-silico analysis. RSG and probiotic-loaded SLNs modulate the complete blood profiling of rats and improve the symptoms of MS. We assessed the diagnostic capabilities of different biological samples such as cerebrospinal fluid, blood plasma, and brain homogenates (specifically from the hippocampus, striatum, cortex, and midbrain) to analyze neurochemical changes linked to neurobehavioral changes in the progression of MS. The study showed that combining RSG and probiotics in an experimental medication form improved symptoms of MS more effectively than using RSG alone. This improvement is likely due to changes in STAT-3, mTOR, and PPAR-gamma signaling pathways.

Liposomal formulation with thiazolic compounds against bacterial efflux pumps

This study aimed to evaluate the effects of liposome-encapsulated eugenol-based thiazolic derivatives against efflux pump-carrying bacteria. The Minimum Inhibitory Concentration (MIC) was determined to evaluate the antibacterial activity and antibiotic potentiation against Pseudomonas aeruginosa and Staphylococcus aureus, as well as to analyze the inhibition of efflux pumps in S. aureus strains 1199B and K2068 in the ethidium bromide assay. The direct antibacterial activity analysis showed no clinically relevant results since the compounds presented MICs ≥1024 µg/mL. Regarding the analysis of antibiotic potentiation against multidrug-resistant (MDR) strains of S. aureus, compound LF16 reduced norfloxacin MIC from 128 µg/mL to 64 µg/mL. All associated with gentamicin caused a significant antibiotic MIC reduction. None of the compounds could potentate the activity of norfloxacin against P. aeruginosa. However, all of them potentiated the activity of gentamicin against the same strain. Only the LF 26 caused a significant MIC reduction in the ethidium bromide assay, suggesting efflux inhibition in the S. aureus 1199B strain. Similar results were observed with the K2068 strain. Observing antibiotic MIC reduction S. aureus strains carrying the NorA and MepA proteins brought additional evidence of efflux pump inhibition. Our results indicate that while eugenol-based thiazoles didn’t exhibit direct activity, they can potentiate the antibiotics activity against MDR strains of P. aeruginosa and S. aureus. Among them, compound LF 26 potentiated the inhibitory effects of ethidium bromide and antibiotics against S. aureus strains carrying the NorA and MepA proteins, indicating a potential role of this class of compounds as efflux pump inhibitors.

A convenient approach for generating dimeric nucleic acid dyes via click-chemistry

Fluorescent dyes are essential tools for visualizing DNA and RNA. Dimeric dyes like GelGreen have gained popularity as safer alternatives to ethidium bromide (EB) due to their reduced mutagenicity and genotoxicity. In this study, we present a straightforward method to synthesize novel acridine orange (AO)-based dimeric dyes using click chemistry. Starting from acridine orange, these dyes can be synthesized in just two steps. Compared to GelGreen, these new dyes incorporate additional triazole groups in their linkers. They exhibit a maximum absorption wavelength of approximately 472 nm, which shifts to around 503 nm upon binding with DNA, allowing excitation by blue light. These dyes show minimal fluorescence in aqueous solutions, indicating that they adopt a closed conformation where the fluorescence of acridine orange is quenched due to intramolecular aggregation. The presence of DNA significantly enhances their fluorescence at around 526 nm, suggesting that DNA binding induces an open conformation. This “light-up” property makes them highly sensitive DNA dyes with a strong signal-to-noise ratio. We successfully applied these novel dyes in agarose gel electrophoresis, where they demonstrated excellent performance.

Structural, Antioxidant, and Protein/DNA-Binding Properties of Sulfate-Coordinated Ni(II) Complex with Pyridoxal-Semicarbazone (PLSC) Ligand

The pyridoxal-semicarbazone (PLSC) ligand and its transition metal complexes have shown significant biological activity. In this contribution, a novel nickel(II)-PLSC complex, [Ni(PLSC)(SO4)(H2O)2], was obtained, and its structure was determined by X-ray crystallographic analysis, FTIR, and UV-VIS spectroscopy. The sulfate ion is directly coordinated to the central metal ion. The intermolecular stabilization interactions were examined using Hirshfeld surface analysis. The crystal structure was optimized by a B3LYP functional using two pseudopotentials for nickel(II) (LanL2DZ and def2-TZVP) together with a 6-311++G(d,p) basis set for non-metallic atoms. The experimental and theoretical bond lengths and angles were compared, and the appropriate level of theory was determined. The stabilization interactions within the coordination sphere were investigated by the Quantum Theory of Atoms in Molecules (QTAIM). The antioxidant activity towards hydroxyl and ascorbyl radicals was measured by EPR spectroscopy. The interactions between Human Serum Albumin (HSA) and the complex were examined by spectrofluorimetric titration and a molecular docking study. The mechanism of binding to DNA was analyzed by complex fluorescence quenching, potassium iodide quenching, and ethidium bromide displacement studies in conjunction with molecular docking simulations.

New Pd(II)-pincer type complexes as potential antitumor drugs: synthesis, nucleophilic substitution reactions, DNA/HSA interaction, molecular docking study and cytotoxic activity.

Two new complexes of Pd(II), [Pd(L1)Cl]Cl (Pd1) and [Pd(L2)Cl]Cl (Pd2), (where L1 = N2,N6-bis(5-methylthiazol-2-yl)pyridine-2,6-dicarboxamide and L2 = N2,N6-di(benzo[d]thiazol-2-yl)pyridine-2.6-dicarboxamide) were synthesized. Characterization of the complexes was performed using elemental analysis, IR, 1H NMR spectroscopy and MALDI-TOF mass spectrometry. The nucleophilic substitution reactions of complexes with L-Methionine (L-Met), L-Cysteine (L-Cys) and guanosine-5'-monophosphate (5'-GMP) were studied by stopped-flow method at physiological conditions (pH = 7.2 and 37 °C). Complex Pd1 was more reactive than Pd2 in all studied reactions, while the order of reactivity of the selected ligands was: L-Met > L-Cys > 5'-GMP. The interaction of complexes with calf thymus-DNA (CT-DNA) was studied by Uv-Vis absorption and fluorescence emission spectroscopy. Competitive binding studies with intercalative agent ethidium bromide (EB) and minor groove binder Hoechst 33258 were performed as well. Both complexes interacted with DNA through intercalation and minor groove binding, where the latter was preferred. Additionally, the interaction of Pd1 and Pd2 complexes with human serum albumin (HSA) was studied employing fluorescence quenching spectroscopy. The results indicate a moderate binding affinity of complexes, with slightly stronger binding of the Pd1. Fluorescence competition experiments with site-markers (eosin Y and ibuprofen) for HSA were used to locate the binding site of Pd1 to the HSA. Additionally, the interaction with DNA and HSA was studied by molecular docking and the revealed results were in good agreement with the experimentally obtained ones. Pd1 complex exhibited cytotoxicity toward human (HCT116) and mouse cell lines (CT26) of colorectal cancer, mouse (4T1) and human (MDA-MB468) breast cancer lines and non-cancerous mouse mesenchymal stem cells (mMSC). In addition, Pd1 complex demonstrated significant selectivity towards cancer cells over non-cancerous mMSC, indicating a high potential to eliminate malignant cells without affecting normal cells. It induced apoptosis in CT26 cells, effectively arrested the cell cycle in the S phase, and selectively down-regulated cyclin D and cyclin E. Moreover, it can alter the expression of cell cycle regulators by increasing p21 and decreasing p-AKT. These findings confirm its ability to disrupt key tumor cell survival signals and suggest that the Pd1 complex is a potent candidate for effective cancer treatment.

Zwitterionic Nanochannels in Covalent Organic Framework Membranes for Improved Flux and Antifouling Property.

Zwitterionic membranes demonstrate excellent antifouling property in water purification. The covalent organic frameworks (COFs), due to the ordered channels and abundant organic functional groups, have distinct superiority in constructing zwitterionic surfaces.Here, the zwitterionic COF membrane is prepared with precise framework structures and uniform charge distribution. The negatively charged 4,4'-diaminobiphenyl-2,2'-sisulphonic acid sodium (SA) and positively charged ethidium bromide (EB) fragments are used to react with 1,3,5-triformylphloroglucinol (TP) at the gas-liquid interface to prepare zwitterionic COF membrane. The complementary charged fragments in the inter-layer and inner-layer facilitate the formation of continuous and tight hydration layer on the membrane surface and pore walls to resist the adsorption of pollutants. The zwitterionic COF membrane effectively resists both negatively charged bovine serum albumin and positively charged lysozyme pollutants with flux recovery ratio (FRR) of 97% and 85%, respectively. Furthermore, the regular nano-channels and balanced interactions between water and surface/pore walls of the zwitterionic membrane result in outstanding permeability of up to 146 L m-2 h-1 bar-1 and excellent dye/salt separation selectivity. The water permeation and antifouling mechanism of membranes are elucidated by experimental and molecular dynamics calculation. Zwitterionic COF membranes can find promising applications in preparing high-performance antifouling membranes.

In vitro and in silico effect of meldrum's acid-derived compounds on Staphylococcus aureus strains as NorA efflux pump inhibitors

The misuse of antibiotics has led to an alarming increase in bacterial strains resistant to these drugs. Efflux pumps, which expel antibiotics from bacterial cells, have emerged as one of the key mechanisms of bacterial resistance. In the quest to combat and mitigate bacterial resistance, researchers have turned their attention to efflux pump inhibitors as a potential solution. Meldrum's acid, a synthetic molecule widely utilized in the synthesis of bioactive compounds, has garnered significant interest in this regard. Hence, this study aims to investigate the antibacterial activity and evaluate the efficacy of three derivatives of meldrum's acid in inhibiting efflux mechanisms, employing both in silico and in vitro approaches. The antibacterial activity of the derivatives was assessed through rigorous broth microdilution testing. While the derivatives themselves did not exhibit direct antibacterial activity, they demonstrated remarkable potential in potentiating the effects of antibiotics. Additionally, fluorescence emission assays using ethidium bromide (EtBr) revealed fluorescence levels comparable to the positive control, indicating a possible blockade of efflux pumps. Molecular docking studies conducted in silico further supported these findings by revealing binding interactions similar to norfloxacin and CCCP, known efflux pump inhibitors. These results underscore the potential of meldrum's acid derivatives as effective inhibitors of efflux pumps. By inhibiting these mechanisms, the derivatives hold promise in enhancing the effectiveness of antibiotics and combatting bacterial resistance. This study contributes valuable insights into the development of novel strategies to address the pressing issue of bacterial resistance and paves the way for further research and exploration in this field.

Exploration of vanoxerine analogues as antibacterial agents.

Mycobacterium tuberculosis is a bacterial pathogen, responsible for approximately 1.3 million deaths in 2022 through tuberculosis infections. The complex treatment regimen required to treat tuberculosis and growing rates of drug resistance, necessitates the development of new anti-mycobacterial agents. One approach is to repurpose drugs from other clinical applications. Vanoxerine (GBR 12909) was previously shown to have anti-mycobacterial activity, through dissipating the membrane electric potential and hence, cellular energetics. Several vanoxerine analogues were synthesised in this study, which exhibited a range of activities against mycobacteria and enterococcus. All active analogues had similar impacts on the membrane electric potential and inhibition of ethidium bromide efflux. The most active compound displayed reduced inhibitory activity against the known human target of vanoxerine, the dopamine transporter. This work has identified a promising analogue, which could provide a starting point for further medicinal chemistry and drug development efforts to target mycobacteria.

Unwinding DNA strands by single-walled carbon nanotubes: Molecular docking and MD simulation approach

Despite the growing research into the use of carbon nano-tubes (CNTs) in science and medicine, concerns about their potential toxicity remain insufficiently studied. This study utilizes molecular docking calculations combined by molecular dynamics simulations to investigate the dynamic intricacies of the interaction between single-walled carbon nanotubes (swCNTs) and double-stranded DNA (dsDNA). By examining the influence of swCNT characteristics such as length, radius, and chirality, our findings shed light on the complex interplay that shapes the binding affinity and stability of the dsDNA-swCNT complex. Molecular docking results identify a zigzag swCNT, with a radius of 0.16 Å and a length of 38 Å, as exhibiting the highest binding affinity with dsDNA (−23.9 kcal/mol). Comprehensive analyses, spanning docking results, binding energies, RMSD, radius of gyration, and potential of mean force (PMF) profiles, provide a detailed understanding of the denaturation dynamics. The PMF profiles reveal the thermodynamic feasibility of the DNA-CNT interaction, outlining distinct energy landscapes and barriers: when the selected swCNT binds within the dsDNA groove, the system becomes trapped at the first and second local energy minima, occurring at 1.48 nm and 1.00 nm, respectively. Intramolecular hydrogen bond calculations show a significant reduction, affirming the denaturing effect of swCNTs on DNA. Furthermore, the study reveals a significant reduction in the binding affinity of Ethidium Bromide (EB) to dsDNA following its interaction with swCNT, with a decrease in EB binding to dsDNA of approximately 13.2 %. This research offers valuable insights into the toxic effects of swCNTs on dsDNA, contributing to a rationalization of the cancerous potential of swCNTs.

DNA interaction and cytotoxicity of a new asymmetric dimer cobalt(II) complex [Co(phen)2(Cl2)]3(H2O).[Co(phen)2(Cl)(H2O)](Cl)

The new, unusual and asymmetric cobalt(II) complex, [Co(phen)2(Cl2)]3(H2O).[Co(phen)2(Cl)(H2O)](Cl) (phen ​= ​1,10-phenanthroline), has been synthesized and characterized structurally by regular spectral and single crystal XRD analysis. An asymmetric complex crystallized in a monoclinic system with space group P21/c, a ​= ​14.093(5) Å, b ​= ​24.089(5) Å, c ​= ​14.241(5) Å, α ​= ​90.000(5)°, β ​= ​98.010(5)°, and γ ​= ​90.000(5)°. DNA binding interactions of complex with calf thymus DNA (CT-DNA) has investigated by UV–Vis absorption, ethidium bromide displacement assay, viscometric and cyclic voltammetric titrations, and the results infer an intercalation mode of binding. Complex cleaves effectively plasmid pBR322 DNA, and exhibits remarkable cytotoxic activity against human colon cancer cell line (HCT15).

Discovery of clinical isolation of drug-resistant Klebsiella pneumoniae with overexpression of OqxB efflux pump as the decisive drug resistance factor.

Background emergence of multidrug-resistant (MDR) bacterial strains is a public health concern that threatens global and regional security. Efflux pump-overexpressing MDR strains from clinical isolates are the best subjects for studying the mechanisms of MDR caused by bacterial efflux pumps. A Klebsiella pneumoniae strain overexpressing the OqxB-only efflux pump was screened from a clinical strain library to explore reverse OqxB-mediated bacterial resistance strategies. We identified non-repetitive clinical isolated K. pneumoniae strains using a matrix-assisted laser desorption/ionization time-of-flight (TOF) mass spectrometry clinical TOF-II (Clin-TOF-II) and susceptibility test screening against levofloxacin and ciprofloxacin. And the polymorphism analysis was conducted using pulsed-field gel electrophoresis. Efflux pump function of resistant strains is obtained by combined drug sensitivity test of phenylalanine-arginine beta-naphthylamide (PaβN, an efflux pump inhibitor) and detection with ethidium bromide as an indicator. The quantitative reverse transcription PCR was performed to assess whether the oqxB gene was overexpressed in K. pneumoniae isolates. Additional analyses assessed whether the oqxB gene was overexpressed in K. pneumoniae isolates and gene knockout and complementation strains were constructed. The binding mode of PaβN with OqxB was determined using molecular docking modeling. Among the clinical quinolone-resistant K. pneumoniae strains, one mediates resistance almost exclusively through the overexpression of the resistance-nodulation-division efflux pump, OqxB. Crystal structure of OqxB has been reported recently by N. Bharatham, P. Bhowmik, M. Aoki, U. Okada et al. (Nat Commun 12:5400, 2021, https://doi.org/10.1038/s41467-021-25679-0). The discovery of this strain will contribute to a better understanding of the role of the OqxB transporter in K. pneumoniae and builds on the foundation for addressing the threat posed by quinolone resistance.IMPORTANCEThe emergence of antimicrobial resistance is a growing and significant health concern, particularly in the context of K. pneumoniae infections. The upregulation of efflux pump systems is a key factor that contributes to this resistance. Our results indicated that the K. pneumoniae strain GN 172867 exhibited a higher oqxB gene expression compared to the reference strain ATCC 43816. Deletion of oqxB led a decrease in the minimum inhibitory concentration of levofloxacin. Complementation with oqxB rescued antibiotic resistance in the oqxB mutant strain. We demonstrated that the overexpression of the OqxB efflux pump plays an important role in quinolone resistance. The discovery of strain GN 172867 will contribute to a better understanding of the role of the OqxB transporter in K. pneumoniae and promotes further study of antimicrobial resistance.

2-Ferrocene-4-amine-1H-benzo[d]imidazole and their derivatives: Synthesis, biological and docking study

An organometallic series based on 2-ferrocene-4-amine-1H-benzo[d]imidazole derivative has been synthesized and characterized through FTIR, H/CNMR, and LCMS. Their antimicrobial activity was assessed by testing them against B. subtills, Staphylococcus aureus, E. faecalis, S. marcescens, E. coli, K. pneumoniae, C. albicans, A. niger, Mucor sp. where they showed good zone of inhibition (ZOI) as compared to standards. The cytotoxicity of synthesized compounds was tested against Hela (cervical) and MCF-7 (breast) cancer cell lines where compound 5a and 5b displayed equivalent potency to the standard while 5e demonstrated highest cytotoxicity against both cell lines. Their comparative docking analysis with DNA suggested that docking score of 5e was −7.4 kcal/mol versus −6 kcal/mol of ethidium bromide, indicating that our designed compound acts via DNA intercalation.

Efficient ethidium bromide removal using sodium alginate/graphene oxide composite beads: Insights into adsorption mechanisms and performance

This study explores the efficacy of sodium alginate/graphene oxide (SA/GO) composite beads for ethidium bromide (EtBr) removal from aqueous solutions. GO was synthesized and crosslinked with SA to design composite beads, which were evaluated under various physicochemical conditions. Characterization techniques, including FESEM, TGA, XRD, and FTIR, were employed to analyze the beads before and after EtBr adsorption. Results demonstrated rapid EtBr adsorption onto SA/GO, following the Freundlich isotherm model with a maximum adsorption capacity of 2.97mmol g−1 (1171.05 mg g−1). The influence of solution pH and the negligible role of Br− ions suggested that electrostatic interaction was the primary mechanism for EtBr adsorption on SA/GO. XRD and FTIR analyses revealed that EtBr adsorption also occurred in the interlayer space of SA/GO beads, with the ethidium cations (Et+) entering this space in a horizontal or oblique (≥45°) orientation. The accumulation of Et+ within the interlayer space was estimated to form 1–6 basic inclined layers. SA/GO beads demonstrated promising characteristics for EtBr pollutant treatment, including low environmental impact, cost-effectiveness, rapid adsorption kinetics, and high removal efficiency. This study provides valuable insights into the adsorption mechanisms and performance of SA/GO beads, highlighting their potential for future field applications in the environmental remediation of EtBr contamination.

Phytochemical profiling and anticancer potential of Cymbopogon citratus extract

Objective: To evaluate the anticancer potential of Cymbopogon citratus extract. Methods: GC-MS analysis was used to identify phytocomponents in the methanolic extract of Cymbopogon citratus. A fractionation method was employed to isolate and assess the bioactivity of different fractions and their cytotoxic activities against cancer cell lines HCT116, LoVo, Caco-2, and HT-29 were investigated. A dual staining method with acridine orange and ethidium bromide was used to assess the effect of the extract on cell apoptosis. Additionally, the expression levels of Bax and TP53 were quantified using realtime PCR in Caco-2 cells treated with the ethyl acetate fraction of Cymbopogon citratus extract. A protein array was employed to profile key pro- and anti-apoptotic proteins in Caco-2 cells. Moreover, molecular docking studies were conducted to investigate the interactions between key compounds of Cymbopogon citratus extract and specific apoptosis-related protein domains (PDB IDs: 7wql and 4bkx). Results: A significant growth inhibition was observed in Caco-2 cells treated with Cymbopogon citratus extract. Among the seven fractions of the plant extract, the ethyl acetate fraction showed the highest cytotoxicity against Caco-2 cells with an IC50 value of (6.16 ± 0.01) μg/mL. The immunofluorescence assay showed that the ethyl acetate fraction could induce apoptosis of Caco-2 cells. Moreover, the fraction upregulated the gene expressions of Bax and TP53 in a dose-dependent manner. The docking analysis demonstrated the interaction of five compounds isolated from the ethyl acetate fraction with key proteins in Caco-2 cells, indicating their anticancer properties. Conclusions: Cymbopogon citratus extract shows anticancer activity against Caco-2 cells by inducing apoptosis. It may be a promising candidate for the treatment of colon cancer, which needs further investigation.

Magnetic resonance metrics for identification of cuprizone-induced demyelination in the mouse model of neurodegeneration: a review.

Neurodegenerative disorders, including Multiple Sclerosis (MS), are heterogenous disorders which affect the myelin sheath of the central nervous system (CNS). Magnetic Resonance Imaging (MRI) provides a non-invasive method for studying, diagnosing, and monitoring disease progression. As an emerging research area, many studies have attempted to connect MR metrics to underlying pathophysiological presentations of heterogenous neurodegeneration. Most commonly, small animal models are used, including Experimental Autoimmune Encephalomyelitis (EAE), Theiler's Murine Encephalomyelitis (TMEV), and toxin models including cuprizone (CPZ), lysolecithin, and ethidium bromide (EtBr). A contrast and comparison of these models is presented, with focus on the cuprizone model, followed by a review of literature studying neurodegeneration using MRI and the cuprizone model. Conventional MRI methods including T1 Weighted (T1W) and T2 Weighted (T2W) Imaging are mentioned. Quantitative MRI methods which are sensitive to diffusion, magnetization transfer, susceptibility, relaxation, and chemical composition are discussed in relation to studying the CPZ model. Overall, additional studies are needed to improve both the sensitivity and specificity of MRI metrics for underlying pathophysiology of neurodegeneration and the relationships in attempts to clear the clinico-radiological paradox. We therefore propose a multiparametric approach for the investigation of MR metrics for underlying pathophysiology.