The interactions of metal ions with quinolone antibacterial agents

Safety analysis of quinolones use in minors-based on the FAERS database

Objective

This study utilizes the FDA Adverse Event Reporting System (FAERS) to investigate adverse drug event (ADE) signals linked to quinolones use (ciprofloxacin, moxifloxacin, levofloxacin, ofloxacin) in minors, offering insights for clinical use.

Methods

Minors were categorized into four age groups. ADE reports for these quinolones from the first quarter of 2015 to the third quarter of 2023 were extracted from the FAERS database. Data analysis used reporting odds ratio (ROR) and the MHRA method.

Results

Most ADE cases in minors involved ciprofloxacin (575)and levofloxacin (477). In the infant group, various injury, poisoning, and procedural complication events were more frequently associated with ciprofloxacin, levofloxacin, and moxifloxacin (19.83%, 31.25%, and 100.00%, respectively). In the preschool children group, psychiatric disorders were more frequently reported with levofloxacin and ofloxacin use (59.00% and 47.62%, respectively). Ocular disorders were notably associated with moxifloxacin in the children group (62.50%), In the adolescent group, more gastrointestinal diseases occurred with ciprofloxacin (12.96%).

Conclusion

ADE occurrence with quinolones in minors varies by age. Strict adherence to indications, rational use, avoiding prolonged use, and monitoring for short-term reactions are essential. Enhanced monitoring of interactions and drug education are crucial to reducing ADE.

Combined effects of cadmium and sulfamethoxazole on Eisenia fetida: Insights into accumulation, subcellular partitioning, biomarkers and toxicological responses

Cadmium (Cd) and sulfamethoxazole (SMX) frequently coexist in farmlands, yet their synergistic toxicological impacts on terrestrial invertebrates remain unexplored. In this study, earthworms were exposed to artificial soils percolated with Cd (5 mg/kg), SMX (5 mg/kg) or combination of them for 7 days, followed by a 12-day elimination phase in uncontaminated soil. The uptake of Cd and SMX by the earthworms, along with their subcellular distribution, was meticulously analyzed. Additionally, a suite of biomarkers-including superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and weight loss-were evaluated to assess the health status of the earthworms and the toxicological effects of the Cd and SMX mixture. Notably, the cotreatment with Cd and SMX resulted in a significantly higher weight loss in Eisenia fetida (41.25 %) compared to exposure to Cd alone (26.84 %). Moreover, the cotreatment group exhibited substantially higher concentrations of Cd in the total internal body, fraction C (cytosol), and fraction E (tissue fragments and cell membranes) in Eisenia fetida compared to Cd alone counterparts. The combined exposure also significantly elevated the SMX levels in the total body and fraction C compared with the SMX-only treated earthworms. Additionally, Eisenia fetida subjected to the combined treatment showed markedly increased activities of SOD, CAT, and MDA compared to those treated with Cd alone. The effect addition indices (EAIs), ranging from 1.00 to 2.23, unequivocally demonstrated a synergistic effect of the combined treatments. Interestingly, relocating the earthworms to clean soil did not mitigate the observed adverse effects. These findings underscore the increased risk posed by the Cd-SMX complex to terrestrial invertebrates in agricultural areas.

Attaching Metal-Containing Moieties to β-Lactam Antibiotics: The Case of Penicillin and Cephalosporin

Procedures for the preparation of transition metal complexes having intact bicyclic cepham or penam systems as ligands have been developed. Starting from readily available 4-azido-2-azetidinones, a synthetic approach has been tuned using a copper-catalyzed azide-alkyne cycloaddition between 3-azido-2-azetinones and alkynes, followed by methylation and transmetalation to Au(I) and Ir(III) complexes from the mesoionic carbene Ag(I) complexes. This methodology was applied to 6-azido penam and 7-azido cepham derivatives to build 6-(1,2,3-triazolyl)penam and 7-(1,2,3-triazolyl)cepham proligands, which upon methylation and metalation with Au(I) and Ir(III) complexes yielded products derived from the coordination of the metal to the penam C6 and cepham C7 positions, preserving intact the bicyclic structure of the penicillin and cephalosporin scaffolds. The crystal structure of complex 28b, which has an Ir atom directly bonded to the intact penicillin bicycle, was determined by X-ray diffraction. This is the first structural report of a penicillin-transition-metal complex having the bicyclic system of these antibiotics intact. The selectivity of the coordination processes was interpreted using DFT calculations.

Synthesis, Characterization and Evaluation of the Antimicrobial and Herbicidal Activities of Some Transition Metal Ions Complexes with the Tranexamic Acid

New tranexamic acid (TXA) complexes of ferric(III), cobalt(II), nickel(II), copper(II) and zirconium(IV) were synthesized and characterized by elemental analysis (CHN), conductimetric (Λ), magnetic susceptibility investigations (μeff), Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), ultraviolet visible (UV-vis.), optical band gap energy (Eg) and thermal studies (TG/DTG and DTA). TXA complexes were established in 1 : 2 (metal: ligand) stoichiometric ratio according to CHN data. Based on FT-IR and 1H-NMR data the disappeared of the carboxylic proton supported the deprotonating of TXA and linked to metal ions via the carboxylate group's oxygen atom as a bidentate ligand. UV-visible spectra and magnetic moment demonstrated that all chelates have geometric octahedral structures. Eg values indicated that our complexes are more electro conductive. DTA revealed presence of water molecules in inner and outer spheres of the complexes. DTA results showed that endothermic and exothermic peaks were identified in the degradation mechanisms. The ligand and metal complexes were investigated for their antimicrobial and herbicidal efficacy. The Co(II) and Ni(II) complexes showed antimicrobial activity against some tested species. The obtained results showed a promising herbicidal effect of TXA ligand and its metal complexes particularly copper and zirconium against the three tested plants.

Gyrase and Topoisomerase IV: Recycling Old Targets for New Antibacterials to Combat Fluoroquinolone Resistance

Beyond their requisite functions in many critical DNA processes, the bacterial type II topoisomerases, gyrase and topoisomerase IV, are the targets of fluoroquinolone antibacterials. These drugs act by stabilizing gyrase/topoisomerase IV-generated DNA strand breaks and by robbing the cell of the catalytic activities of these essential enzymes. Since their clinical approval in the mid-1980s, fluoroquinolones have been used to treat a broad spectrum of infectious diseases and are listed among the five "highest priority" critically important antimicrobial classes by the World Health Organization. Unfortunately, the widespread use of fluoroquinolones has been accompanied by a rise in target-mediated resistance caused by specific mutations in gyrase and topoisomerase IV, which has curtailed the medical efficacy of this drug class. As a result, efforts are underway to identify novel antibacterials that target the bacterial type II topoisomerases. Several new classes of gyrase/topoisomerase IV-targeted antibacterials have emerged, including novel bacterial topoisomerase inhibitors, Mycobacterium tuberculosis gyrase inhibitors, triazaacenaphthylenes, spiropyrimidinetriones, and thiophenes. Phase III clinical trials that utilized two members of these classes, gepotidacin (triazaacenaphthylene) and zoliflodacin (spiropyrimidinetrione), have been completed with positive outcomes, underscoring the potential of these compounds to become the first new classes of antibacterials introduced into the clinic in decades. Because gyrase and topoisomerase IV are validated targets for established and emerging antibacterials, this review will describe the catalytic mechanism and cellular activities of the bacterial type II topoisomerases, their interactions with fluoroquinolones, the mechanism of target-mediated fluoroquinolone resistance, and the actions of novel antibacterials against wild-type and fluoroquinolone-resistant gyrase and topoisomerase IV.

Removal of sulfamethoxazole and Cu, Cd compound pollution by arbuscular mycorrhizal fungi enhanced vertical flow constructed wetlands

The combined pollution of antibiotics and heavy metals (HMs) has a serious impact on the water ecological environment. Previous researches mainly focused on the removal of antibiotics or HMs as single pollutants, with limited investigation into the treatment efficiencies and underlying mechanisms associated with their co-occurring pollution. In this study, 16 micro vertical flow constructed wetlands (MVFCWs) were constructed to treat composite wastewater consisting of sulfamethoxazole (SMX), copper (Cu) and cadmium (Cd), involving two different inoculation treatments (arbuscular mycorrhizal fungi (AMF) inoculated and uninoculated) and eight kinds of pollutant exposure (Control Check (CK), SMX, Cu, Cd, SMX + Cu, SMX + Cd, Cu + Cd, SMX + Cu + Cd). The findings of this study demonstrated that the inoculation of AMF in MVFCWs resulted in removal efficiencies of SMX, Cu, and Cd ranging from 18.70% to 80.52%, 75.18% to 96.61%, and 40.50% to 89.23%, respectively. Cu and CuCd promoted the degradation of SMX in the early stage and inhibited the degradation of SMX in the later stage. Cd did not demonstrate a comparable promotive impact on SMX degradation, and its addition hindered Cu removal. However, comparatively, the presence of Cu exerted a more pronounced inhibitory effect on Cd removal. Furthermore, the addition of Cu augmented the abundances of Proteobacteria, Bacteroidetes (at the phylum level) and Rhodobacter, Lacunisphaera and Flavobacterium (at the genus level), and Cu exposure showed a substantially stronger influence on the microbial community than that of Cd and SMX. AMF might confer protection to plants against HMs and antibiotics by enriching Nakamurella and Lacunisphaera. These findings proved that AMF-C. indica MVFCW was a promising system, and the inoculation of AMF effectively enhanced the simultaneous removal of compound pollution.

Occurrence and source identification of antibiotics and antibiotic resistance genes in groundwater surrounding urban hospitals

Urban groundwater, serving as a critical reservoir for potable water, faces susceptibility to contamination from discrete sources such as hospital wastewater. This study investigates the distribution and plausible origins of antibiotics and antibiotic resistance genes (ARGs) in urban groundwater, drawing comparisons between areas proximal to hospitals and non-hospital areas. Ofloxacin and oxytetracycline emerged as the prevalent antibiotics across all samples, with a discernibly richer array of antibiotic types observed in groundwater sourced from hospital-adjacent regions. Employing a suite of multi-indicator tracers encompassing indicator drugs, Enterococci, ammonia, and Cl/Br mass ratio, discernible pollution from hospital or domestic sewage leakage was identified in specific wells, correlating with an escalating trajectory in antibiotic contamination. Redundancy analysis underscored temperature and dissolved organic carbon as principal environmental factors influencing antibiotics distribution in groundwater. Network analysis elucidated the facilitating role of mobile genetic elements, such as int1 and tnpA-02 in propagating ARGs. Furthermore, ARGs abundance exhibited positive correlations with temperature, pH and metallic constituents (e.g., Cu, Pb, Mn and Fe) (p < 0.05). Notably, no conspicuous correlation manifested between antibiotics and ARGs. These findings accentuate the imperative of recognizing the peril posed by antibiotic contamination in groundwater proximal to hospitals and advocate for the formulation of robust prevention and control strategies to mitigate the dissemination of antibiotics and ARGs.

Marbofloxacin combined with heavy rare-earth ions makes better candidates for veterinary drugs: crystal structure and bio-activity studies

Marbofloxacin (MB) is a newly developed fluoroquinolone antibiotic used especially as a veterinary drug. It may be regarded as the improved version of enrofloxacin owing to its antibacterial activity, enhanced bioavailability, and pharmacokinetic-pharmacodynamic (PK-PD) properties. In this study, nine heavy rare-earth ions (Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) were selected in light of their potential antibacterial activity and satisfactory biosafety to afford the corresponding rare-earth metal complexes of MB: the MB-Ln series. Their chemical structures and coordination patterns were characterized using IR spectroscopy, HRMS, TGA, and X-ray single-crystal diffraction analysis. Our results confirmed that all the MB-Ln complexes yielded the coincident coordination modes with four MB ligands coordinating to the Ln(III) center. In vitro antibacterial screening on five typical bacteria strains revealed that the MB-Ln complexes exhibited antibacterial activities comparable with MB, as indicated by the MIC/MBC values, in which Escherichia coli and Salmonella typhi were the most sensitive ones to MB-Ln. Furthermore, the MB-Ln complexes were found to be much less toxic in vivo than MB, as suggested by the evaluated LD50 (50% lethal dose) values. All the MB-Ln series complexes fell in the LD50 range of 5000-15 000 mg kg-1, while the LD50 value of MB was only 1294 mg kg-1. Furthermore, MB-Lu, as the selected representative of MB-Ln, could effectively inhibit the activity of DNA gyrase, the same as MB, suggesting the primary antibacterial mechanism of the MB-Ln series. The results demonstrated the good prospects and potential of metal-based veterinary drugs with better drug performance.

Refashioning of the drug-properties of fluoroquinolone through the synthesis of a levofloxacin-imidazole cobalt (II) complex and its interaction studies on with DNA and BSA biopolymers, antimicrobial and cytotoxic studies on breast cancer cell lines

Levofloxacin (HLVX), a quinolone antimicrobial agent, when deprotonated (LVX-) behaves as a bidentate ligand, and it coordinates to Co2+ through the pyridone oxygen and the carboxylate oxygen. Along with two imidazole (ImH) ligands, levofloxacin forms a Co(II)-Levofloxacin-imidazole complex, [CoCl(LVX)(ImH)2(H2O)]·3H2O (abbreviated henceforth as CoLevim) which was isolated and characterized by 1H and 13C NMR spectroscopy, UV-visible and FT-IR spectroscopy, powder X-ray diffraction and thermal analysis methods. CoLevim shows promise in its antimicrobial activities when tested against microorganisms (Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium and Escherichia coli). Fluorescence competitive studies with ethidium bromide (EB) revealed that CoLevim can compete with EB and displace it to bind to CT-DNA through intercalative binding mode. In addition, CoLevim exhibited a good binding propensity to BSA proteins with relatively high binding constants. The antioxidant activities of the free ligands and CoLevim were determined in vitro using ABTS+ radical (TEAC assay). The Co-complex showed a better antioxidant capacity with inhibitory concentrations (IC50) of 40 μM than the free ligands. CoLevim also showed noteworthy apoptotic potential and behaved as an efficient resistant modifying agent when its antiproliferative potential was examined by MTT assay using the breast cancer cell lines (MCF7, MCF7Dox/R and MCF7Pacli/R cells).

Aqueous chemistry of nalidixic acid and its complexes with biological relevant cations: A combination of potentiometric, UV spectrophotometric, MS and MS/MS study

Nalidixic acid (NAL) is a broad-spectrum antimicrobial widely used for urinary tract infections. As demonstrated, complexation of NAL with Zn2+, Mn2+ and Cu2+ was often used to get new formulations with an enhanced efficiency and potency. Therefore, the elucidation of behavior of NAL in solution and of its interaction with metal cations are crucial to better understand the influence of complexation on NAL efficiency and to find the optimal conditions to propose novel formulations. As a preliminary study, spectrophotometric titrations were carried out on NAL to determine the values of the protonation constants and to define its acid-base behavior. Then, the interaction with the three metal cations Zn2+, Mn2+ and Cu2+ was investigated by potentiometric and spectrophotometric titrations, varying the conditions of temperature, ionic strength and metal-ligand ratio, thus allowing to get the most robust speciation model and to determine the formation constants with Zn2+, Mn2+, and Cu2+ under different conditions, the sequestering ability of NAL towards metal cations, the formation enthalpic and entropic changes. A simulation under serum conditions was reported to show the relevance of the investigated species. Finally, LD-MS (laser desorption ionization mass spectrometry) and MS/MS analyses highlighted for all systems the formation of the complex species between Zn2+, Mn2+ and Cu2+ with NAL. MS/MS investigations assigned the sites of coordination of the ligand with the metal cation. More precisely, deprotonated NAL coordinates the metal cation via the oxygens of the carboxylate and the carbonyl groups.

Nalidixic Acid and Fe(II)/Cu(II) Coadsorption at Goethite and Akaganéite Surfaces

Interactions between aqueous Fe(II) and solid Fe(III) oxy(hydr)oxide surfaces play determining roles in the fate of organic contaminants in nature. In this study, the adsorption of nalidixic acid (NA), a representative redox-inactive quinolone antibiotic, on synthetic goethite (α-FeOOH) and akaganéite (β-FeOOH) was examined under varying conditions of pH and cation type and concentration, by means of adsorption experiments, attenuated total reflectance-Fourier transform infrared spectroscopy, surface complexation modeling (SCM), and powder X-ray diffraction. Batch adsorption experiments showed that Fe(II) had marginal effects on NA adsorption onto akaganéite but enhanced NA adsorption on goethite. This enhancement is attributed to the formation of goethite-Fe(II)-NA ternary complexes, without the need for heterogeneous Fe(II)-Fe(III) electron transfer at low Fe(II) loadings (2 Fe/nm2), as confirmed by SCM. However, higher Fe(II) loadings required a goethite-magnetite composite in the SCM to explain Fe(II)-driven recrystallization and its impact on NA binding. The use of a surface ternary complex by SCM was supported further in experiments involving Cu(II), a prevalent environmental metal incapable of transforming Fe(III) oxy(hydr)oxides, which was observed to enhance NA loadings on goethite. However, Cu(II)-NA aqueous complexation and potential Cu(OH)2 precipitates counteracted the formation of ternary surface complexes, leading to decreased NA loadings on akaganéite. These results have direct implications for the fate of organic contaminants, especially those at oxic-anoxic boundaries.

Modulating the transcriptomic profile of multidrug-resistant Klebsiella pneumoniae biofilm formation by antibiotics in combination with zinc sulfate

BACKGROUND

Klebsiella pneumoniae is a significant healthcare-associated pathogen. We investigated the antimicrobial interaction pattern between zinc sulfate and antibiotics against K. pneumoniae biofilm on the phenotypic and genotypic levels.

METHODS

Determining the minimum biofilm inhibitory concentrations and the transcriptomic profile of K. pneumoniae biofilm formation genes post-treatment were carried out to evaluate the effect on the phenotypic and genotypic levels, respectively.

RESULTS

Zinc enhanced the antibiofilm potentials of cephalosporins, aminoglycosides, and ertapenem, whereas it antagonizes the effectiveness of fluoroquinolones and meropenem on the phenotypic level. On the molecular level, zinc enhanced the anti-biofilm efficacies of cephalosporins (cefotaxime, ceftriaxone, ceftazidime, cefpirome, and cefepime) via down-regulating the expression of biofilm-related genes by 18-, 38-, 5-, 77- and 2-folds, respectively. Zinc in combination with aminoglycosides (kanamycin, gentamicin, and amikacin) reduced the expression of biofilm-related genes by 40-, 2602- and 20-folds, respectively, and by 2-folds in combination with ertapenem. However, a reduction in the down-regulatory potentials of fluoroquinolones was recorded following combination with zinc by 2-, 2-, 15- and 14-folds, respectively, and an up-regulation in the expression levels of the tested genes by 2-folds in the case of zinc/meropenem combination.

CONCLUSIONS

Results revealed variable interaction patterns between different antibiotics in combination with zinc. Current findings also shed light on the antibiofilm potentials of zinc/antibiotics combinations especially when combining zinc with fluoroquinolones or meropenem to avoid their antagonistic effects.

Repeated fluctuation of Cu2+ concentration during photocatalytic purification of SMZ-Cu2+ combined pollution: Behavior, mechanism and application

Although the effect of Cu²⁺ on antibiotic removal during photocatalytic reaction has been studied in depth, there is less known about the effect of antibiotics on Cu²⁺ removal. In this study, we report for the first time that, during the photocatalytic purification of sulfamerazine (SMZ) and Cu²⁺ combined pollution, Cu²⁺ concentration showed an obvious five-stage fluctuation, which was completely different from the simple promotion or inhibition reported in previous studies. By employing HPLC-MS analysis and density functional theory (DFT) calculation, the repeated fluctuation of Cu²⁺ concentration was found to be closely related to the SMZ degradation process, mainly resulting from solution pH drop and formation of Cu-containing intermediates which acted as sacrificial agents for Cu²⁺ reduction. In addition, compared with the SMZ-free system, the presence of SMZ can greatly enhance the deep removal of Cu²⁺ (minimum Cu²⁺ concentration was only 0.17 mg/L vs. 1.28 mg/L without SMZ), and there was a wide time interval to ensure the efficient recovery of Cu metal. More interestingly, the in-situ obtained Cu-decorated TiO₂ photocatalyst performed well in water splitting, nitrogen fixation and bacterial sterilization. Results of this study confirmed the great potential of photocatalytic technology in purifying antibiotic-heavy metal combined pollution.

Half-Sandwich Ruthenium Arene Complexes Bearing Clinically Approved Drugs as Ligands: The Importance of Metal-Drug Synergism in Metallodrug Design

A novel strategy in metallodrug discovery today is incorporating clinically approved drugs into metal complexes as coordinating ligands. Using this strategy, various drugs have been repurposed to prepare organometallic complexes to overcome the resistance of drugs and to design promising alternatives to currently available metal-based drugs. Notably, the combination of organoruthenium moiety and clinical drug in a single molecule has been shown, in some instances, to enhance pharmacological activity and reduce toxicity in comparison to the parent drug. Thus, for the past two decades, there has been increasing interest in exploiting metal-drug synergism to develop multifunctional organoruthenium drug candidates. Herein, we summarized the recent reports of rationally designed half-sandwich Ru(arene) complexes containing different FDA-approved drugs. This review also focuses on the mode of coordination of drugs, ligand-exchange kinetics, mechanism of action, and structure-activity relationship of organoruthenated complexes containing drugs. We hope this discussion may serve to shed light on future developments in ruthenium-based metallopharmaceuticals.

EEM-PARAFAC as a convenient methodology to study fluorescent emerging pollutants degradation: (fluoro)quinolones oxidation in different water matrices

Commercial (fluoro)quinolones ((F)Qs), ciprofloxacin (CIP), enrofloxacin (ENR), ofloxacin (OFL), oxolinic acid (OA) and flumequine (FLU) (3 μM each), were degraded with solar-photo-Fenton in a compound parabolic concentrator photoreactor (total volume 5 L) in ultra-pure water at pH = 5.0, salty water at pH = 5.0, and simulated wastewater at pH = 5.0 and 7.5. Iron speciation (its hydrolysis and the complexation with (F)Qs 15 μM and/or chlorides 0.5 M) was calculated at pH 5.0, observing, negligible formation of Fe(III)-chloride complexes, and that >99 % of the total (F)Qs are forming complexes stoichiometry 1:1 with Fe(III) (which also increases the percentage of Fe(OH)²⁺), being minoritarian the free antibiotic form. On the other hand, EEM-PARAFAC (fluorescence excitation-emission matrices-parallel factor analysis) was employed to simultaneously study the behaviour of: i) 4 structure-related groups corresponding to parent pollutants and slightly oxidised by-products, ENR-like (including CIP), OFL-like, OA-like, FLU-like; ii) intermediates still showing (F)Q characteristics (exhibiting analogous fluorescent fingerprint to ENR-like one, but shifted to shorter wavelengths); iii) humic-like substances. The scores from the 4 PARAFAC components corresponding to the parent pollutants were plotted vs. accumulated energy, exhibiting slower decay than their individual removals (measured with HPLC-UV/vis) due to the contribution of the aforementioned by-products to the overall fluorescence. Moreover, thiabendazole (TBZ) 3 μM was added as fluorescence interference. The presence of (F)Qs greatly enhanced TBZ degradation due to (F)Q-Fe(III) complex formation, keeping iron active at pH = 5.0 for Fenton process. The EEM-PARAFAC model was able to recognise the former six components plus an additional one attributable to TBZ-like.

Computational analysis, Urbach energy and Judd-Ofelt parameter of warm Sm3+ complexes having applications in photovoltaic and display devices

In this work, six reddish orange Sm3+ complexes were synthesized using organic ligand (L) and secondary ligands having hetero atoms by a one-step significant liquid-assisted grinding method and were characterized by spectroscopic techniques. The Urbach energy and band gap energy of the complexes were inspected by a linear fit. Using a least square fitting method, the Judd-Ofelt parameter and radiative properties were also determined. Thermal analysis, colorimetric analysis, luminescence decay time and anti-microbial properties of complexes were studied. The luminescence emission spectra of binary and ternary complexes displayed three characteristic peaks at 565, 603 and 650 nm in the powder form and four peaks at 563, 605, 646 and 703 nm in a solution phase due to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 transitions respectively. The most intense transition in the solid phase (4G5/2 → 6H7/2) is accountable for orange color, and in the solution form, the highly luminescent peak (4G5/2 → 6H9/2) is responsible for reddish orange color of Sm3+ complexes. PXRD and SEM analyses suggested that the complexes possess a nanoparticle grain size with crystalline nature. The decent optoelectrical properties of title complexes in the orangish-red visible domain indicated possible applications in the manufacturing of display and optoelectronic devices.

Synthesis of Mn-ofloxacin complex, experimental and in silico DNA binding evaluation, biological activity assessment

Metal-fluoroquinolones have more antibacterial and cytotoxic effects compared to free fluoroquinolones. In this work, a bidentated Mn (II) complex with ofloxacin (MOC) was synthesized and its cytotoxicity activity, oxidative stress and DNA binding were studied. Anti- proliferative and cytotoxic tests revealed that MOC exhibits better anti proliferative and cytotoxic activities compared to OFL which was attributed to the more interaction of MOC with DNA. Therefore, the interaction of MOC with DNA was investigated by using voltammetry, UV-Vis, fluorescence, and in silico methods. The results revealed that MOC interacts with DNA via electrostatic and outside hydrogen binding via minor groove. The proposed DNA binding modes may support the greater in-vitro cytotoxicity of MOC compared to OFL alone.

Gemifloxacin-transition metal complexes as therapeutic candidates: antimicrobial, antifungal, anti-enzymatic, and docking studies of newly synthesized complexes

In the era of acquired microbial resistance (AMR), resulting in the ineffectiveness of antibiotics is of keen interest for researchers in current scenarios. Ten novel metal complexes of gemifloxacin have been synthesized by reacting it with essential and trace elements in a 2:1 ratio predetermined conducto-metrically. As these metals are either present in the body or co-administered as metallic supplements can alter the level of antibiotics. Therefore, Metal complexes of Gemifloxacin, an important member of the fluoroquinolone family, were synthesized. The possible coordination of gemifloxacin with these metals has been proposed by the electronic and elemental data obtained through molar conductance, elemental analysis, and spectroscopic techniques like ultraviolet-visible (UV-Vis), infrared (IR), and proton-nuclear magnetic resonance (1H NMR) studies. In the light of these studies, the monoanionic bidentate ligand behavior of gemifloxacin in complexation with metals has been revealed. For in-vitro microbial studies, these newly synthesized complexes were tested against eleven different bacteria including Gram + ve and Gram -ve organisms, and one fungal strain. The results were compared with the parent drug by applying ANOVA through SPSS software version 22. Therefore, it has been found that among all synthesized metal complexes, the G-M01 complex exhibits increased activity against B. subtilis, P. mirabilis, E. coli, K. pneumonia, and C. freundii. Complex G-M02, G-M03, G-M04, and G-M10 show more pronounced activity than Gemifloxacin against S. aureus and M. luteus. Moreover, the binding orientations of the synthesized metal complexes into the binding site of the urease enzyme revealed that all the docked metal complexes oriented away from the Ni bi-center, and the inactivation of urease is due to their interaction with entrance flap residues.

Spectroscopic Analyses and Antimicrobial Activity of Novel Ciprofloxacin and 7-Hydroxy-4-methylcoumarin, the Plant-Based Natural Benzopyrone Derivative

Coumarin is highly distributed in nature, notably in higher plants. The biological features of coumarin include antibacterial, anticancer and antioxidant effects. It is well known that metal ions present in complexes accelerate the drug action and the efficacy of organic therapeutic agents. The main aim of the current study is the synthesis of different complexes of the interaction between ciprofloxacin hydrochloride (CIP) and coumarin derivative 7-hydroxy-4-methylcoumarin (HMC) with Zr(IV). The chelates of CIP with Zr(IV) were prepared and characterized by elemental analysis, melting point, conductance measurements, spectroscopic techniques involving IR, UV-Vis, ¹H NMR, and thermal behavior (TG-DTG) in the presence of HMC, dimethylformamide (DMF), pyridine (Py), and triethylamine (Et₃N). Results of molar conductivity tests showed that the new synthesized complexes are electrolytes with a 1:1 or 1:2 electrolyte ratio, with the chloride ions functioning as counter ions. According to IR spectra, CIP acts as a neutral bidentate ligand with Zr(IV) through one carboxylato oxygen and the carbonyl group, HMC as a monodentate through the carbonyl group, and DMF through the oxygen atom of the carbonyl group and the N atom of Py and Et₃N. The thermal behavior of the complexes was carefully investigated using TG and DTG techniques. TG findings signal that water molecules are found as hydrated and coordinated. The thermal decomposition mechanisms proposed for CIP, HMC, and Zr(IV) complexes are discussed and the activation energies (E_a), Gibbs free energies (∆G*), entropies (∆S*), and enthalpies (∆H*) of thermal decomposition reactions have been calculated using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The studied complexes were tested against some human pathogens and phytopathogens, including three Gram-positive bacteria (Bacillus subtilis, B. cereus, Brevibacterium otitidis) and three Gram-negative bacteria (Escherichiacoli, Pseudomonas aeruginosa and Klebsiella pneumoniae), and compared to the free CIP and HMC parent compounds.

Molecular structures of two copper complexes with the pharmaceuticals norfloxacin and tinidazole, when powder X-ray diffraction assists multi-domain single-crystal X-ray diffraction

The crystal structures of bis[1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-ium-4-yl)-1,4-dihydroquinoline-3-carboxylato]copper(II) sulfate heptahydrate, [Cu(C₁₆H₁₈FN₃O₃)₂]SO₄·7H₂O or [Cu(nor)₂]SO₄·7H₂O (nor is norfloxacin), and bis{1-[2-(ethylsulfonyl)ethyl]-2-methyl-5-nitroimide}dinitratocopper(II), [Cu(NO₃)₂(C₈H₁₃N₃O₄S)₂] or [Cu(NO₃)₂(tnz)₂] (tnz is tinidazole), were solved by X-ray diffraction. Both complexes crystallize in the space group P2₁/c, with Z = 4 (for nor) and Z = 2 (for ntz) molecules per unit cell. In [Cu(nor)₂]SO₄·7H₂O, the Cu^II ion is at the centre of a square-planar environment, trans coordinated to two independent norfloxacin molecules in the zwitterionic form acting as bidentate ligands through one of the carboxyl (cbx) and the carbonyl (cb) O atoms. The solid is further stabilized by an extensive network of N-H...O(sulfate), N-H...O(cbx), N-H...OW, OW-H...O(sulfate) and OW-H...OW hydrogen bonds. The [Cu(NO₃)₂(tnz)₂] complex is centrosymmetric, with the Cu^II ion in a square planar environment, coordinated to a tinidazole molecule acting as a monodentate ligand through its imidazole N atom and to one nitrate O atom. The vibrational FT-IR absorption spectra and thermal behaviour of the complexes were also studied and are briefly discussed based on the crystal structures.

Metal(II) Complexes of the Fluoroquinolone Fleroxacin: Synthesis, Characterization and Biological Profile

A series of complexes of divalent transition metals (Cu(II), Mn(II), Zn(II), Co(II) and Ni(II)) with the quinolone antibacterial agent fleroxacin, in the absence or presence of an α-diimine such as 2,2′-bipyridine, 1,10-phenanthroline or 2,2′-bipyridylamine, were prepared and characterized. The complexes were characterized by various physicochemical and spectroscopic techniques and by single-crystal X-ray crystallography. The in vitro antibacterial activity of the complexes was studied against the bacterial strains Staphylococcus aureus, Bacillus subtilis and Xanthomonas campestris and was higher than that of free quinolone. The affinity of the complexes for bovine and human serum albumin was studied by fluorescence emission spectroscopy and the determined binding constants showed tight and reversible binding to the albumins. The interaction of the complexes with calf-thymus DNA was studied by various techniques, which showed that intercalation was the most plausible mode of interaction.

Dynamic changes in the intestinal microbial community of two time-aged soils under combined cadmium and ciprofloxacin contaminated conditions

The effects of combined contaminated soils containing cadmium (Cd) and ciprofloxacin (CIP) on the human gut microbiota are demonstrated using an in vitro test. Uncontaminated soil samples were artificially polluted with Cd and CIP using three different treatments (CK: 0 mg·kg^-1; CIPI: 5 mg·kg^-1, CIPII: 25 mg·kg^-1, and Cd: 80 mg·kg^-1). An experiment was performed to investigate the effect of Cd and CIP on the human colon microbiota using two aging times (D30: Day 30; D60: Day 60), and then the method of high-throughput 16S rRNA gene sequencing was used. In this study, we observed five phyla: Proteobacteria, Firmicutes, Synergistetes, Bacteroidetes, and Actinobacteria in colon microbial community. In addition, our results indicated that the relative abundances of the gut bacteria varied at the phylum level. Nevertheless, a slight decline in the relative abundance of Bacteroidetes among all the sets (compared to the D30-CK + Cd set) was revealed, and the lowest decline percentage of 90% was observed in the D60-CIPI + Cd set. Our results validated that the relative abundance of Rhodococcus increased with an increase in the CIP concentration in D30. In addition, this may disrupt normal physiological functions of the intestine after exposure to contaminated soil via the mouth. This study provides a theoretical basis for human risk assessment of oral exposure to Cd and CIP contaminated soils.

Estimating combined health risks of nanomaterials and antibiotics from natural water: a proposed framework

Nanoparticles (NPs) are one of the major class of emerging contaminants identified in aquatic environment. There is a probability that they can co-exist with other chemical pollutants like antibiotics (ABs) as ABs-NPs complexes in natural water systems. If these complexes are taken up via inadvertent ingestion of contaminated water, it might show detrimental effects on human health. To address this challenging issue, this study developed a risk framework to assess the combined exposure of ABs and NPs in natural waters for the first time. The six-step framework was applied to a hypothetical exposure of NPs (copper oxide, CuO; zinc oxide, ZnO; iron oxide, Fe₃O₄; and titanium oxide, TiO₂) and ABs (ciprofloxacin, CIP; ofloxacin, OFX; norfloxacin, NOR; and levofloxacin, LEVO) to estimate human health risks for two different exposure scenarios. Risk estimation was also conducted for the released fragments of ABs, NPs and metal ions in the human digestive system. Mixture toxicity risk assessment was conducted for three different combinations: (i) ABs and metal ions, (ii) ABs and NPs, and (iii) NPs and metals ions. Although the expected risk values were observed to be less than 1 (both hazard quotients and hazard interactions less than 1) for all the conditions and assumptions made, still a thorough monitoring and analysis of the studied contaminants in water is required to protect humans from their adverse effects, if any. Maximum allowable concentrations (C_max) at which no risk can occur to humans was found to be (maximum values): ABs (233.8 µg/L, NOR); metal ions (1.02 × 10⁹ mg/L, Ti²⁺ ions), and NPs (6.68 × 10⁵ mg/L, TiO₂), respectively.

A New Calcium(II)-Based Substitute for Enrofloxacin with Improved Medicinal Potential

Enrofloxacin (EFX) reacting with Ca(II) afforded a new complex, [Ca(EFX)₂(H₂O)₄] (EFX-Ca), which was structurally characterized both in solid and solution chemistry. E. coli and S. typhi were tested to be the most sensitive strains for EFX-Ca. The LD₅₀ value of EFX-Ca in mice was 7736 mg/kg, implying the coordination of EFX to Ca(II) effectively reduced its acute toxicity. EFX-Ca also decreased the plasma-binding rate and enhanced the drug distribution in rats along with longer elimination half-life. EFX-Ca also showed similar low in vivo acute toxicity and higher anti-inflammation induced by H₂O₂ or CuSO₄ in zebrafish, with reactive oxygen species (ROS)-related elimination. The therapeutic effects of EFX-Ca on two types (AA and 817) of E. coli-infected broilers were also better than those of EFX, with cure rates of 78% and 88%, respectively. EFX-Ca showed promise as a bio-safe metal-based veterinary drug with good efficacy and lower toxicity.

Experimental and modeling studies of competitive Pb (II) and Cd (II) bioaccumulation by Aspergillus niger

Co-existence of toxic metals causes complex toxicity to microorganisms during bioremediation in water and soil. This study investigated the immobilization of Pb²⁺ and Cd²⁺ by fungus Aspergillus niger, which has been widely applied to environmental remediation. Five treatments were set, i.e., CK (no toxic metals), Pb²⁺ only, Cd²⁺ only, Pb²⁺/Cd²⁺ = 1:1(molar ratio), and Pb²⁺/Cd²⁺ = 2:1. Cadmium induced strong toxicity to the fungus, and maintained the high toxicity during incubation. However, as Pb/Cd ratio increased from 0 to 2, the removal rates of Cd²⁺ by A. niger were raised from 30 to 50%. The elevated activities of pyruvate dehydrogenase (PDH) and citrate synthetase (CS) enzymes confirmed that Pb addition could stimulate the growth of A. niger. For instance, citric acid concentrations and CS activities were 463.22 mg/L and 78.37 nmol/min/g, respectively, during 3-day incubation as Pb/Cd = 1. However, these two values were as low as ~ 50 with addition of only Cd. It was hence assumed that appropriate co-existence of Pb²⁺ enhanced microbial activity by promoting TCA cycle of the fungus. Moreover, the SEM analysis and geochemical modeling demonstrated that Pb²⁺ cations were more easily adsorbed and mineralized on A. niger with respect to Cd²⁺. Therefore, instead of intensifying metal toxicity, the addition of appropriate Pb actually weakened Cd toxicity to the fungus. This study sheds a bright future on application of A. niger to the remediation of polluted water with co-existence of Pb and Cd. KEY POINTS: • Cd²⁺ significantly inhibited P consumption, suggesting its high toxicity to A. niger. • Pb²⁺ stimulated the growth of A. niger by promoting TCA cycle in the cells. • Cd²⁺ removal by A. niger were improved with co-existence of Pb²⁺.

Fluoroquinolone-Transition Metal Complexes: A Strategy to Overcome Bacterial Resistance

Fluoroquinolones (FQs) are antibiotics widely used in the clinical practice due to their large spectrum of action against Gram-negative and some Gram-positive bacteria. Nevertheless, the misuse and overuse of these antibiotics has triggered the development of bacterial resistance mechanisms. One of the strategies to circumvent this problem is the complexation of FQs with transition metal ions, known as metalloantibiotics, which can promote different activity and enhanced pharmacological behaviour. Here, we discuss the stability of FQ metalloantibiotics and their possible translocation pathways. The main goal of the present review is to frame the present knowledge on the conjunction of biophysical and biological tools that can help to unravel the antibacterial action of FQ metalloantibiotics. An additional goal is to shed light on the studies that must be accomplished to ensure stability and viability of such metalloantibiotics. Potentiometric, spectroscopic, microscopic, microbiological, and computational techniques are surveyed. Stability and partition constants, interaction with membrane porins and elucidation of their role in the influx, determination of the antimicrobial activity against multidrug-resistant (MDR) clinical isolates, elucidation of the mechanism of action, and toxicity assays are described for FQ metalloantibiotics.

Effects of Magnesium, Calcium, and Aluminum Chelation on Fluoroquinolone Absorption Rate and Bioavailability: A Computational Study

Fluoroquinolones (FQs) are a widespread class of broad-spectrum antibiotics prescribed as a first line of defense, and, in some cases, as the only treatment against bacterial infection. However, when administered orally, reduced absorption and bioavailability can occur due to chelation in the gastrointestinal tract (GIT) with multivalent metal cations acquired from diet, coadministered compounds (sucralfate, didanosine), or drug formulation. Predicting the extent to which this interaction reduces in vivo antibiotic absorption and systemic exposure remains desirable yet challenging. In this study, we focus on quinolone interactions with magnesium, calcium and aluminum as found in dietary supplements, antacids (Maalox) orally administered therapies (sucralfate, didanosine). The effect of FQ-metal complexation on absorption rate was investigated through a combined molecular and pharmacokinetic (PK) modeling study. Quantum mechanical calculations elucidated FQ-metal binding energies, which were leveraged to predict the magnitude of reduced bioavailability via a quantitative structure-property relationship (QSPR). This work will help inform clinical FQ formulation design, alert to possible dietary effects, and shed light on drug-drug interactions resulting from coadministration at an earlier stage in the drug development pipeline.

Quantitative characterization of toxicity interaction within antibiotic-heavy metal mixtures on Chlorella pyrenoidosa by a novel area-concentration ratio method

Toxicity interaction, synergism and antagonism, may occur when multiple pollutants are exposed to the environment simultaneously, which limits the utility of some standard models to assess toxicity hazards and risks. The development and application of models which can provide an insight into the combined toxicity of pollutants becomes necessary. Therefore, a novel model, area-concentration ratio (ACR) method, was developed to characterize the toxicity interaction within mixtures of three aminoglycoside antibiotics (AGs), kanamycin sulfate (KAN), paromomycin sulfate (PAR), tobramycin (TOB) and one heavy metal copper (Cu) in this study. The inhibition toxicity of single contaminants and mixtures designed by direct equilibration ray method and uniform design ray method to Chlorella pyrenoidosa (C. pyrenoidosa) was determined by the microplate toxicity analysis (MTA). The results showed that the novel method ACR could be used for quantitative characterization of combined toxicity. According to the ACR, all the binary AG antibiotic mixture systems display obvious synergism and weak antagonism. The addition of the heavy metal Cu into binary AG antibiotic mixtures can obviously change toxicity interaction, but toxicity interaction changing trend varies greatly in different ternary mixture systems. Toxicity interaction in the six mixture systems has component concentration-ratio dependence. ACR can be suggested as an effective novel method to quantitatively characterize toxicity interaction when assessing the hazards and risks of the combined pollution.

Passive Diffusion of Ciprofloxacin and its Metalloantibiotic: A Computational and Experimental study

Fluoroquinolones (FQ) are antibiotics widely used in clinical practise, but the development of bacterial resistance to these drugs is currently a critical public health problem. In this context, ternary copper complexes of FQ (CuFQPhen) have been studied as a potential alternative. In this study, we compared the passive diffusion across the lipid bilayer of one of the most used FQ, ciprofloxacin (Cpx), and its ternary copper complex, CuCpxPhen, that has shown previous promising results regarding antibacterial activity and membrane partition. A combination of spectroscopic studies and molecular dynamics simulations were used and two different model membranes tested: one composed of anionic phospholipids, and the other composed of zwitterionic phospholipids. The obtained results showed a significantly higher membrane permeabilization activity, larger partition, and a more favourable free energy landscape for the permeation of CuCpxPhen across the membrane, when compared to Cpx. Furthermore, the computational results indicated a more favourable translocation of CuCpxPhen across the anionic membrane, when compared to the zwitterionic one, suggesting a higher specificity towards the former. These findings are important to decipher the influx mechanism of CuFQPhen in bacterial cells, which is crucial for the ultimate use of CuFQPhen complexes as an alternative to FQ to tackle multidrug-resistant bacteria.

Role of Metal-Chloride Anions in Photoluminescence Regulations for Hybrid Metal Halides

Organic-inorganic hybrid metal halides with emissive organic cations are of great interest due to their structural diversity and interesting photophysical properties. Here, we assemble emissive organic cations (EnrofloH₂²⁺) with different metal-chloride anions (Pb₂Cl₆^2- to Bi₂Cl₁₀^4- to SnCl₆^2-) to form the new single crystal phases, and thus the photoluminescence properties of the metal halides, including Stokes shift, full width at half-maximum (FWHM), and photoluminescence quantum yield (PLQY) have been studied accordingly. (EnrofloH₂)SnCl₆·H₂O, as an example, possesses narrow FWHM and high PLQY, which are caused by the strong π-π stacking and inter- and intramolecular hydrogen bonds interactions. Compared with EnrofloH₂²⁺ cation in solution, the interactions generate a restraining effect and increase the rigid degree of EnrofloH₂²⁺ cation in the bulk single crystals. Our work clarifies the photophysical properties of the EnrofloH₂²⁺ organic cations by constructing the inter- and intramolecular interactions and boosts the further study of organic-inorganic hybrid metal halides materials with different luminescence mechanisms.

Antioxidant vs. Prooxidant Properties of the Flavonoid, Kaempferol, in the Presence of Cu(II) Ions: A ROS-Scavenging Activity, Fenton Reaction and DNA Damage Study

Kaempferol is a flavonoid that occurs in tea and in many vegetables and fruits, including broccoli, cabbage, beans, grapes, apples, and strawberries. The efficacy of Kaempferol has been demonstrated in the treatment of breast, esophageal, cervical, ovarian, and liver cancers and leukemia, which very likely arises from its prooxidant properties and the activation of pro-apoptotic pathways. Indeed, this matter has already been the focus of a number of published studies and reviews. The aim of the present study was to elucidate the antioxidant vs. prooxidant properties of flavonoids in the presence of the redox-active metal, copper (II) ion, by means of the Fenton reaction. The specific motivation of this work is that, since an increased level of Cu(II) ions is known to be associated with many disease states such as neurological conditions (Alzheimer’s disease) and cancer, any interaction between these ions and flavonoids might affect the outcome of therapeutic uses of the latter. The structure of the Cu-kaempferol complex in DMSO was investigated by means of low temperature EPR spectroscopy, which confirmed the existence of at least two distinct coordination environments around the copper (II) ion. UV vis-spectra of kaempferol and its Cu(II) complex in DMSO revealed an interaction between the 5-OH (A ring) group and the 4-CO (C ring) group of kaempferol with Cu(II) ions. An ABTS assay confirmed that kaempferol acted as an effective radical scavenger, and that this effect was further enhanced in the form of the Cu(II)-kaempferol complex. Quantitative EPR spin trapping experiments, using DMPO as the spin trap, confirmed suppression of the formation of a mixture of hydroxyl, superoxide, and methyl radicals, in a Fenton reaction system, upon coordination of kaempferol to the redox-active Cu(II) ions, by 80% with respect to the free Cu(II) ions. A viscometric study revealed a better DNA-intercalating ability of the Cu-kaempferol complex than for free kaempferol, essential for conferring anticancer activity of these substances. The results of the viscometric measurements were compared with those from a DNA damage study of Cu-kaempferol complexes in a Fenton reaction system, using gel electrophoresis. At low concentrations of kaempferol (Cu–kaempferol ratios of 1:1 and 1:2), a very weak protective effect on DNA was noted, whereas when kaempferol was present in excess, a significant DNA-protective effect was found. This can be explained if the weakly intercalated kaempferol molecules present at the surface of DNA provide protection against attack by ROS that originate from the Fenton reaction involving intercalated Cu(II)-kaempferol complexes. Following the application of ROS scavengers, L-histidine, DMSO, and SOD, gel electrophoresis confirmed the formation of singlet oxygen, hydroxyl radicals, and superoxide radical anions, respectively. We propose that the prooxidant properties of Cu-kaempferol complexes may provide anticancer activity of these substances. When present in excess, kaempferol displays antioxidant properties under Cu-Fenton conditions. This suggests that kaempferol might prove a suitable candidate for the prevention or treatment of oxidative stress related medical conditions that involve a disturbed metabolism of redox metals such as copper, for example, Menkes disease, and neurological disorders, including Alzheimer’s disease. For the potential use of kaempferol in clinical practice, it will be necessary to optimize the dose size and critical age of the patient so that this flavonoid may be beneficial as a preventive drug against cancer and neurological disorders.