Synthesis of sulfamethoxazole and sulfabenzamide metal complexes; evaluation of their antibacterial activity

Advances in isoxazole chemistry and their role in drug discovery

Isoxazoles are a class of five-membered heterocyclic compounds that have gained significant attention in medicinal chemistry due to their diverse biological activities and therapeutic potential. Recent advances in isoxazole chemistry have led to the development of novel synthetic strategies, enabling the creation of a wide array of isoxazole derivatives with enhanced bioactivity and selectivity. This review explores the latest progress in isoxazole synthesis, highlighting key methodologies such as transition metal-catalyzed cycloadditions, green chemistry approaches, and regioselective functionalization techniques. These advances have not only improved the efficiency of isoxazole synthesis but have also facilitated the design of more complex and bioactive derivatives. In addition to their synthetic advances, isoxazoles have demonstrated a broad spectrum of biological activities, including antimicrobial, anticancer, anti-inflammatory, and neuroprotective effects, making them attractive candidates in drug discovery. This review discusses the structural modifications that enhance their pharmacological properties and their potential for developing therapies for diseases such as cancer, neurodegenerative disorders, and infections. Moreover, we examine the emerging trends in isoxazole-based drug discovery, such as the development of multi-targeted therapies and personalized medicine approaches. The evolving role of isoxazoles in drug discovery underscores their continued importance in modern pharmaceutical research and their potential to address unmet medical needs.

Aquifer pollution by metal-antibiotic complexes: Origins, transport dynamics, and ecological impacts

Aquifer pollution by metal-antibiotic complexes is a rising environmental and public health concern owing to their enhanced mobility and persistence in groundwater. The purpose of this review is to examine the origins, transport dynamics, and ecological impacts of complexes formed through interactions between metal ions and antibiotics in agricultural runoff, pharmaceutical effluents, and wastewater discharge. Metal-antibiotic complexes are more resistant to degradation and are more soluble than their components. This complicates the conventional water purification efforts. These complexes disrupt microbial ecosystems, facilitate the spread of antibiotic-resistance genes, and negatively affect aquatic organisms. The entry of pollutants into drinking water sources poses notable health risks, including chronic exposure to contaminants and the emergence of antibiotic-resistant pathogens. This review emphasizes both preventative and remedial strategies to mitigate these impacts. Preventative measures emphasize the regulation of antibiotic and metal use in agriculture and industry and promote green chemistry alternatives. Remediation approaches include advanced treatment technologies such as membrane filtration, oxidation, and bioremediation. Integrated management practices and ongoing monitoring were discussed to address this complex issue. To protect water quality and public health, metal-antibiotic complexes in aquifers require stringent regulatory measures, innovative treatment solutions, and heightened public awareness. This review highlights the importance of coordinated efforts to prevent and remediate the emerging pollution problem.

A novel strategy to bind pyrimidine sulfonamide derivatives with odd even chains: exploration of their design, synthesis and biological activity evaluation

Based on the hybridization strategy of dominant fragments, a series of pyrimidine sulfonamide (PS) derivatives were obtained by combining the pharmacophore fragments (sulfonamide group and pyrimidine group) with different biological activities, and evaluated as a new type of anticancer drug. The compounds were evaluated for in vitro cytotoxicity against four human cancer cell lines (HeLa, HCT-116, A-549 and HepG2) and the normal human cell line L02. Compared with the anti-cancer drug 5-fluorouracil (5-FU), the antiproliferative activity of compound PS14 was close to 5-FU and it has good antitumor activity. The IC50 values were 15.13 ± 2.20, 19.87 ± 2.01, 12.64 ± 3.22, 22.20 ± 1.34 and 102.46 ± 2.27 μM, respectively. The structure activity relationship was analyzed. The antitumor activity of the compound tended to increase. When the substituents of the branch chain of sulfonamides were odd. In addition, the oil-water partition coefficient was also investigated. The logP value of PS14 was between 0 and 3, indicating that PS14 was a compound with good lipophilic property, poor water solubility and easy to be absorbed and transported through cell membrane. The anti-cancer mechanism was further studied by flow cytometry. After PS14 treated HeLa, HCT-116, A-549 and HepG2, the percentage of apoptotic cells was 45.30%, 28.2%, 31.00% and 35.20%, respectively, which was higher than that of the control 5-FU. The results of cell cycle showed that PRD2 mainly blocked the cell cycle in the S phase, thereby inhibiting cell proliferation. Furthermore, molecular docking analyzed possible interactions between the compound and the PI3Kα active site, this compound has good binding with PI3Kα. Overall, this study laid the groundwork for the development and structural modification of new pyrimidine sulfonamide drugs, and PS14 could be further developed into a cancer treatment drug.

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.

Synthesis of novel sulphamethoxazole derivatives and exploration of their anticancer and antimicrobial properties

A series of new derivatives based on sulfamethoxazole were designed and synthesized in this study. The structures of the new compounds were confirmed based on a comprehensive characterization of spectral data by applied IR and 1H as well as 13C NMR spectroscopy. The prepared compounds were tested for their anticancer and antimicrobial properties. Hydrazone 16b demonstrated convincing anticancer effect against all tested cell cultures such as human prostate carcinoma PPC-1 and human kidney carcinoma CaKi-1 cell lines, and human fibroblasts HF, n = 3. The most promising compound 16b showed higher activity against CaKi-1 cell line than the anticancer drugs axitinib and pazopanib used to treat renal cancer. Also, it was more active in the PPC-1 cell line compared to the approved PARP inhibitor Olaparib. Hydrazone 16b was also found to possess good antimicrobial properties against gram-positive bacteria strains of Staphylococcus aureus, Staphylococcus epidermidis, as well as Bacillus cereus.

New Ni(II) and Pd(II) complexes bearing derived sulfa drug ligands: synthesis, characterization, DFT calculations, and in silico and in vitro biological activity studies

In the present study, the synthesis of six new Ni(II) and Pd(II) complexes with three derived sulfamethoxazole drug ligands is reported. The coordination mode, geometry, and chemical formula of all the synthesized compounds have been determined by elemental analysis, mass spectrometry, emission atomic spectroscopy, conductivity measurements, magnetic susceptibility, FTIR, TGA, 1H-NMR, electronic absorption spectroscopy, SEM-EDX along with DFT calculations. The Schiff Base ligands were found to be bidentate and coordinated to the metal ions through sulfonamidic nitrogen and oxazolic nitrogen atoms leading to a square planar geometry for palladium (II) while a distorted octahedral geometry around Nickel (II) ion was suggested. Biological applications of the new complexes including in vitro antimicrobial, antioxidant and anticancer properties were investigated. The results showed that the new metal (II) compounds exhibit remarkable antibacterial inhibition activity against both Gram-positive and Gram-negative bacteria, in addition to noticeable DPPH free radical scavenging activity. The in vitro cytotoxicity assay of the complexes against cell lines of chronic myelogenous leukaemia (K562) showed promising potential for the application of the coordination compounds in antitumor therapy. Subsequently, to evaluate the pharmaceutical potential of the metal-containing compounds, pharmacokinetics and toxicity were studied by ADMET simulations while interactions between the complexes and bacterial proteins were evaluated by molecular docking.

Enhancing efficacy of existing antibacterials against selected multiple drug resistant bacteria using cinnamic acid-coated magnetic iron oxide and mesoporous silica nanoparticles

Developing new antibacterial drugs by using traditional ways is insufficient to meet existing challenges; hence, new strategies in the field of antibacterial discovery are necessary. An alternative strategy is to improve the efficacy of currently available antibiotics. Herein, the antibacterial efficacy of drugs (Cefixime, Sulfamethoxazole, and Moxifloxacin) and drug-loaded cinnamic acid-coated magnetic iron oxide and mesoporous silica nanoparticles (NPs) was elucidated versus Gram-negative bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae, neuropathogenic Escherichia coli K1 and Serratia marcescens) and Gram-positive bacteria (Methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Streptococcus pneumoniae, and Bacillus cereus). NPs were synthesized by co-precipitation and the Stöber method, and characterized by Fourier transform-infrared spectroscopy, Zetasizer, and Atomic force microscopy. Lactate dehydrogenase (LDH) assays were accomplished to determine drug cytotoxicity against human cells. Spherical NPs in the range of 118-362 nm were successfully synthesized. Antibacterial assays revealed that drugs conjugated with NPs portray enhanced bactericidal efficacies against multiple drug resistant bacteria compared to the drugs alone. Of note, Cefixime-conjugated NPs against Escherichia coli K1 and Methicillin- resistant Staphylococcus aureus, resulted in the complete eradication of all bacterial isolates tested at significantly lower concentrations compared to the antibiotics alone. Likewise, conjugation of Moxifloxacin resulted in the complete elimination of E. coli K1 and MRSA. Of note, nano-formulated drugs presented negligible cytotoxicity against human cells. These results depict potent, and enhanced efficacy of nano-formulated drugs against medically important bacteria and can be used as alternatives to current antibiotics. Future in vivo studies and clinical studies are warranted in prospective years to realize these expectations.

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.

An overview of metal-free synthetic routes to isoxazoles: the privileged scaffold

In the field of drug discovery, isoxazole is a five-membered heterocyclic moiety commonly found in many commercially available drugs. In view of their enormous significance, it is always imperative to unleash new eco-friendly synthetic strategies. Among various novel synthetic techniques in use for isoxazole synthesis, most synthetic methods employ Cu(i) or Ru(ii) as catalysts for (3 + 2) cycloaddition reaction. The particular disadvantages associated with metal-catalyzed reactions are high costs, low abundance, toxicity, a significant generation of waste, and difficulty to separate from the reaction mixtures. In view of these drawbacks, it is always imperative to develop alternate metal-free synthetic routes. This review article highlights a comprehensive overview on the potential application of metal-free synthetic routes for the synthesis of isoxazoles with significant biological interests.

Insight into Recent Drug Discoveries against Trypanosomatids and Plasmodium spp Parasites: New Metal-based Compounds

Scaffolds of metal-based compounds can act as pharmacophore groups in several ligands to treat various diseases, including tropical infectious diseases (TID). In this review article, we investigate the contribution of these moieties to medicinal inorganic chemistry in the last seven years against TID, including American trypanosomiasis (Chagas disease), human African trypanosomiasis (HAT, sleeping sickness), leishmania, and malaria. The most potent metal-based complexes are displayed and highlighted in figures, tables and graphics; according to their pharmacological activities (IC50 > 10µM) against Trypanosomatids and Plasmodium spp parasites. We highlight the current progresses and viewpoints of these metal-based complexes, with a specific focus on drug discovery.

Toxicity and combined effects of antibiotics and nano ZnO on a phosphorus-removing Shewanella strain in wastewater treatment

Antibiotics and nanoparticles, which are emerging contaminants, can occur simultaneously in biological wastewater treatment systems, potentially resulting in complex interactive effects. This study investigated the effects of individual and complex zinc oxide nanoparticles (nZnO) and antibiotics (quinolone and sulfonamide), on the Shewanella strain used to remove phosphorus (PO₄^3-), metabolic processes, as well as its complexing and toxicity mechanisms. The inhibition of PO₄^3- removal increased from 30.7% to 100.0% with increased nZnO concentrations (half maximal effective concentration (EC50) = 1.1 mg Zn/L) by affecting poly-p and glycogen metabolites. The combined exposure to nZnO and ciprofloxacin/norfloxacin (CIP/NOR) had a significant antagonistic effect on the removal of PO₄^3- and on the metabolism of poly-p and glycogen in phosphate-accumulating organisms (PAOs), whereas the complexing of sulfonamide and nZnO had no significant additional effect. Thus, the complexing of nanoparticles and antibiotics exhibited different toxicity effects from the antibiotic structure-based complex reactions. These results can be used to improve wastewater treatment processes and reduce risks associated with wastewater discharge.

Recent advances in drug discovery against Mycobacterium tuberculosis: Metal-based complexes

Metal-based drugs are privileged motifs that act as primary pharmacophores in bioactive compounds for various diseases, including tuberculosis (TB). This potentially life-threatening and extremely contagious infectious disease is caused by Mycobacterium tuberculosis (Mtb). In 2018, TB infected about 10 million people and caused 1.2 million deaths worldwide. A large number of ligands are promising scaffolds in drug design, including heterocyclic, phosphines, schiff bases, thio and semicarbazones, aliphatic amines, cyclopalladated, cyanometallates and miscellaneous. Moreover, several metal-based complexes have been studied for the treatment of numerous illnesses, including infectious diseases. To contribute to drug design, we identified the metal-based organometallic complexes against Mtb. Thus, in this review article, we analysed the recent contributions of metal-based scaffolds for design of new anti-Mtb drugs in the last decade (2011-2020). Besides, metal-based approaches will be presented in order to find out new antitubercular agents.