Two perfectly cromulent ferrocene containing ruthenium(II)-arene antibacterial agents

The evolution of high virulence bacterial strains has necessitated the development of novel therapeutic agents to treat resistant infections. Metal-based therapeutics represent a promising avenue for advancement, given their structural variability and unique modes of action relative to classical organic molecules. One strategy that has seen marked success is the incorporation of ferrocene into the framework of established antibacterial agents, while ruthenium-based complexes have also shown promise as bioactive compounds. This work focused on the preparation of novel ruthenium(II)-arene complexes containing Schiff base ligands with an attached ferrocene, and evaluation of their antibacterial activity. Structure-activity relationships identified the importance of having a phenyl group between the Schiff base imine and the appended ferrocene. This complex, C2, showed prominent activity against several clinically relevant bacterial strains, including a minimum inhibitory concentration of 16 μg mL-1 for methicillin-resistant Staphylococcus aureus (MSRA). Overall, the results of this study represent a promising new lead for future development of novel antibacterial agents.

Two Schiff bases were synthesized from raceacetophenone: 1) ADS1 4-ethyl-6-{(E)-1-[(3-nitrophenyl)imino]ethyl}benzene-1,3-diol and 2) ADS3 4-ethyl-6-[(E)-1-{(2-nitrophenyl)imino]ethyl}benzene-1,3-diol. Then their metal complexes were formed. The metals selected for the preparation of complexes were copper, nickel, iron and zinc. Hence, in total 8 metal complexes were synthesized and screened for antibacterial activity against some clinically important bacteria, such as Pseudomonas aeruginosa, Proteus vulgaris, Proteus mirabilis, Klebsiella pneumoniae and Staphylococcus aureus. The in vitro antibacterial activity was determined by the Agar Ditch technique using DMF (polar) and 1,4-dioxane (non polar) as solvents. The Schiff bases showed greater activity than theirmetal complexes; themetal complexes showed differential effects on the bacterial strains investigated and the solvent used, suggesting that the antibacterial activity is dependent on the molecular structure of the compound, the solvent used and the bacterial strain under consideration. The Schiff base ADS3 in the polar solvent DMF showed better antibacterial activity towards the investigated bacterial strains. Amongst the four metals, Zn showed the best antibacterial activity followed by Fe in 1,4-dioxane while Ni followed by Zn and Fe showed the best antibacterial activity in DMF. P. vulgaris was the most resistant bacteria.

A series of Ferrocene Schiff bases derived from glycine and their cobalt (II), copper (II), nickel (II), and zinc (II) metal complexes have been synthesized and characterized by IR, 1H NMR, MS and elemental analysis, the results conformed well with expected structures. The synthesized ligands, along with their metal (II) complexes, were screened in vitro for their antibacterial activity against three Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains. The results showed that the metal (II) complexes are more potent in antibacterial activity against one or more species in comparison with those of uncomplexed ligands.

Novel Schiff base ligand derived from condensation reaction between 3-Amino-4-Hydroxy Benzoic Acid and 2-hydroxy-5-nitrobenzaldehyde. Fe (III), Co (II) & Ni (II) metal complexes were formed from the synthesized ligand. FT-IR, UV- Visible 1H-NMR & HRMS Characterization studies were carried out for the confirmation of the structure and bonding of the synthesized ligand and its complexes. Complexes were tested for their antibacterial and antifungal activities using gram positive bacterial strains i.e. Staphylococcus aureus and Bacillus subtilis, gram negative bacterial strains i.e. Escherichia coli and Pseudomonas aeruginosa by disc diffusion method and antifungal activity was carried out using Aspergillus Niger fungal strain. It has been found that complexes and ligand show potent antibacterial and antifungal activities. Keywords: Schiff base, Metal complexes, Antibacterial activity, Antifungal activity

Complexation of trichlorosalicylic acid with alkaline and first row transition metals as a switch for their antibacterial activity

Cobalt(II), nickel(II), palladium(II) and zinc(II) metallothiosemicarbazones: Synthesis, characterization, X-ray structures and biological activity

Complexes of Mn(II), Fe(II) and Co(II) with a Schiff base derived from condensation reaction of thiourea and o-anisaldehyde has been synthesized and characterized analytically and spectroscopically. Melting point of the Schiff base was found to be 160°C and the complexes decomposed within a temperature range of 215 to 275°C. Molarconductances of the complexes were found to be within 1.1 to 3.5W–1 cm2 mol–1 range. Magnetic moment indicated the complexes to be paramagnetic (4.03 to 5.71BM). Infrared spectrum of the Schiff base showed the azomethine peak at 1601cm–1 which shifted up to1687cm–1 in the complexes. The analytical and spectral studies revealed that all the metal(II) complexes are in 1:3 metal ligand ratio, with the Schiff base acting as tetradentate ligand towards the metal ion via azomethine – N, and methoxy –O and two chlorine atoms were further coordinated to the metal(II) ion. The synthesized ligand and its respective metal (II) complexes were screened for their antibacterial activity against Staphylococcus aureus and Escherichia coli strains and antifungal activity against Aspergillus flavus and Mucorindicus. The results revealed that, the Schiff base and the metal (II) complexes showed significant antibacterial and antifungal activities at high concentration.Keywords: Metal complexes, thiourea, anisaldehyde, characterization, antimicrobial

Synthesis, spectroscopic characterization and antimicrobial studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with Schiff bases derived from 5-bromo-salicylaldehyde

Triazole derived Schiff bases and their metal complexes (cobalt(II), copper(II), nickel(II), and zinc(II)) have been prepared and characterized using IR, 1H and 13C NMR, mass spectrometry, magnetic susceptibility and conductivity measurements, and CHN analysis data. The structure of L2, N-[(5-methylthiophen-2-yl)methylidene]-1H-1,2,4-triazol-3-amine, has also been determined by the X-ray diffraction method. All the metal(II) complexes showed octahedral geometry except the copper(II) complexes, which showed distorted octahedral geometry. The triazole ligands and their metal complexes have been screened for their in vitro antibacterial, antifungal, and cytotoxic activity. All the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. It is revealed that all the synthesized complexes showed better activity than the ligands, due to coordination.

Antibiotics or antimicrobial agents are the most significant utilized secondary metabolites, which are commonly synthesized by soil bacteria and fungi and found to be effective. Most of the antibiotics used are derived from the soil bacteria and Actinomycetes. Antibiotic resistance poses a serious global health threat, making infections harder to treat, potentially leading to longer illnesses, more complications, increased healthcare costs, and even death. The present research project has been designed to identify and characterize the antibiotic-producing bacteria from the waste soil samples collected from ten different Pharmaceutical Industrial waste soils of Hattar, Haripur, using standard microbiological techniques. Objective: To isolate, identify, and characterize antibiotic-producing bacterial strains from pharmaceutical industrial waste soils, and to evaluate their antibacterial activity against selected MDR pathogens. Methods: Overall, 10 bacterial strains were isolated from waste soil of Pharmaceutical industries to examine their antibacterial activity against four tested pathogens, such as Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus, by using the well diffusion method. Only four bacterial strains out of ten showed high antibacterial activity against these selected MDR pathogens. The isolated bacterial strains were initially identified through Gram staining and biochemical tests. For molecular identification, the MALDI TOF technique was used. Results: The isolated strains S1 and S6 were Enterobacter cloacae, S2 was Enterobacter asburiae, and S8 was identified as Pseudomonas aeruginosa. Then the crude extracts of S1, S2, S6, and S8 were further analyzed by GC-MS to identify the compounds present, in which almost 300 compounds were identified, and out of 300 compounds, some of them (D-Glycero-D-Gulo-Heptonic Acid, D-(+)-Ribonic Acid.Gamma.-Lac, Oxalic Acid, Ethyl Neopentyl E, D-Glycero-D-Gulo-Heptonic Acid, Hentriacontane, Neopentyl Glycol, Strychane, 1-Acetyl-20.Alpha, 3,4-Altrosan, Carbamic Acid, Hydroxy-, Ethyl, etc) were found in previous literature showing anti-microbial, anti-bacterial, anti-fungal, anti-inflammatory, anti-tumor, and anti-cancerous activities. Some new compounds were also detected. Further research of the identified compounds may detect some more effective antibacterial agents against selected MDR pathogens (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus). Conclusion: Bacteria present in waste soil samples of Pharmaceutical industries have the potential to show antibacterial activity against selected MDR pathogens (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus), and biologically active compounds having antibacterial properties may be extracted from these bacterial isolates.

Bacterial resistance, accelerated by the misuse of antibiotics, remains a critical concern for public health, promoting an ongoing exploration for cost-effective and safe antibacterial agents. Recently, there has been significant focus on various nanomaterials for the development of alternative antibiotics. Among these, molybdenum disulfide (MoS2) has gained attention due to its unique chemical, physical, and electronic properties, as well as its semiconducting nature, biocompatibility, and colloidal stability, positioning it as a promising candidate for biomedical research. The impact of the shape and size of MoS2 nanomaterials on the antibacterial activity remains largely unexplored. In this study, we investigated the effect of the shape and size of MoS2 nanomaterials, such as quantum dots, nanoflowers, and nanosheets, on antimicrobial and anti-biofilm activity. As we had established earlier, functionalization with positively charged thiol ligands can enhance colloidal stability, biocompatibility, and antibacterial efficacy; we functionalized all targeted nanomaterials. Our results revealed that functionalized MoS2 quantum dots (F-MQDs) exhibited superior activity compared to functionalized MoS2 nanoflowers (F-MNFs) and functionalized MoS2 nanosheets (F-MNSs) against Staphylococcus aureus (SA), both drug-resistant (methicillin) and nonresistant strains. We observed very low minimum inhibitory concentration (MIC, 30 ng/mL) for F-MQDs. The observed trend in antibacterial efficacy was as follows: F-MQDs > F-MNFs ≥ F-MNSs. We explored the relevant mechanism related to the antibacterial activity where the balance between membrane depolarization and internalization plays the determining role. Furthermore, F-MQDs show enhanced anti-biofilm activity compared to F-MNFs and F-MNSs against mature MRSA biofilms. Due to the superior antibacterial and anti-biofilm activity of F-MQDs, we extended their application to wound healing. This study will help us to develop other appropriate surface modified nanomaterials for antibacterial and anti-biofilm activity for further applications such as antibacterial coatings, water disinfection, and wound healing.

Synthesis, characterization, DNA interaction, BSA/HSA binding activities of VO(IV), Cu(II) and Zn(II) Schiff base complexes and its molecular docking with biomolecules

The bio-constituents of medicinal plants are greatly influenced by the environmental conditions and growing seasons. This study aimed to uncover the presence of different metabolites and to investigate the biological properties of the leaves of Mangifera indica during summer and winter seasons. The extract of M. indica leaves for summer and winter using different solvent extracts (hexane, chloroform, and methanol) showed the presence of phenols, flavonoids, tannins, terpenoids, alkaloids, phytosterol, saponins, steroids, and carbohydrates. Antibacterial activity of the methanolic leaf extracts for summer and winter were evaluated against the bacterial species Staphylococcus aureus (ATCC 43300) and Escherichia coli (ATCC 25922). For S. aureus (ATTC 43300), the summer crude extract displayed lower antibacterial activity than the control streptomycin, with zones of inhibition of 14.17 and 16.67 mm, respectively. Winter extracts had a zone of inhibition of 12 mm, while streptomycin had a 13.67 mm zone of inhibition. For E. coli (ATCC 25922), the summer crude extract displayed higher antibacterial activity than the control gentamycin, with zones of inhibition of 18.05 and 17.5 mm, respectively. The winter extracts had a zone of inhibition of 8.5 mm, while gentamycin had a 14.5 mm zone of inhibition. Antibacterial screening showed positive results for both seasons; however, summer extracts showed a more potent effect. The antioxidant screening was conducted using 2,2-diphenyl-1-picryl hydrazyl radical (DPPH) assay. Potent radical scavenging activity was exhibited for both summer and winter seasons with hexane and methanolic extracts for summer (IC50 of 19.53 μg/mL and 12.71 μg/mL, respectively) and winter (22.32 μg/mL and 14.35 μg/mL, respectively) in comparison to the control ascorbic acid, which produced an IC50 of 3.20 μg/mL. The summer leaf extracts had better radical scavenging IC50 capacity than winter extracts. In conclusion, hexane and methanolic extracts had significant antioxidant activity, while methanolic extracts exhibited antibacterial activity. Further studies are required against more strains of bacteria and cancer cell lines to test for potency.

This study presents the synthesis and characterization of five metal complexes (C1–C5) derived from the reaction of a newly synthesized ligand (HL) with various metal chlorides, specifically Zn, Co, Ni, Mn, and Fe. General Background: Transition metal complexes have garnered significant interest due to their diverse biological activities and potential therapeutic applications. Specific Background: The ligand (HL) was synthesized from equimolar amounts of p-anisidine and salicylaldehyde, yet the influence of different metal ions on the biological properties of such complexes remains underexplored. Knowledge Gap: While several metal complexes exhibit antimicrobial properties, there is limited research on the biological activities of complexes formed with this specific ligand. Aims: This work aims to synthesize and characterize the metal complexes and evaluate their antibacterial activity against various bacterial strains. Results: Characterization via FT-IR and ¹H NMR spectroscopy confirmed the successful formation of the complexes, indicating strong metal-ligand interactions. Preliminary biological testing revealed varying degrees of antibacterial activity among the complexes, with notable effectiveness against certain bacterial strains. Novelty: The study contributes to the understanding of how different metal ions influence the biological properties of metal-ligand complexes. Implications: These findings suggest that the synthesized metal complexes could serve as potential candidates for further development in antimicrobial therapies, prompting additional research into their mechanism of action and broader biological applications.

Synthesis, cytotoxicity and antibacterial activities of ruthenium, rhodium and iridium metal complexes containing diazafluorene functionalized ligands