Polymer complexes. LXXV. Characterization of quinoline polymer complexes as potential bio-active and anti-corrosion agents

A comprehensive review on anti-inflammatory, antibacterial, anticancer and antifungal properties of several bivalent transition metal complexes

Transition metal complexes have been recognized as possible therapeutic agents, attributed to their special biological actions, including anti-inflammatory, antibacterial, antifungal, and anticancer. The pharmacological perspective connected with Copper (Cu), Cobalt (Co), Nickel (Ni), Manganese (Mn), Palladium (Pd), Zinc (Zn), and Platinum (Pt) metal(II) complexes is comprehensively explored in-depth in this research. The complexes show unique coordination chemistry and modes of action that help interactions with biological targets, including DNA binding, enzyme inhibition, and the formation of reactive oxygen species. All the metal(II) complexes showed notable potential impact in their perspective activity. Conspicuously, Co(II) and Ni(II) complexes show better antibacterial and antifungal action, while Cu(II) and Zn(II) combinations show higher anti-inflammatory activity. While research is constantly investigating alternative metal-based anticancer drugs like Pd(II), which seem to have lowered side effects, Pt(II) complexes especially cisplatin continue to be the benchmark in cancer treatment. Although the possible pharmacological actions are motivating, problems with toxicity and biocompatibility still provide major difficulties, especially in relation to Cd(II) and Hg(II) complexes. Strategies like ligand modification, nanoparticle-based delivery, and prodrug methods are used to increase selectivity and reduce side effects related to metal complexes. This review compiles the most recent developments and continuous research, thereby shedding light on the potential revolutionary power of metal(II) complexes in medical therapy. Understanding their mechanisms and enhancing their safety profiles will help us open the path to creative ideas for addressing some of the most urgent medical issues of today.

Synthesis, characterization, biological evaluation and molecular docking of a Schiff base ligand and its metal complexes

Condensation of 2,3-diaminopyridine with 2,4-dihyrodybenzaldehyde yielded a 4,4'-[(1E,1 ~ E)-(pyridine-2,3-diyl)bis(azanylylidene)]bis(methanylylidene)bis(benzene-1,3-diol) monobasic tridentate Schiff base ligand (HL) with an ONN donor sequence. Elemental analyses, conductivity tests, magnetic susceptibility data, FT-IR, UV-vis spectra, x-ray diffraction, and mass spectrum data of the ligand and its complexes were used for the characterization of the structures. Computational HF/3-21G calculations were performed to optimize their geometrical structures and assess their HOMO-LUMO energy gaps. The low molar conductance of the complexes indicates that they are not electrolytic. From the spectrophotometric and gravimetric analyses, the complexes (2-4) are in the ratio of 1:2, while complexes (1 & 5) (1:1) metal to ligand. 2,3-Diaminopyridine, 2,4-dihydroxybenzaldehyde, ligand (HL) and its complexes were screened for antibacterial and antifungal activities against some bacterial (Enterococcus faecalis, Salmonella typhi, and Staphylococcus epidermidis) and fungal isolates (Aspergillus flavus, Alternaria solani, and Candida albicans). The result reveals that 2,4-dihyrodybenzaldehyde has the strongest antibacterial activity among the other compounds followed by Mn(II) complex. The antimicrobial activity increases by increasing the compound concentration. To assess the inhibitory impact of ligand and its complexes on binding sites of B. cereus (PDB ID: 1FEZ), S. epidermidis (PDB ID: 3KP7), E. faecalis (PDB ID: 5V5U) and S. typhi (PDB ID: 5V2W) proteins, molecular modeling has been implemented offer a fresh concept for medication design. Molecular docking studies confirmed strong binding interactions between the metal complexes and bacterial proteins, validating their biological potential. These findings demonstrate the promising antimicrobial properties of Schiff base metal complexes, making them potential candidates for pharmaceutical and medicinal applications.

Versatile applications of cobalt and copper complexes of biopolymeric Schiff base ligands derived from chitosan

In the present study, biopolymeric Schiff base (SB) ligands were synthesized from chitosan and isatin. Consequently, their earth abundant transition metal complexes of cobalt and copper were synthesized. All compounds were extensively characterized using FTIR and UV spectroscopy, thermo-gravimetric (TG) analysis, X-ray powder diffraction (XRD) and FESEM (field emission scanning electron microscopy). The impetus of this study was to explore different applications of the same transition metal complexes, thereby converting them to broad spectrum antimicrobial drugs and to useful chemical catalysts. Thus, these cobalt and copper complexes were applied as anti-bacterial and anti-fungal agents and in reductive degradation of common pollutants. Specifically, chitosan, and all synthesized compounds were investigated against fungal species, namely, Candida and Aspergillus, and bacterial species, like Pseudomonas syringae, Escherichia coli, Staphylococcus aureus and Staphylococcus epidermis. All compounds demonstrated promising antimicrobial activity. Chitosan-modified compounds demonstrated a high antifungal activity against Candida albicans and possessed superior antibacterial action than free chitosan. Additionally, catalytic ability in reductive degradation of common dyes, methylene blue (MEB), Congo red (CR) and methyl orange (MO), was investigated. These dyes were conveniently degraded in presence of metal complexes, whereas neither chitosan nor the Schiff base ligand derived from it could carry out similar reaction.

Nitro Substituted Co(II), Ni(II) and Cu(II) Schiff Base Metal complexes: design, spectral analysis, antimicrobial and in-silico molecular docking investigation

The Schiff base metal complexes containing the transition metal ions Co(II), Ni(II) and Cu(II) were synthesized using their nitrate and acetate salts. An octahedral environment encircling metal complexes has been demonstrated by the findings of multiple spectroscopic approaches that were employed to demonstrate the structure of the metal complexes. The Coats-Redfern method of thermal analysis was employed to carry out the kinetic and thermodynamic calculations. The crystalline size of ligand was 36.67 nm and for the metal complexes it varies from 22.43 to 49.21 nm. To assess the biological effectiveness of these compounds, molecular docking studies were emanated. The docking binding studies were established through the interaction of metal complexes with human cancer protein, such as 3W2S (ovarian cancer) and 4ZVM (breast cancer). The results exemplified that the complexes are more efficient towards ovarian cancer (3W2S) in contrast to breast cancer (4ZVM) while among complexes, the nickel acetate (- 7.0 kcal/mol) and copper acetate (- 7.9 kcal/mol) complex were more efficient towards 4ZVM and 3W2S receptors respectively. Additionally, DNA binding studies against 1BNA receptor protein was examined from docking evaluations and the finding concludes the highest efficiency of nickel (- 8.1 kcal/mol) complexes. Further, a number of bacterial and fungal strains have been implemented in antimicrobial examinations to assess the compounds effectualness. The results untangled the extreme potential of copper nitrate (0.0051-0.0102 µmol/mL) and copper acetate (0.0051-0.0103 µmol/mL) complexes against all bacterial and fungal strains except for S. aureus in which nickel acetate proved out to be highly competent.

Theoretical and experimental investigation of mixed-ligand metal(II) Schiff base complexes using maleic acid as the auxiliary ligand

This work is focused on the synthesis of several transition metal complexes [ML(MA)], where M = Copper (II), Zinc (II), Cobalt (II) and Nickel (II), MA = maleic acid and L = Schiff base generated from benzene-1,2-diamine [o-phenylenediamine] and 4-chlorobenzaldehyde. The characterization using Fourier-Transform Infrared, Nuclear Magnetic Resonance spectroscopy, Ultraviolet-Visible spectra, Mass, Electro Paramagnetic Resonance and elemental analysis confirm the square planar geometry of the complexes. The in vitro antimicrobial potential of the complexes has been tested by the broth dilution method and the antioxidant method has been done by free radical scavenging analysis. The in vitro methods reveal the outstanding biological characteristics of the copper complexes. The molecular structure of the ligand and its metal (II) complexes has been optimized using Density Functional Theory studies performed by the Gaussian-09 software and their parameters have been discussed. Natural Bond Orbital and Frontier Molecular Orbital analyses have assessed the presence of a metal-ligand bond in complexes. In addition, molecular docking studies have also been performed on antiviral activity of all the complexes using a viral protein and their interacting amino acids.

Effects of polymer carriers on the occurrence and development of autophagy in drug delivery

Autophagy is an evolutionarily conserved catabolic process that can degrade cytoplasmic materials and recycle energy to maintain metabolite homeostasis in cells. Autophagy is closely related to various physiological or pathological processes. Macromolecular materials are widely used in drug delivery systems and disease treatments due to their intrinsic effects, such as altered pharmacokinetics and biodistribution. Interaction of autophagic flux or the signal pathway with macromolecules may cause autophagy inhibition or autophagy cell death. This review covers autophagy regulation pathways and macromolecular materials (including functional micelles, biodegradable and pH-sensitive polymers, biomacromolecules, dendrimers, coordination polymers, and hybrid nanoparticles) mediated autophagy modulation.

Synthesis, structural characterization, molecular docking study, biological activity of carbon monoxide release molecules as potent antitumor agents

In this study, two series of novel carbon monoxide-releasing molecules (CO-RMs) containing Co were designed and synthesized. The synthesized complexes were characterized by IR, ESI-MS, ¹H NMR and ¹³C NMR spectroscopies. The antitumor activity of all complexes on HepG2 cells, Hela cells and MDA-MB-231 cells were assayed by MTT. IC₅₀ values of complexes 1-13 were 4.7-548.6 µM. Among these complexes, complex 1 was presented with a high selectivity to HepG2 cells (IC₅₀ = 4.7 ± 0.76 μM). Compared with iCORM (inactive CORM), CORM (complex 1) showed a remarkable activity against tumor cells owing to co-effect of CO and the ligand of COX-2 inhibitor. In addition, complex 1 increased ROS in mitochondria and caused a decrease of dose-dependent mitochondrial membrane potential against HepG2 cells. Complex 1 down-regulated the expression of COX-2 protein in western blot analysis. The molecular docking study suggested that the complex 1 formed a hydrogen bond with amino acid R120 in the active site of the Human cyclooxygenase-2 (COX-2). Therefore, the complex 1 could induce apoptosis of HepG2 cells through targeting COX-2 and mitochondria pathways, and it maybe a potential therapeutic agent for cancer.

Recent update on antibacterial and antifungal activity of quinoline scaffolds

Although most of the heterocycles have been reported to possess a significant pharmacological activity, only a few of them, namely quinoline derivatives, have exhibited the finest biological activities. Despite the few medicinal properties of the plain quinoline molecule, its derivatives exhibit diverse pharmacological properties such as anticancer, anti-inflammatory, antibacterial, antiviral, antifungal, antiprotozoal activities, and so on. The potential antimicrobial properties of the quinoline derivatives are evident from the decades of research on these derivatives. Owing to limitations like drug resistance, high cost, severe side effects, and less bioavailability of previously synthesized antimicrobial agents, these drugs have become obsolete in recent years. Hence, the design of more efficient antimicrobial drugs must be given topmost priority. A breakthrough in drug discovery is a must to prevent malevolent microbial diseases. Addressing all these issues, researchers have been continuously contributing to antimicrobial drug discovery. Herein, a short description of the pharmacology of antimicrobial agents such as antibacterials and antifungals synthesized recently is provided. The versatile derivatization of the quinoline moiety leading to significant antimicrobial potencies is discussed, considering the structure-activity relationship.

Five new complexes with deferiprone and N,N-donor ligands: evaluation of cytotoxicity against breast cancer MCF-7 cell line and HSA-binding determination

In this study, five new complexes containing deferiprone (dfp) and N,N-donor ligands [bipyridine (bpy), 1,10-phenanthroline (phen) and ethylenediamine (en)] were synthesized: [Fe(dfp)₂(bpy)](PF₆) (1), [Fe(dfp)₂(phen)](PF₆) (2), [Cu₂(dfp)₂(bpy)₂](PF₆)₂ (3), [Ga(dfp)₂(bpy)](PF₆) (4), and [Fe(dfp)₂(en)](PF₆) (5). Characterization of these complexes was carried out through elemental analysis and FT-IR, and single-crystal X-ray crystallography was used to determine their structures. Whilst the polyhedron has a distorted octahedral geometry in 1, 2, 4, and 5, it adopts a distorted square-pyramidal geometry in 3. Interaction of these compounds with human serum albumin (HSA) has been investigated through electronic absorption and fluorescence titration techniques. Emission quenching was performed separately for each complex at three different temperatures and thermodynamic parameters were calculated using binding constants to better understand the power of different binding forces with the HSA. Results demonstrated that compounds interact strongly with the HSA with a static quenching mechanism. Our evaluation of the cytotoxicity of complexes against the breast cancer MCF-7 cell line showed that complex 2 presents a better cytotoxicity than the standard cis-Pt. Finally, using the AutoDock 4.2 program, simulations to analyze the mechanism of complex-HSA interactions and their binding mode were carried out. Results showed that the best binding mode is located in subdomain IB for 1, 2, and 4, in I/II for 3, and in IA/IIA for 5. Communicated by Ramaswamy H. Sarma.

Antimicrobial and antiproliferative activity studies of some new quinoline-3-carbaldehyde hydrazone derivatives

In this study, a total of 22 piece quinoline-3-carbaldehyde hydrazone derivative compounds were designed and synthesized, 2 of which were not original, their antimicrobial activities were determined with microdilution method and their in vitro cytotoxic effect was investigated in MCF-7 and A549 cells by MTT assay. When the activity results are examined, although the antimicrobial effects of quinoline derivatives, in general, are weaker than standard drugs; 3q5 and 3q6 against MRSA showed promising activity with MIC:16 µg/ml compared to reference drugs. Compounds generally showed weaker cytotoxic activity on the A549 and MCF-7 cell line. 3q12, 3q17 and 3q22 at 100 µM reduced cell viability to 59.28%, 76.24% and 72.92% on A549 cells, respectively. Compound 3q6, one of the most effective compounds against MRSA, formed a 2.10 Å long hydrogen bond between the quinoline nitrogen and ARG132 in the DNA topoisomerase IV active site (PDB: 3FV5). Theoretical ADME profiles of all compounds comply with Lipinski and other limiting rules. In addition, MEP analysis of 3q6, geometric optimization and molecular reactivity analysis were calculated with the 6-311G (d,p) base set DFT/B3LYP theory, and ΔE = E_LUMO-E_HOMO, which is a measure of the stable structure of the molecule, was calculated as 0.13377 for 3q6 and had the most stable electronic structure among all compounds.

FRET-based fluorescent nanoprobe platform for sorting of active microorganisms by functional properties

Fluorescence-activated cell sorting (FACS) has rarely been applied to screening of microorganisms because of poor detection resolution, which is compromised by poor stability, toxicity, or interference from background fluorescence of the fluorescence sensors used. Here, a fluorescence-based rapid high-throughput cell sorting method was first developed using a fluorescence resonance energy transfer (FRET) fluorescent nanoprobe NP-RA, which was constructed by coating a silica nanoparticle with Rhodamine B and methyl-red (an azo dye). Rhodamine B (inner layer) is the FRET donor and methyl-red (outer layer) is the acceptor. This ready-to-use NP-RA is non-fluorescent, but fluoresces once the outer layer is degraded by microorganisms. In our experiment, NP-RA was ultrasensitive to model strain Shewanella decolorationis S12, showing a broad detection range from 8.0 cfu/mL to 8.7 × 10⁸ cfu/mL under confocal laser scanning microscopy, and from 1.1 × 10⁷ to 9.36 × 10⁸ cfu/mL under a fluorometer. In addition, NP-RA bioimaging can clearly identify other azo-respiring cells in the microbial community, including Bosea thiooxidans DSM 9653 and Lysinibacillus pakistanensis NCCP-54. Furthermore, the fluorescent probe NP-RA is compatible with downstream FACS so that azo-respiring cells can be rapidly sorted out directly from an artificial microbial community. To our knowledge, no fluorescent nanoprobe has yet been designed for tracking and sorting azo-respiration functional microorganisms.