Schiff base metal complexes of 4-methyl-1H-indol-3-carbaldehyde derivative as a series of potential antioxidants and antimicrobial: Synthesis, spectroscopic characterization and 3D molecular modeling

Recent Development on Copper-Sensor and its Biological Applications: A Review

Metal ion recognition is one of the most prospective research topics in the field of chemical sensors due to its wide range of clinical, biological and environmental applications. In this context, hydrazones are well known compounds that exhibit metal sensing and several biological properties due to the presence of N=CH- bond. Some of the biological properties includes anti-cancer, anti-tumor, anti-oxidant, anti-microbial activities. Hydrazones are also used as a ligand to detect metal ion as well as to generate metal complexes that exhibit medicinal properties. Thus, in recent years, many attempts were made to develop novel ligands with enhanced metal sensing and medicinal properties. In this review, some of the recent development on the hydrazones and their copper complexes are covered from the last few years from 2015-2023. These includes significance of copper ions, synthesis, biological properties, mechanism and metal sensing properties of some of the copper complexes were discussed.

New Insights into the Modifications and Bioactivities of Indole-3- Carboxaldehyde and its Derivatives as a Potential Scaffold for Drug Design: A Mini-Review

Indole, a ubiquitous structural motif in bioactive compounds, has played a pivotal role in drug discovery. Among indole derivatives, indole-3-carboxaldehyde (I3A) has emerged as a particularly promising scaffold for the development of therapeutic agents. This review delves into the recent advancements in the chemical modification of I3A and its derivatives, highlighting their potential applications in various therapeutic areas. I3A derivatives have demonstrated a wide range of biological activities, including anti-inflammatory, anti-leishmanial, anti-cancer, anti-bacterial, antifungal, and anti-HIV properties. The structural modifications introduced to the I3A scaffold, such as substitutions on the indole ring (alkylation/arylation/halogenation), variations in the aldehyde group via condensation (Aldol/Claisen/Knoevenagel), and molecular hybridization with other reputable bioactive compounds like coumarins, chalcones, triazoles, and thiophenes, contribute to these activities. Beyond its therapeutic potential, I3A has also found applications as a ligand for Schiff base synthesis, a polymer, and a chromophore. This review provides a comprehensive overview of the latest research on I3A and its derivatives, focusing on the key reactions, modification pathways, reaction conditions, yields, and associated therapeutic activities. By understanding these advancements, researchers can gain valuable insights into the potential applications and future directions for I3A-based drug discovery.

Antioxidant activity of Schiff base ligands using the DPPH scavenging assay: an updated review

Schiff base ligands, formed from primary amines and carbonyl compounds, are potential antioxidants because they scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals via hydrogen atom transfer (HAT) and single electron transfer (SET) routes. This review aims to help design, synthesize, and discuss the antioxidant activity of Schiff base ligands based on their structure. This study critically discussed the solvent effect and the structural changes of Schiff base ligands responsible for DPPH scavenging activity, such as proton donating, electron-donating, and electron-withdrawing substituents, conjugation and ring structure. The ligands with electron-donating substituent groups in the phenolic ring demonstrated greater activity by readily stabilizing the radical and some of them showed higher activity than the standard. The activity also depends on the solvent used; the activity increases in those solvents that promote the proton and electron donation of the Schiff base. Schiff bases are most important due to their versatile applications, which can be explained by their antioxidant activity. The data led to the conclusion that the Schiff base ligand will serve as a source of synthetic antioxidants. There should be lots of scope for research on the antioxidant activity of Schiff bases. This review will assist researchers in studying Schiff base-based antioxidants and their applications. All the data analyzed in this paper was found from in vitro tests; for more clearance supplementary tests and in vivo investigations are crucial.

Hydrazone-containing organotin(IV) complexes: synthesis, characterization, antimicrobial, antioxidant activity and molecular-docking studies

The diorganotin(IV) complexes (5-20) were synthesized in the present research from 4-fluorophenoxyacetic hydrazide and salicylaldehyde derivatives-based hydrazone ligands (1-4) to get an effective biological agent to combat microbial and oxidant deformities. Numerous spectral techniques such as (1H, 13C, 119Sn) NMR, UV-Vis, IR, and mass spectrometry were executed to illuminate the composition of complexes. These techniques ascertained tridentate chelation of hydrazone ligands with tin metal through enolic, phenolic oxygens and imine nitrogen, revealing pentacoordinated geometry of the complexes. The single crystal XRD of complex (5) confirmed distorted trigonal bipyramidal geometry. The TGA studies showed thermal stability up to 180 °C of the complexes, whereas the low conductance observed pointed to the non-electrolytic nature of the compounds. Furthermore, serial dilution assay was implemented to uncover the microbial inhibition efficacy (against six strains) of the compounds using ciprofloxacin and fluconazole. Among the synthesized compounds, (1, 8) exhibited comparable MIC value to standard. The compound (8) was reported as four times more potent than the fluconazole against C. albicans. Using DPPH assay, the antioxidant efficiency was examined which advocates enhanced efficacy of complexes than the ligands. The potency of complex (8) against C. albicans makes it a point of interest for molecular docking investigation, so, complex (8) and its ligand (1) were studied against protein of C. albicans (5TZ1), revealing the more efficacy of complex (binding energy-11.6 kcal/mol) than ligand. Further, the compounds were analysed for ADME prediction which concluded the efficacy of compounds as orally efficient pharmaceuticals.

Indole-Containing Metal Complexes and Their Medicinal Applications

Indole is an important element of many natural and synthetic molecules with significant biological activity. Nonetheless, the co-presence of transitional metals in organic scaffold may represent an important factor in the development of effective medicinal agents. This review covers some of the latest and most relevant achievements in the biological and pharmacological activity of important indole-containing metal complexes in the area of drug discovery.

Synthesis, structural characterization, antioxidant, cytotoxic activities and docking studies of schiff base Cu(II) complexes

By combining hydrazide with 2-Acetylpyridine, a hydrazone ligand (HL) was successfully created. Several copper (II) salts have been used to create three copper (II) hydrazone complexes (acetate, sulphate, and chloride). The hydrazide ligand and its copper (II) complexes (1-3) were studied via variety of analytical techniques, including elemental analysis, electronic, infrared, UV-vis Spectrum, XRD study, thermal analysis, also molar conductivity amounts. The spectrum results indicate that in all complexes, the ligand exhibits monobasic tridentate behavior. Octahedral geometries were present in all metal complexes. The Coats-Redfern equations were used to compute and describe the dynamics properties of several steps of TGA (Ea, A, ΔH*, ΔS*, and ΔG*). Calculations using the density functional theory (DFT) were done at the molecular studio software toward examine ligands agent's and its complexes' best structures. The MCF-7 in addition to HepG-2 cell lines was resistant to tumor-inducing effects of the copper (II) chelates. The in vitro antioxidant capacities of all complexes have been estimated via DPPH free radical scavenger assays. Furthermore, zones of inhibition length accustomed to test antimicrobial effect of particular complexes in vitro towards Staphylococcus aureus (Gram positive bacteria) E. coli (Gram negative bacteria). Both absorption spectra and viscosity measurements in calf thymus DNA binding have been used to study the complexes. In order to explore docking research of copper (II) chelates, the crystallographic construction of the SARS-active CoV-2's site protein (PDB ID:6XBH) was used (COVID-19) and breast cancer distorted (PDB ID: 3hb5).

Synthesis, characterization, DFT calculations and biological activity of new Schiff base complexes

Schiff bases ligand (HL) was produced by condensing 4-aminobenzohydrazide with N-(4-chlorophenyl)-2-(4-formylphenoxy)acetamide. Cobalt (II), nickel (II), and copper (II) acetate and ligand are reacted to form 1:1 complexes. By using electronic spectra, magnetic susceptibility measurements, infrared data from 1H NMR, and XRD studies, the ligand and its metal complexes have been characterized. According to the spectrum data, the ligand functions as a monobasic bidentate, coordinating with the nitrogen atom of azomethine (-C[bond, double bond]N-) group and the oxygen atom of carbonyl group in enol form. An octahedral structure has been proposed for Co(II), Ni(II), and Cu(II) complexes according to magnetic and electronic spectrum analysis. Using the DFT method, the computational investigations of the ligand and its metal complexes showed the bond lengths, bond angles, and quantum chemical parameters. To determine the thermal stability and mode of thermal degradation of hydrazone ligand and its complexes, thermogravimetric analysis was approved out on the samples. Two calculated method, Horowitz-Metzger and Coats-Redfern, were used to calculate the characteristics of the composites' thermal degradation mechanisms at each step, including their breakdown kinetics. The ligand and its complexes were investigated for their cytotoxicity in vitro compared to human amnion (WISH) and epitheliod carcinoma (Hela). The Ni(II) complex showed highly inhibition against (WISH) growth (IC50 = 18.28±1.8 μM) with relationship to the produced chemicals and other common medications. The interaction between the ligand and its complexes with the genetic tumor (3hb5) receptor was examined using docking experiments.

Water-soluble nickel (II) Schiff base complexes: Synthesis, structural characterization, DNA binding affinity, DNA cleavage, cytotoxicity, and computational studies

Two water-soluble nickel (II) Schiff base complexes were prepared and their interaction with fish sperm DNA (FS-DNA) was investigated by various methods including UV-vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscometric measurements. Complex 1: [N,N'-bis{5-[(triphenyl phosphonium chloride)-methyl] salicylidine}-3,4-diaminobenzophenone]nickel(II) perchloride dihydrate: [Ni(5-CH₂PPh₃-3,4-salophen)] (ClO₄)₂.2 H₂O was synthesized as a new complex and characterized by elemental analysis, IR, ¹H NMR, thermal gravimetric analysis (TGA) and UV-vis spectroscopy. Complex 2: sodium [(N,N'-bis(5-sulfosalicyliden)-3, 4-diaminobenzophenone)aqua] nickel(II) hydrate: Na₂[Ni (5-SO₃-3,4-salbenz)(H₂O)]. H₂O was already synthesized by our research team, but in this study, its function as a DNA-binding compound was tested, and compared with the results of complex 1-DNA binding. The calculation of different constants using absorption and emission data, all confirmed the stronger binding ability of complex 1 than complex 2 with DNA. Different thermodynamic parameters showed the interactions between DNA and complexes were the type of hydrophobic interaction for complex 1 and electrostatic interaction for complex 2. Also, the negative values of free energy changes proved a spontaneous DNA binding process. Based on cell toxicity assay against two different cell lines including Jurkat and MCF-7, the effect of complex 1 was comparable to cisplatin, and the toxicity mechanism was further justified by bright field microscopy, flow cytometry, and cleavage of DNA in the presence of H₂O₂. Besides, the docking calculations suggested intercalation after measuring the lowest-energy between the complexes and DNA. For both complexes, all analytical, spectroscopic, and molecular modeling methods supported partial intercalation as the main binding mode between the complexes and DNA.

Molecular Docking, DFT Calculations, Effect of High Energetic Ionizing Radiation, and Biological Evaluation of Some Novel Metal (II) Heteroleptic Complexes Bearing the Thiosemicarbazone Ligand

New Pb(II), Mn(II), Hg(II), and Zn(II) complexes, derived from 4-(4-chlorophenyl)-1-(2-(phenylamino)acetyl)thiosemicarbazone, were synthesized. The compounds with general formulas, [Pb(H₂L)₂(OAc)₂]ETOH.H₂O, [Mn(H₂L)(HL)]Cl, [Hg₂(H₂L)(OH)SO₄], and [Zn(H₂L)(HL)]Cl, were characterized by physicochemical and theoretical studies. X-ray diffraction studies showed a decrease in the crystalline size of compounds that were exposed to gamma irradiation (γ-irradiation). Thermal studies of the synthesized complexes showed thermal stability of the Mn(II) and Pb(II) complexes after γ-irradiation compared to those before γ–irradiation, while no changes in the Zn(II) and Hg(II) complexes were observed. The optimized geometric structures of the ligand and metal complexes are discussed regarding density functional theory calculations (DFT). The antimicrobial activities of the ligand and metal complexes against several bacterial and fungal stains were screened before and after irradiation. The Hg(II) complex has shown excellent antibacterial activity before and after γ-irradiation. In vitro cytotoxicity screening of the ligand and the Mn(II) and Zn(II) complexes before and after γ-irradiation disclosed that both the ligand and Mn(II) complex exhibited higher activity against human liver (Hep-G2) than Zn(II). Molecular docking was performed on the active site of MK-2 and showed good results.

Influences of γ-ray irradiation on physico-chemical, structural, X-ray diffraction, thermal and antimicrobial activity of some γ-irradiated N',N'''-((Z)-ethane-1,2-diylidine)bis(2-aminobenzohydrazide) metal complexes

A series of Co(II), Ni(II), Cu(II), Th(IV) and UO₂(II) complexes have been synthesized from reaction of nitrogen based ligand (L) i.e. N',N'''-((Z)-ethane-1,2-diylidine)bis(2-aminobenzohydrazide)(L) with their salts. Investigation of synthesized metal complexes was achieved by using elemental analyses, magnetic moment, molar conductance, FT-IR, UV/Vis. spectroscopy, thermal techniques and 3D molecular modeling. An octahedral geometry has been suggested for all complexes except for Ni(II) complex (2) which adopted tetrahedral geometry. To through a light on the probability of structure changes with γ-irradiation, the effect of gamma irradiation on powder samples of the complexes [Co(L)Cl₂].4H₂O (1); [Ni₂(L)(OAc)₄].5H₂O (2) and [Cu(L)Br₂].5H₂O (3) was investigated after being exposed to high energetic γ-rays at 100 kGy dose (hereafter referred to as (1A,2A,3A, respectively). Spectral, thermal, magnetic susceptibility, molar conductance and powder X-ray diffraction patterns (XRD) were performed before and after irradiation. In addition, the in vitro antimicrobial activity of the complexes against Staphylococcus aureus as Gram-positive strain, Escherichia coli as Gram-negative strain and antifungal Candida albicans was performed for both unirradiated and irradiated samples. The obtained results showed that the irradiated complexes were affected, but not greatly by the applied γ-irradiation dose.