Investigation of antileishmanial, antioxidant activities, CT-DNA interaction and DFT study of novel cobalt(II) complexes derived from mesogenic aromatic amino acids based Schiff base ligands

In the present work, new Co(II) complexes were synthesized from mesogenic aromatic amino acids based Schiff base ligands, HL1 [Methyl 2-((2-hydroxy-4-(tetradecyloxy)benzylidene)amino)-3-phenylpropanoate] and HL2 [Methyl 2-((2-hydroxy-4-(tetradecyloxy)benzylidene)amino)-3-(1H-indol-2-yl)propanoate]. The compounds were thoroughly characterised using different elemental, thermogravimetric and spectroscopic studies. The in-vitro antileishmanial efficacy of the compounds against Leishmania donovani was evaluated by MTT assay and the antioxidant activity was performed by Mensor's method. The cell viability percentage and IC50 values for both the antileishmanial and antioxidant studies revealed that the cobalt(II) complexes are comparable to the standard, amphotericin B and ascorbic acid, respectively, signifying the potential applications of the biogenic compounds. The CT-DNA interaction experiments study using photophysical techniques indicated that the cobalt(II) complexes exhibited pronounced interactions as compared to the parent ligand. The parent ligands were found to possess mesogenicity as evidenced from the polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The optical band gap of the compounds, as estimated from the Tauc plot of the UV-Vis spectra, lies within the domain of optoelectronic material properties, which was further supported through Density Functional Theory (DFT) study. Moreover, DFT methods have been used to explore the ground state geometry and DFT based reactivity descriptors of the two synthesised ligands, HL1 and HL2 along with their corresponding Co(II) complexes, Co(L1)2 and Co(L2)2. Reactivity descriptors obtained from Conceptual Density Functional Theory (CDFT) analysis reveal that Co(L1)2 is the most stable and Co(L2)2 is the most electrophilic.

Unlocking the biological potential of transition metal complexes with Thiosemicarbazone ligands: Insights from computational studies

In the previous study, the synthesis and characterization of 4-(3-fluorophenyl)-3-thiosemicarbazide and benzaldehyde derivatives based thiosemicarbazone ligands and their Co(II), Ni(II), Cu(II), Zn(II) complexes were carried out to evaluate their malarial and oxidant and inflammatory inhibition abilities, demonstrating that these compounds have robust efficacy for these ailments. In the present research, to find out a combating agent against breast cancer, tuberculosis, bacterial and fungal ailments, the compounds were tested through MTT, microplate alamar blue and serial dilution protocols. ADMET and DFT investigation were analyzed against highly bioactive compounds (2, 7-10) to give a new insight about compound's reactivity, stability and drug likeness properties. Furthermore, activity results shows that the ligand (2) and its complexes demonstrate greater efficacy compared to ligand (1) and its complexes. The Cu(II) (9) and Zn(II) (10) complexes were observed as highly efficient for breast cancer (MCF-7 cell line), TB (H37Rv strain), bacterial and fungal ailments in comparison of standard drugs with 0.029 ± 0.001 μM IC50 value for (9) in anticancer activity and 0.0034 ± 0.0017 μmol/mL MIC value for (10) in anti-tuberculosis activity. In the molecular docking investigation, the various kind of binding interactions and lowest binding affinity of (9) (against 4RJ3 (-10.0 kcal/mol), 2VCJ (-7.9 kcal/mol)) and (10) (-7.8 and -8.3 kcal/mol for 5V3Y and 3PTY protein) support their bioactivity. This research highlights the pharmaceutical importance of transition metal complexes having thiosemicarbazones, presenting a significant approach for the discovery of potent anti-infectious agent.

Designing, DFT, biological, & molecular docking analysis of new Iron(III) & copper(II) complexes incorporating 1-{[-(2-Hydroxyphenyl)methylene]amino}-5,5-diphenylimidazolidine-2,4-dione (PHNS)

The exploration encompassed the synthesis and characterization of two innovative complexes, namely FePHNS and CuPHNS, employing a diverse array of analytical techniques such as elemental analysis, infrared and ultraviolet-visible spectroscopy, mass spectrometry, molar conductivity measurements, magnetic susceptibility assessments, and thermal analysis (TGA). In the spectral domain, infrared spectroscopy substantiated the tridentate ONS coordination of the PHNS ligand to the central metal atom. Thermal analysis offered valuable insights into the distribution and content of water molecules within the complexes. Density functional theory (DFT) calculations were harnessed to validate the molecular structures of both the PHNS ligand and its complex entities, providing an intricate comprehension of their quantum chemical parameters. The investigation extended to an evaluation of the in vitro antibacterial, antifungal, and antioxidant efficacy of the PHNS ligand and its complexes, revealing heightened biological activities for the complexes in comparison to the free PHNS ligand, notably with the CuPHNS complex demonstrating the highest activity, while the PHNS ligand exhibited the lowest. To delve into potential physiological activities, molecular docking studies were conducted, predicting the binding affinity of the compounds to proteins 2vf5 (Glucosamine-6-phosphate synthase in complex with glucosamine-6-phosphate) from Escherichia coli, 3cku (rate oxidase from Aspergillus flavus complexed with its inhibitor 8-azaxanthin and chloride) from Aspergillus flavus, and 5IJT (Crystal structure of Human Peroxiredoxin 2 Oxidized). The ensuing analysis of protein-ligand interactions and binding energies underscored the promising physiological activities of the investigated compounds, warranting further exploration for their potential in novel drug development.

N'-(Furan-2-ylmethylene)-2-hydroxybenzohydrazide and its metal complexes: synthesis, spectroscopic investigations, DFT calculations and cytotoxicity profiling

The ligand, N'-(furan-2-ylmethylene)-2-hydroxybenzohydrazide (H2L), was synthesized characterized through various spectral studies which cleared out that the free ligand existed in keto form. The ligand upon reaction with Cu(II), Co(II), Ni(II) and Zn(II) acetates yielded complexes with stoichiometric ratio 1:2 (M:L) which has been validated through the elemental and mass spectral measurements. The IR and NMR spectral studies of the isolated complexes disclosed that the ligand chelated to metal ion in mononegative bidentate fashion via the azomethine nitrogen and deprotonated enolized carbonyl oxygen. Moreover, the DFT quantum chemical calculations designated that the ligand and Ni(II) complex exhibited the highest and lowest values of HOMO, LUMO energies and HOMO-LUMO energy gap, respectively. Furthermore, the in vitro cytotoxic activity towards HePG-2 and HCT-116 cell lines of the isolated compounds was investigated and the data cleared out that the ligand was more potent than the metal complexes.

Antifungal activity of Co(II) and Cu(II) complexes containing 1,3-bis(benzotriazol-1-yl)-propan-2-ol on the growth and virulence traits of fluconazole-resistant Candida species: synthesis, DFT calculations, and biological activity

Relevant virulence traits in Candida spp. are associated with dimorphic change and biofilm formation, which became an important target to reduce antifungal resistance. In this work, Co(II) complexes containing a benzotriazole derivative ligand showed a promising capacity of reducing these virulence traits. These complexes exhibited higher antifungal activities than the free ligands against all the Candida albicans and non-albicans strains tested, where compounds 2 and 4 showed minimum inhibitory concentration values between 15.62 and 125 μg mL-1. Moreover, four complexes (2-5) of Co(II) and Cu(II) with benzotriazole ligand were synthesized. These compounds were obtained as air-stable solids and characterized by melting point, thermogravimetric analysis, infrared, Raman and ultraviolet/visible spectroscopy. The analysis of the characterization data allowed us to identify that all the complexes had 1:1 (M:L) stoichiometries. Additionally, Density Functional Theory calculations were carried out for 2 and 3 to propose a probable geometry of both compounds. The conformer Da of 2 was the most stable conformer according to the Energy Decomposition Analysis; while the conformers of 3 have a fluxional behavior in this analysis that did not allow us to determine the most probable conformer. These results provide an important platform for the design of new compounds with antifungal activities and the capacity to attack other target of relevance to reduce antimicrobial resistance.

Investigation of antituberculosis, antimicrobial, anti-inflammatory efficacies of newly synthesized transition metal(II) complexes of hydrazone ligands: structural elucidation and theoretical studies

Tuberculosis disease is a serious threat to humans and spreading quickly worldwide, therefore, to find a potent drug, the synthesis of hydrazone ligands endowed Co(II), Ni(II), Cu(II), Zn(II) metal complexes were carried out and well characterized by numerous spectral and analytical techniques. The octahedral geometry of the complexes was confirmed by spectral analysis. Further, in vitro antituberculosis efficacy of the compounds (1-10) revealed that complexes (6), (9), (10) have highest potency to control TB malformation with 0.0028 ± 0.0013-0.0063 ± 0.0013 µmol/mL MIC value while Zn(II) complex (10) (0.0028 ± 0.0013 µmol/mL) has nearly four time potent to suppress TB disease in comparison of streptomycin (0.0107 ± 0.0011 µmol/mL). The antimicrobial and anti-inflammatory evaluations revealed that the complex (10) is more active with lowest MIC (0.0057-0.0114 µmol/mL) and IC50 (7.14 ± 0.05 µM) values, correspondingly which are comparable with their respective standard drugs. Furthermore, the theoretical studies such as molecular docking, DFT, MESP and ADMET were employed to authenticate the potency of HL2 hydrazone ligand (2) and its metal complexes (7-10) which revealed that the zinc(II) complex (10) might be utilized as novel drug candidate for tuberculosis dysfunctions. So, the present research gives a new insight for in vivo investigation of the compounds.

Thiophene-containing compounds with antimicrobial activity

Thiophene, as a member of the group of five-membered heterocycles containing one heteroatom, is one of the simplest heterocyclic systems. Many synthetic strategies allow the accurate positioning of various functionalities onto the thiophene ring. This review provides a comprehensive, systematic and detailed account of the developments in the field of antimicrobial compounds featuring at least one thiophene ring in their structure, over the last decade.

Recent developments of metal-based compounds against fungal pathogens

This review provides insight into the rapidly expanding field of metal-based antifungal agents. In recent decades, the antibacterial resistance crisis has caused reflection on many aspects of public health where weaknesses in our medicinal arsenal may potentially be present - including in the treatment of fungal infections, particularly in the immunocompromised and those with underlying health conditions where mortality rates can exceed 50%. Combination of organic moieties with known antifungal properties and metal ions can lead to increased bioavailability, uptake and efficacy. Development of such organometallic drugs may alleviate pressure on existing antifungal medications. Prodigious antimicrobial moieties such as azoles, Schiff bases, thiosemicarbazones and others reported herein lend themselves easily to the coordination of a host of metal ions, which can vastly improve the biocidal activity of the parent ligand, thereby extending the library of antifungal drugs available to medical professionals for treatment of an increasing incidence of fungal infections. Overall, this review shows the impressive but somewhat unexploited potential of metal-based compounds to treat fungal infections.

A review: Pharmacological aspects of metal based 1,2,4-triazole derived Schiff bases

Clinical reports have highlighted the radical increase of antibiotic resistance. As a result, multidrug resistance has emerged as a serious threat to human health. Many organic compounds commonly used as drugs in the past, no longer have pure organic mode of action rather need bio-transformation or more activation. Bulk of research has shown that they need trace amount of metal ions incorporated within the chemistry of bioactive molecules for enhancement of their potentiality to fight aggressively against resistance. The deficiency of some metal ions can also be responsible for many diseases like growth retardation, pernicious anemia and heart diseases in infants. To overcome these problems, there is a need to introduce novel strategies which have new mechanism of action along with significant spectrum of biological activity, enhanced safety and efficacy. Bioinorganic compounds have played imperative role in developing the new strategy in the form of "Metal Based Drugs". In current years there have been momentous rise of interest in the application of metal based Schiff base compounds to treat various diseases which are difficult to be treated with conventional methodologies. The unique properties of metal chelates acting as an intermediate between conventional organic and inorganic compounds provided innovative opportunities in the field of pharmaceutical chemistry. In this review, we have exclusively focused on the search of metal based 1,2,4-triazole derived Schiff base compounds (synthesized, reported and reviewed in the past ten years) that possess various biological activities such as antifungal, antibacterial, antioxidant, antidiabetic, anthelmintic, anticancer, antiproliferative, cytotoxic and DNA-intercalation activity.