Design, synthesis, antioxidant, antimicrobial, DNA binding and molecular docking studies of morpholine based Schiff base ligand and its metal(II) complexes

Fabrication of CuNPs Using Schiff Base Ligand and Their Catalytic Reduction of Pharmaceutical Drugs, Fluorescence Selective Detection of Cd2+, Antimicrobial, and Antioxidant Activities

Here, we have approached the synthesis of copper nanoparticles (CuNPs) Schiff base (5-trifluoromethoxy-2-(((2chloro-5-(methyl)phenyl)imino)methyl)phenol)). The synthesized CuNPs were characterized by UV-vis spectroscopy, PL, FTIR, powder XRD, and TEM analysis. From the UV-vis absorption spectroscopy, an absorption peak was observed at 585 nm. As a result of the powder XRD and TEM studies, spherical particle sizes ranged between 4 and 10 nm. FT-IR analysis confirmed the presence of functional groups ‒OH, C=C, -C=N-, and C‒H triggers the synthesis of CuNPs. Further, the catalytic property of the CuNPs were revealed by the degradation of pharmaceutical drugs such as Capecitabine (CAP) and Ciprofloxacin (CIP) in 90 min of reaction time in the presence of NaBH4. The reaction kinetics followed pseudo-first-order with k-values (rate constant) 0.248 min-1 and 0.307 min-1. In addition, the synthesized CuNPs have exhibited selective sensing detection of Cd2+ metal ions in different range of concentration (10-100 µM) by spectrofluorometrically with the limit of detection (LOD) is 0.0284 nM and limit of quantification (LOQ) is 0.0586 nM. The CuNPs revealed significant antioxidant activities against DPPH as a common free radical at 50 µg/mL with 71.24% of scavenging activity. The maximum antimicrobial potential and zone of inhibition of P. Aeruginosa is 17.25±0.8 mm and A. niger is 12.1 mm by using CuNPs.

Spectroscopic and theoretical approach of DNA interaction and anticancer studies of bio-pharmaceutically active pyrimidine derived Cu(II) and Zn(II) complexes

New metal(II) complexes (CuL2 and ZnL2) with pyrimidine appended Schiff base ligand (HL) were synthesized and characterized by diverse spectroscopic methods, reveals the proposed structure of metal(II) complexes possess square planar geometry. DNA interaction ability of isolated compounds was studied by UV-Visible, fluorescence, viscometric and electrochemical methods and the results showed that isolated compounds intercalated with calf thymus DNA (CT-DNA). In addition, anticancer activities of HL, CuL2, and ZnL2 have been evaluated by MTT assay, signifying moderate cytotoxic activity on selected cancer cell lines and less toxicity on NHDF normal cell line due to the specific targeting of pyrimidine analogues. Moreover, antioxidant activities of isolated compounds towards diverse free radicals have been studied by spectrophotometric methods. These results showed that CuL2 has better antioxidant ability than HL and ZnL2. Finally, antimicrobial activities of isolated compounds against selected antimicrobial pathogens exposed that CuL2 has better antimicrobial activity on E. coli and C. albicans than other antimicrobial pathogens. The DFT calculations have been done to get the optimized geometry of the ligand and the metal complexes. In order to get a broad understanding of the interactions of these synthesized metal complexes, a detailed molecular docking analysis is taken up.

Synthesis, spectral characterization, computational studies, antifungal, DNA interaction, antioxidant and fluorescence property of novel Schiff base ligand and its metal chelates

Cobalt, Copper, Nickel and Zinc coordinated metal complexes were synthesized by novel thiazole Schiff base ligand 2-ethoxy-4-((5-methylthiazol-2-ylimino)methyl) phenol derived from 3-ethoxy-4-hydroxybenzaldehyde and 2-amino- 5-methylthiazol. The synthesized compounds were spectrochemically characterized by elemental analysis, molar conductance, FT-IR, UV-Vis, Mass spectral analysis, Powdered-XRD and cyclic voltammetry. The thermal stability of synthesized complexes were investigated by using thermogravimetric analysis (TGA). Theoretical computational study were performed for all the synthesized compounds utilizing the DFT/B3LYP method at the 6-31G basic set for Schiff base ligand whereas LANL2DZ basis set for metal complexes. Molecular Electrostatic Potential (MEP), HOMO-LUMO, Mulliken charges and global reactivity descriptors, including chemical potential (μ), global softness (S), chemical hardness (η), and electrophilicity index (ω) were measured and correlated with antimicrobial activity. The synthesized thiazole Schiff base ligand and its coordinated metal complexes shows good antifungal agreement against Fusarium Oxysporum and Aspergillus Niger species. These compounds also exhibit DNA binding, DNA cleaving and antioxidant activity. All the synthesized molecules indicate potential fluorescence property.

Recent advances of benzimidazole as anticancer agents

Cancer is the second leading cause of death globally, with 9.6 million deaths yearly. As a life-threatening disease, it necessitates the emergence of new therapies. Resistance to current chemotherapies drives scientists to develop new medications that will eventually be accessible. Because heterocycles are so common in biological substances, compounds play a big part in the variety of medications that have been developed. The "Master Key" is the benzimidazole nucleus, which consists of a six-membered benzene ring fused with a five-membered imidazole/imidazoline ring, which is an azapyrrole. One of the five-membered aromatic nitrogen heterocycles identified in American therapies that have been approved by the Food and Drug Administration (FDA). Our results show that benzimidazole's broad therapeutic spectrum is due to its structural isosteres with purine, which improves hydrogen bonding, electrostatic interactions with topoisomerase complexes, intercalation with DNA, and other functions. It also enhances protein and nucleic acid inhibition, tubulin microtubule degeneration, apoptosis, DNA fragmentation, and other functions. Additionally, readers for designing the more recent benzimidazole analogues as prospective cancer treatments.

Biologically active oxovanadium(IV) Schiff base metal complex: antibacterial, antioxidant, biomolecular interaction and molecular docking studies

The oxovanadium(IV) Schiff base metal complex (ISNPV) have been synthesized as well as characterized by using micro analytical and traditional spectroscopic techniques. The spectral findings were utilized to validate the formation of ISNPV with structure exhibited square pyramidal geometry. The in vitro antibacterial activities of ISNPV were investigated to five different bacterial stains such as S. aureus, S. epidermidis, B. cereus, B. amyloliquefaciens and B. subtilis. The obtained result have suggested that the ISNPV has highest antibacterial activity against S. aureus than the other bacterial stains. The in vitro antioxidant activity like DPPH free radical scavenging assay method was studied by ISNPV in DMSO medium. Because it scavenges all free radicals, the ISNPV possesses higher antioxidant activity than the free ligand. UV-visible absorption and emission spectral techniques were used to investigate the binding of CT-DNA to the ISNPV. Both the spectral data indicate that the ISNPV binds the double helix structure of CT-DNA via an intercalation mode. Additionally, investigate the interactions of ISNPV with the protein molecules like BSA/HAS has been investigated using absorption and emission techniques. The absorption intensity of metal complex increases as well as the emission intensity of protein molecules ability decreases due to the binding nature of ISNPV with BSA/HSA protein molecules. The binding nature of ISNPV with bio molecules such as CT-DNA, BSA and HSA was also validated using molecular docking approach.

Bio-inspired nickel nanoparticles of pyrimidine-Schiff base: In vitro anticancer, BSA and DNA interactions, molecular docking and antioxidant studies

In this work, interactions of pyrimidine derivative Schiff base ligand (DMPMM) were studied and its stabilized powder nickel nanoparticles (DMPMM-NiNPs) were synthesized and various biological studies were evaluated. DNA binding studies of CT-DNA with prepared compounds in Tris-HCl/NaCl buffer were carried out by traditional UV-Visible and fluorescence spectroscopic methods, viscosity measurements and cyclic voltammetry. Results showed that the small scale of DMPMM had less activity to interact with biological systems and when it assembled on nickel nanoparticles surface the activity increased. Thermal denaturation and sonochemical denaturation studies of DNA with the presence and the absence of our compounds also were done by UV-Visible spectroscopic method and its results indicated that the synthesized compounds increased the denaturation temperature. BSA binding studies of synthesized compounds were done by UV-Visible and fluorescence spectroscopy. Molecular docking of prepared ligand and its nanoparticles with biomolecules (DNA and BSA) were studied. Antimicrobial studies of the DMPMM and DMPMM-NiNPs were carried out by Agar-Agar well diffusion method. Anticancer studies results evidenced that the synthesized DMPMM-NiNPs had good selectivity to control the growth of cancer cells without damaging the normal cells. Various antioxidant scavenging studies results have shown that DMPMM and DMPMM-NiNPs have significant antioxidant activity. HighlightsStable and solid nickel nanoparticles were prepared.The size of the prepared nickel nanoparticles was nearly 3 to 8 nm.Organic ligand capped nickel nanoparticles interacted with DNA and BSA.Ni nanoparticles increased the denaturation temperature of DNA.It was found to have good anticancer activity with fewer side effects than cisplatin.Communicated by Ramaswamy H. Sarma.

Synthesis, characterization, antioxidant and anticancer activities of a new Schiff base and its M(II) complexes derived from 5-fluorouracil

In this study, Schiff base ligand was obtained from the condensation reaction of benzene-1,2-diamine and 5-fluoropyrimidine-2,4(1H,3H)-dione (5-FU). Metal(II) complexes were synthesized with Fe(II), Co(II) and Ni(II) chloride salts. The synthesized ligand and metal complexes were characterized by FT-IR, UV-vis, ¹H-¹³C NMR, elemental analyses, mass spectroscopy, magnetic moments, molar conductivity and thermogravimetric analysis studies. With the help of different techniques reveal Fe(II), Co(II) and Ni(II) complexes have exhibited tetrahedral and octahedral geometry. Ligand acted as bidentate and it binds metal(II) ions through deprotonated-NH, imine-N atom and carbonyl-O atom, respectively. DPPH, ABTS, FRAP, CUPRAC and total antioxidant activity methods were used to determine the antioxidant properties of ligand and metal complexes. According to the results, the synthesized compounds showed very high antioxidant activity compared to 5-FU. The cytotoxicities of the synthesized compounds were performed on MCF-7 (human breast cancer) and L-929 (fibroblast) cell lines using the MTT assay. In addition, the effect of electroporation (EP) on the cytotoxicity of the compounds was investigated. Our results demonstrated that novel Co(II) and Ni(II) complexes show potential as new anticancer agents and ECT may be a viable treatment option for breast cancer.

Dithiocarbazate Ligand-Based Cu(II), Ni(II), and Zn(II) Complexes: Synthesis, Structural Investigations, Cytotoxicity, DNA Binding, and Molecular Docking Studies

S-4-methylbenzyl-β-N-(2-methoxybenzylmethylene)dithiocarbazate ligand, 1, prepared from S-(4-methylbenzyl)dithiocarbazate, was used to produce a novel series of transition metal complexes of the type, [M (L)₂] [M = Cu(II) (2), Ni(II) (3), and Zn(II) (4), L = 1]. The ligand and its complexes were investigated by elemental analysis, FTIR, ¹H and ¹³C-NMR, MS spectrometry, and molar conductivity. In addition, single X-ray crystallography was also performed for ligand, 1, and complex 3. The Hirshfeld surface analyses were also performed to know about various bonding interactions in the ligand, 1, and complex 3. The investigated compounds were also tested to evaluate their cytotoxic behaviour. However, complex 2 showed promising results against MCF-7 and MDA-MB-213 cancer cell lines. Furthermore, the interaction of CT-DNA with ligand, 1, and complex 2 was also studied using the electronic absorption method, revealing that the compounds have potential DNA-binding ability via hydrogen bonding and hydrophobic and van der Waals interactions. A molecular docking study of complex 2 was also carried out, which revealed that free binding free energy value was −7.39 kcal mol⁻¹.

Spectrophotometric and fluorometric detection of DNA/BSA interaction, antimicrobial, anticancer, antioxidant and catalytic activities of biologically active methoxy substituted pyrimidine-ligand capped copper nanoparticles

New Schiff base ligand (DPMN) was synthesized from the condensation of 2-hydroxy-5-nitrobenzaldehyde and 2-amino-4,6-dimethoxypyrimidine which was confirmed by spectroscopic and analytical methods. Solid air stable copper nanoparticles (DPMN-CuNPs) were synthesized from its copper chloride salt and it is stabilized by the prepared Schiff base ligand by phase transfer assisted synthesis which is a modified Brust-Schiffrin technique. The formation of ligand stabilized copper nanoparticles was confirmed by UV-Visible and FT-IR spectroscopic techniques. The size, surface morphology and quality of DPMN-CuNPs were analyzed by SEM and TEM techniques. Antioxidant activities of DPMN and DPMN-CuNPs with DPPH, SOD, peroxide and nitrous oxide were analyzed by electronic absorption spectroscopy. DNA interaction between DPMN and DPMN-CuNPs with CT-DNA was carried out using electronic absorption, fluorescence, viscometric measurements and cyclic voltammetric techniques. Interaction between BSA and the synthesized compounds analyzed by electronic absorption spectroscopy, Antimicrobial studies confirmed that the synthesized DPMN-CuNPs possess significant biological activities than DPMN. Anticancer results suggest that prepared DPMN-CuNPs have significant anticancer activity against different cancer cell lines and least toxic effect against the normal (NHDF) cell line. Other than the positive response in biological evaluation, our DPMN-CuNPs possess good catalytic activity in methyl orange reduction, methylene blue degradation and nitro phenol reduction.

In Vitro Evaluation of the Potential Pharmacological Activity and Molecular Targets of New Benzimidazole-Based Schiff Base Metal Complexes

Metal-based drugs, including lanthanide complexes, have been extremely effective in clinical treatments against various diseases and have raised major interest in recent decades. Hence, in this work, a series of lanthanum (III) and cerium (III) complexes, including Schiff base ligands derived from (1H-benzimidazol-2-yl)aniline, salicylaldehyde, and 2,4-dihydroxybenzaldehyde were synthesized and characterized using different spectroscopic methods. Besides their cytotoxic activities, they were examined in human U-937 cells, primate kidney non-cancerous COS-7, and six other, different human tumor cell lines: U251, PC-3, K562, HCT-15, MCF-7, and SK-LU-1. In addition, the synthesized compounds were screened for in vitro antiparasitic activity against Leishmania braziliensis, Plasmodium falciparum, and Trypanosoma cruzi. Additionally, antibacterial activities were examined against two Gram-positive strains (S. aureus ATCC® 25923, L. monocytogenes ATCC® 19115) and two Gram-negative strains (E. coli ATCC® 25922, P. aeruginosa ATCC® 27583) using the microdilution method. The lanthanide complexes generally exhibited increased biological activity compared with the free Schiff base ligands. Interactions between the tested compounds and model membranes were examined using differential scanning calorimetry (DSC), and interactions with calf thymus DNA (CT-DNA) were investigated by ultraviolet (UV) absorption. Molecular docking studies were performed using leishmanin (1LML), cruzain (4PI3), P. falciparum alpha-tubulin (GenBank sequence CAA34101 [453 aa]), and S.aureus penicillin-binding protein 2a (PBP2A; 5M18) as the protein receptors. The results lead to the conclusion that the synthesized compounds exhibited a notable effect on model membranes imitating mammalian and bacterial membranes and rolled along DNA strands through groove interactions. Interactions between the compounds and studied receptors depended primarily on ligand structures in the molecular docking study.

Bioactive platinum complex of ligand bearing pyrimidine skeleton: DNA/BSA binding, molecular docking, anticancer, antioxidant and antimicrobial activities

A new octahedral platinum complex [PtLCl₄] of Schiff base ligand containing pyrimidine and morpholine skeleton (where, L is 4,6-dichloropyrimidin-5-yl)methylene)-2-morpholinoethanamine) was isolated and characterized by elemental analysis, ¹H-NMR, FTIR, UV-visible and ESI-MS techniques. DNA interaction of isolated compounds with calf thymus (CT-DNA) was explored by UV-vis absorption, fluorescence, cyclic voltametric and viscometric methods. The result shows that prepared compounds can interact with CT-DNA through electrostatic interactions. Bovine serum album (BSA) binding behavior of isolated compounds was also studied by UV-vis absorption and fluorescence techniques. Both the spectroscopic results suggest that the isolated ligand and its complex bind with BSA through static quenching. The optimized structure of ligand and platinum complex were achieved by the DFT calculations. Moreover, molecular docking of ligand and its complex were studied. These analysis results reveal that ligand has low binding affinity on DNA and BSA molecules in contrast to its complex. In vitro anticancer activity of isolated compounds toward normal cell line (NHDF) as well as cancer cell lines (MCF-7, HepG2, HeLa and A549) was studied by MTT assay. The results supports that isolated platinum complex can control the growth of cancer cells (MCF-7, 20.12 ± 1.00 µg/mL; HepG2, 32.2 ± 1.69 µg/mL; HeLa, 24.68 ± 1.29 µg/mL; A549, 23.46 ± 1.17 µg/mL) without inhibiting the normal cell line (NHDF, 109.26 ± 5.46 µg/mL). Antioxidant and antimicrobial activities of isolated compounds indicate that ligand and Pt complex are found to have good radical scavenging against four different free radicals and antimicrobial abilities on E. coli and C. albicans antimicrobial species. HighlightsPlatinum complex of Schiff base with pyrimidine and morpholine linkage was synthesized.Pt complex has better biomolecular interaction with DNA and BSA.Molecular docking of Pt complex with DNA and BSA has been studiedPt complex has good anticancer activities.Pt complex has better antioxidant and antimicrobial activities.