Synthesis, DNA/BSA binding studies and in vitro biological assay of nickel(II) complexes incorporating tridentate aroylhydrazone and triphenylphosphine ligands

Evaluation of Iris Kashmiriana Baker plant extracts against nociception and rheumatoid arthritis in experimental rats: A concept proof by In-silico model

ETHNOPHARMACOLOGICAL RELEVANCE

Iris Kashmiriana Baker, a traditional medicinal plant, is native to Asia, found in India, Nepal, Afghanistan, Pakistan, as name indicates majorly it's found in Kashmir region of India. Ethnopharmacologically this plant has been used there for the management of joint pain, but there was no scientific literature available. This species also comes under critically endangered species.

AIM OF THE STUDY

The current study aims to evaluate the effect of Iris kashmiriana Baker against nociception and rheumatoid arthritis in experimental rats with In-silico model.

MATERIAL AND METHODS

Various extracts of the plant were investigated for their in-vitro antioxidant activity. Acute inflammation and FCA induced in rat model, then acetic acid-induced writhing in mice were used. These anti-rheumatic results were justified by the computational method.

RESULTS

The total phenolic and flavonoid concentration of HE extracts were found to be 95.30 ± 2.80 mg/g and 18.18 ± 5.88 mg/g respectively. IC50 and maximum inhibition of HE extracts against DPPH and H2O2 were also effective. Among different doses, 400 mg/kg of HE extracts showed significant (p<0.001) reduction in acute inflammation (16.42 %), in analgesic activity, the HE extract was found statistically (p<0.001) reduced (60.15 %) and in arthritis model, maximum inflammation reduced (25.9%) was found with hydro ethanol extract and statistical significant (p<0.001). and the paw thickness was reduced (27.4 %). Antioxidant activity of HE extract was found to be optimum (37.01%, p<0.001), Superoxide dismutase concentration was found to be optimum (65.12%, p<0.001). In Histopathology, HE 400 mg/kg showed mild inflammation only. The weight of the thymus and spleen were also determined and the HE 400 mg/kg extract inhibited the increase in weight of these organs compared with positive group (28.26 %, and 25.11 %), respectively.

CONCLUSION

Among all the different extracts and various doses, the iris kashmiriana Baker hydro-ethanolic (60:40) 400 mg/kg extract showed the best response among all different extracts.

A multi-spectroscopic and molecular docking approach for DNA/protein binding study and cell viability assay of first-time reported pendent azide bearing Cu(II)-quercetin and dicyanamide bearing Zn(II)-quercetin complexes

In the current study, one new quercetin-based Zn(II) complex [Zn(Qr)(CNNCN)(H2O)2] (Complex 1) which is developed by condensation of quercetin with ZnCl2 in the presence of NaN(CN)2 and Cu(II) complex [Cu(Qr)N3(CH3OH)(H2O)] (complex 2) which is developed by the condensation reaction of quercetin and CuCl2 in presence of NaN3, are thoroughly examined in relation to their use in biomedicine. The results of several spectroscopic studied confirm the structure of both the complexes and the Density Functional Theory (DFT) study helps to optimize the structure of complex 1 and 2. After completion of the identification process, DNA and Human Serum Albumin (HSA) binding efficacy of both the investigated complexes are performed by implementing a long range of biophysical studies and a thorough analysis of the results unveils that complex 1 has better interaction efficacy with the macromolecules than complex 2. The binding efficacy of complex 1 is comparatively higher towards both macromolecules because of its pure groove binding mode during interaction with DNA and the presence of an extra H-bond during connection with HSA. The experimental host-guest binding results is fully validated by molecular docking study. Interestingly complex 1 shows better antioxidant properties than complex 2, as well as quercetin, and it has strong anticancer property with minimal damage to normal cells, which is proved by the MTT assay study. Better DNA and HSA binding efficacy of 1 may be the reason for the better anticancer property of complex 1.

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.

Oxoperoxovanadium Complexes of Hetero Ligands: X-Ray Crystal Structure, Density Functional Theory, and Investigations on DNA/BSA Interactions, Cytotoxic, and Molecular Docking Studies

Oxoperoxovanadium (V) complexes [VO (O)₂ (nf) (bp)] (1) and [VO (O)₂ (ox) (bp)] (2) based on 5-nitro-2-furoic acid (nf), oxine (ox) and 2, 2′ bipyridine (bp) bidentate ligands have been synthesized and characterized by FT-IR, UV-visible, mass, and NMR spectroscopic techniques. The structure of complex 2 shows distorted pentagonal-bipyramidal geometry, as confirmed by a single-crystal XRD diffraction study. The interactions of complexes with bovine serum albumin (BSA) and calf thymus DNA (CT-DNA) are investigated using UV-visible and fluorescence spectroscopic techniques. It has been observed that CT-DNA interacts with complexes through groove binding mode and the binding constants for complexes 1 and 2 are 8.7 × 10³ M⁻¹ and 8.6 × 10³ M⁻¹, respectively, and BSA quenching constants for complexes 1 and 2 are 0.0628 × 10⁶ M⁻¹ and 0.0163 × 10⁶ M⁻¹, respectively. The ability of complexes to cleave DNA is investigated using the gel electrophoresis method with pBR322 plasmid DNA. Furthermore, the cytotoxic effect of the complexes is evaluated against the HeLa cell line using an MTT assay. The complexes are subjected to density functional theory calculations to gain insight into their molecular geometries and are in accordance with the results of docking studies. Furthermore, based on molecular docking studies, the intermolecular interactions responsible for the stronger binding affinities between metal complexes and DNA are discussed.

Synthesis, characterisation, DNA binding, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities and molecular docking studies of metal(II) complexes with 1,10-phenanthroline scaffold

A series of metal complexes containing Phenanthroline scaffold [ML] (L-1,10-Phenanthroline derivative comprises conjugated aromatic core and selenol group); M = Cu(II), Zn(II), Co(II) and Zn(II) ions were designed and synthesised to obtain effective anti-cholinesterase efficiencies of metal chelates. Analytical and spectroscopic studies were used to determine the structural features. An octahedral structure with moderate distortion was attributed to the above metal chelates based on spectroscopic data. The distorted octahedral geometry of copper(II) complex to DNA (K_b = 4.05 × 10⁵ M^-1) is stronger than that of ethidium bromide (EB) to DNA (K_b = 3.2 × 10⁵ M^-1), other metal complexes, respectively. The synthesised 1,10-Phenanthroline derivative had the best inhibitory effects against acetylcholinesterase (AChE) and butyrylcholinesterase, with IC₅₀ values of 0.45 and 3.6 M, respectively, which were lower than the reference molecules. As a result, nitrogen-containing heterocyclic compounds (H₂L) showed significant inhibitory profiles against the metabolic enzymes. Therefore, we believe that these experimental results may contribute to the development of new drug molecules particularly in the treatment of neurological disorders including glaucoma, Alzheimer's disease (AD) and diabetes. Docking, AChE and BuChE inhibition activities results revealed that ligand may be used for AD. The prepared 1,10-phenanthroline analogue, which has a high selectivity for AChE, may be studied further to find potential candidates for treating early-stage Alzheimer's symptoms.Communicated by Ramaswamy H. Sarma.

Synthesis, characterization of ruthenium(II), nickel(II), palladium(II), and platinum(II) triphenylphosphine-based complexes bearing an ONS-donor chelating agent: Interaction with biomolecules, antioxidant, in vitro cytotoxic, apoptotic activity and cell cycle analysis

Four new transition metal complexes, [M(PPh₃)(L)]^.CH₃OH (M = Ni(II) (1), Pd(II) (2)) [Pt (PPh₃)₂(HL)]Cl (3) and [Ru(CO)(PPh₃)₂(L)] (4) (H₂L = 2,4-dihydroxybenzaldehyde-S-methyldithiocarbazate, PPh₃ = triphenylphosphine) have been synthesized and characterized by elemental analyses (C, H, N), FTIR, NMR (¹H, ³¹P), ESI-MS and UV-visible spectroscopy. The molecular structure of (1) and (2) complexes was confirmed by single-crystal X-ray crystallography. It showed a distorted square planar geometry for both complexes around the metal center, and the H₂L adopt a bi-negative tridentate chelating mode. The interaction with biomolecules viz., calf thymus DNA (ct DNA), yeast RNA (tRNA), and BSA (bovine serum albumin) was examined by both UV-visible and fluorescence spectroscopies. The antioxidant activity of all compounds is discussed on basis of DPPH^• (2,2-diphenyl-1-picrylhydrazyl) scavenging activity and showed better antioxidant activity for complexes compared to the ligand. The in vitro cytotoxicity of the compounds was tested on human (breast cancer (MCF7), colon cancer (HCT116), liver cancer (HepG2), and normal lung fibroblast (WI38)) cell lines, showing that complex (1) the most potent against MCF7 and complex (4) against HCT116 cell lines based on IC₅₀ and selective indices (SI) values. So, both complexes were chosen for further studies such as DNA fragmentation, cell apoptosis, and cell cycle analyses. Complex (1) induced MCF7 cell death by cellular apoptosis and arrest cells at S phase. Complex (4) induced HCT116 cell death predominantly by cellular necrosis and arrested cell division at G2/M phase due to DNA damage.

Antitumor activity of tridentate pincer and related metal complexes

Pincer complexes featuring tunable tridentate ligand frameworks are one of the most actively studied classes of metal-based complexes. Currently, growing attention is devoted to the cytotoxicity of pincer and related metal complexes. The antiproliferative activity of numerous pincer complexes has been reported. Pincer tridentate ligand scaffolds show different coordination modes and offer multiple options for directed structural modifications. This review summarizes the significant progress in the research studies of the antitumor activity of pincer and related platinum(ii), gold(iii), palladium(ii), copper(ii), iron(iii), ruthenium(ii), nickel(ii) and some other metal complexes, in order to provide a reference for designing novel metal coordination drug candidates with promising antitumor activity.

Syntheses, crystal structures of two Fe(III) Schiff base complexes with chelating o-vanillin aroylhydrazone and exploration of their bio-relevant activities

Two novel Fe(III) complexes, Fe(HL¹)₂Cl·1.25H₂O (1) and Fe(HL²)₂·Et₃NH·H₂O (2) (H₂L¹ = o-vanillin benzoylhydrazone, H₃L² = o-vanillin salicylhydrazone) are prepared. X-ray single crystal diffraction confirms that the hydrazone ligands can be chelated to iron centre resulting in a six-coordinate octahedral configuration. Both complexes show major intercalation effect to the herring sperm deoxyribonucleic acid (HS-DNA) with high binding constants of 2.01 × 10⁴ M^-1 and 2.24 × 10⁴ M^-1, respectively. Molecular docking studies reveal both complexes can intercalate at the gap of DC5-DG2 and DG6-DC1 base pairs of DNA hexamer (1Z3F). The interaction of the complex 1 with plasmid pBR322 DNA induces distinguishable alterations of the DNA morphology. Further, the structure of plasmid pBR322 DNA treated with complex 1 in the presence of ascorbic acid has been damaged probably due to the reactive oxygen species (ROS) generation. What's more, both complexes show high affinity with bovine serum albumin (BSA), the binding constants measured by fluorescence techniques are 5.75 × 10⁶ M^-1 and 4.39 × 10⁷ M^-1, respectively. Molecular docking demonstrates that the complexes prefer the binding pocket of site III (subdomain IIB) of BSA (PDB ID: 4F5S). Similarly, dynamic light scattering (DLS) reveals that the complexes not only bind to BSA but also induce bigger size aggregates as the concentration increases.

Synthesis, crystal structure, Hirshfeld surface analysis, DNA binding, DNA cleavage activity and molecular docking of a new Schiff base nickel(II) complex

A mononuclear nickel(II) complex, [Ni(o-van-tris)₂]·2H₂O (o-van-tris = Schiff base derived from o-vanillin and tris(hydroxymethyl)aminomethane), has been synthesized and structurally characterized. The single crystal structure shows a distorted octahedron geometry coordinated with Ni(II) atom, and 2 D plane structure has formed by O-H···O hydrogen bond interactions. An analysis to ascertain intermolecular interactions of the complex was performed based on the Hirshfeld surfaces and their associated two-dimensional fingerprint plots. The binding properties of the nickel(II) complex with CT-DNA have been investigated by spectroscopic methods and molecular docking. Absorption and fluorescence spectral studies reveal that the complex interacts with DNA through hydrogen bond and hydrophobic interactions with the DNA base pairs. Molecular docking studies show that the complex effectively docks in the major groove of DNA. The DNA cleavage experiment was performed by gel electrophoretic assay, indicating that DNA cleavage activity of the complex is concentration dependent and much sensitive to ionic strength. The efficient cleavage mediated via hydrolytically cleaving pathway.Communicated by Ramaswamy H. Sarma.

Protein binding and antioxidant studies of diimine based emissive surfactant-ruthenium(II) complexes

Biophysical interaction of amphiphilic fluorescent surfactant-ruthenium(II) complexes and its precursor ruthenium(II) complexes with drug carrying proteins such as bovine and human serum albumins (BSA and HSA) have been studied through the UV-visible absorption, fluorescence and circular dichroism spectroscopic techniques to correlate the impact of head and tail groups of the metallosurfactants towards the designing of metallodrugs for the biomedical applications. The obtained results showed that both precursor- and surfactant-ruthenium(II) complexes interact with BSA/HSA via ground state protein-complex formation and their quenching follows the static mechanism. The extent of protein quenching and binding parameters resulted that the surfactant-ruthenium(II) complexes effectively interact with protein compared to their precursor-ruthenium(II) complexes, and also those interaction have greatly influenced by the change in the head group size compared to change in the tail group length. Interestingly on increasing the temperature, the protein-complex binding strength was decreased for the precursor-ruthenium(II) complexes, those increased for the surfactant-ruthenium(II) complexes, probably due to the respective involvement of electrostatic and hydrophobic interactions as supported by the thermodynamics of protein-complex interaction. Moreover, the results from UV-visible, synchronous and circular dichroism studies confirmed the occurrence of conformational and micro environmental changes in BSA/HSA upon binding with these complexes. It is also noted that HSA has more binding affinity with surfactant-ruthenium(II) complexes compared to BSA. The free radical scavenging ability against DPPH, ABTS, NO and superoxide free radical assays suggested that surfactant-ruthenium(II) complexes have better free radical scavenging ability compared to precursor-ruthenium(II) complexes.Communicated by Ramaswamy H. Sarma.