Synthesis, spectroscopic, thermal properties, Calf thymus DNA binding and quantum chemical studies of M(II) complexes

Determination of Conformational and Functional Stability of Potential Plague Vaccine Candidate in Formulation

Generally, protein-based vaccines are available in liquid form and are highly susceptible to instability under elevated temperature changes including freezing conditions. There is a need to create a convenient formulation of protein/peptides that can be stored at ambient conditions without loss of activity or production of adverse effects. The efficiency of naturally occurring biocompatible polymer dextran in improving the shelf-life and biological activity of a highly thermally unstable plague vaccine candidate protein called Low Calcium Response V antigen (LcrV), which can be stored at room temperature (30 ± 2 °C), has been evaluated. To determine the preferential interactions with molecular-level insight into solvent-protein interactions, analytical techniques such asspectroscopy, particle size distribution, gel electrophoresis, microscopy, and thermal analysis have been performed along with the evaluation of humoral immune response, invivo. The analytical methods demonstrate the structural stability of the LcrV protein by expressing its interaction with the excipients in the formulation. The invivo studies elicited the biological activity of the formulated antigen with a significantly higher humoral immune response (p-value = 0.047) when compared to the native, adjuvanted antigen. We propose dextran as a potential biopolymer with its co-excipient sodium chloride (NaCl) to provide protein compactness, i.e., prevent protein unfolding by molecular crowding or masking mechanism using preferential hydrophobic interaction for up to three weeks at room temperature (30 ± 2 °C).

Density functional theory studies on molecular geometry, spectroscopy, HOMO-LUMO and reactivity descriptors of titanium(IV) and oxidozirconium(IV) complexes of phenylacetohydroxamic acid

The molecular geometry of new titanium(IV) and oxidozirconium(IV) phenylacetohydroxamate complexes [TiCl₂ (L1)₂ ] (I) and [ZrO(L1)₂ ] (II) (where L1 = Potassium phenylacetohydroxamate = C₆ H₅ CH₂ CONHOK) computed by B3LYP/6-311++G(d,p) method has shown these to be distorted octahedral and square pyramidal, respectively. A comparison of computed characteristic bond lengths (CO, CN, and NO) of complexes with that of free ligand has shown chelation through carbonyl and hydroxamic oxygen atoms (O, O coordination). The TiO/ZrO bond lengths in complexes are suggestive of weak coordination through (carbonyl CO) and strong covalent (hydroxamic NO) bonding of the ligand. The magnitude of ClTiCl bond angle involving two chloride atoms is suggestive of cis-conformation at titanium metal in (I). The thermodynamic parameters Gibbs free energy, enthalpy, entropy, nuclear internal energy, constant volume heat capacity, and internal energy of ligand and complexes have been computed. From the energies of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the global reactivity descriptors such as ionization potential (IP), electron affinity (EA), chemical potential (μ), hardness (η), softness (S), electronegativity (χ), electrophilicity index (ω), and dipole moment have been calculated. The computed vibrational frequencies, ¹ H and ¹³ C NMR spectra have substantiated the molecular structure of complexes. The thermal behavior of complexes has been studied by thermogravimetric techniques (TGA, DTG, and DTA) in N₂ atmosphere has shown complexes are thermally stable.

Design and Synthesis of Carbothioamide/Carboxamide-Based Pyrazoline Analogs as Potential Anticancer Agents: Apoptosis, Molecular Docking, ADME Assay, and DNA Binding Studies

To discover anticancer drugs with novel structures and expand our research scope, pyrazoline derivatives (3a-3l) were designed and synthesized through cyclization of chalcones with thiosemicarbazide/semicarbazide in CH₃COOH as a solvent. All newly synthesized pyrazoline derivatives were fully characterized using several spectroscopic experiments such as ¹H, ¹³C NMR, FT-IR spectroscopy, and mass analysis. By HPLC, the purity of all analogs was found above 95% and both lead compounds (3a and 3h) were also validated by HRMS. Anticancer activity of synthesized pyrazoline derivatives (3a-3l) was investigated by the MTT assay against the human lung cancer cell (A549), human cervical cancer cell (HeLa), and human primary normal lung cells (HFL-1). Staurosporine (STS) was used as a standard drug. The anticancer results showed that two potent analogs 3a and 3h exhibit excellent activity against A549 (IC₅₀ = 13.49 ± 0.17 and 22.54 ± 0.25 μM) and HeLa cells (IC₅₀ = 17.52 ± 0.09 and 24.14 ± 0.86 μM) and low toxicity against the HFL-1 (IC₅₀ = 114.50 ± 0.01 and 173.20 ± 10 μM). The flow cytometry was further used to confirm the anticancer activity of potent derivatives against the A549 cancer cell line. DNA binding interaction of anticancer agents 3a and 3h with Ct-DNA has been carried out by absorption, fluorescence, EtBr (dye displacement assay), circular dichroism, cyclic voltammetry and time-resolved fluorescence, which showed noncovalent binding mode of interaction. Anticancer activity of both lead compounds (3a and 3h) may be attributed to DNA binding. The evaluation of the antioxidant potential of pyrazoline analogs 3a and 3h by 2,2-diphenyl-1-picrylhydrazyl free radical showed promising antioxidant activity with IC₅₀ values of 0.132 ± 0.012 and 0.215 ± 0.025 μg/mL, respectively. In silico molecular docking of pyrazoline derivatives was also performed using autodock vina software against the DNA hexamer with PDB ID: 1Z3F and ADMET properties to explore their best hits.

Pyrazoline analogs as potential anticancer agents and their apoptosis, molecular docking, MD simulation, DNA binding and antioxidant studies

N-formyl pyrazoline derivatives (3a-3l) were designed and synthesized via Michael addition reaction through cyclization of chalcones with hydrazine hydrate in presence of formic acid. The structural elucidation of N-formyl pyrazoline derivatives was carried out by various spectroscopic techniques such as ¹H, ¹³C NMR, FT-IR, UV-visible spectroscopy, mass spectrometry and elemental analysis. Anticancer activity of the pyrazoline derivatives (3a-3l) was evaluated against human lung cancer (A549), fibrosarcoma cell lines (HT1080) and human primary normal lung cells (HFL-1) by MTT assay. The results of anticancer activity showed that potent analogs 3b and 3d exhibited promising activity against A549 (IC₅₀ = 12.47 ± 1.08 and 14.46 ± 2.76 µM) and HT1080 (IC₅₀ = 11.40 ± 0.66 and 23.74 ± 13.30 µM) but low toxic against the HFL-1 (IC₅₀ = 116.47 ± 43.38 and 152.36 ± 22.18 µM). The anticancer activity of potent derivatives (3b and 3d) against A549 cancer cell line was further confirmed by flow cytometry based approach. DNA binding interactions of the pyrazoline derivatives 3b and 3d have been carried out with calf thymus DNA (Ct-DNA) using absorption, fluorescence and viscosity measurements, circular dichroism and cyclic voltammetry. Antioxidant potential of N-formyl pyrazoline derivatives (3a-3l) has been also estimated through DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical and H₂O_2. Results revealed that all the compounds exhibited significant antioxidant activity. In silico molecular modelling and ADMET properties of pyrazoline derivatives were also studied using PyRx software against topoisomerase II receptor with PDB ID: 1ZXM to explore their best hits. MD simulation of 3b and 3d was also carried out with topoisomerase II for structure-function correlation in a protein. HuTopoII inhibitory activity of the analogs (3a-3l) was examined by relaxation assay at varying concentrations 100-1000 µM.

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.

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.

Mn(II) complex of a vitamin B6 Schiff base as an exclusive apoptosis inducer in human MCF7 and HepG2 cancer cells: Synthesis, characterization, and biological studies

Herein, a Mn(II) complex of the N,N'-dipyridoxyl(1,4-butanediamine) (═H₂ L) Schiff base has been newly synthesized. The synthesized complex was characterized by several experimental methods. In addition, the density functional theory approaches were used for theoretical identification of the complex. A good agreement between the computed and experimental infrared frequencies demonstrates validity of the optimized geometry for the synthesized complex. In a N₂ O₂ manner, two azomethine nitrogens and two phenolate oxygens of the L^2- ligand are coordinated to the Mn²⁺ metal ion. The biological studies indicate an efficient apoptotic and antioxidant activities of the synthesized [MnL(CH₃ OH)₂ ] complex on both of the HepG2 and MCF7 cancer cells. Since it has been suggested that the complex is an exclusive potent antitumor for treatment of the human breast and liver cancers.

Comment on the frequently used method of the metal complex-DNA binding constant determination from UV-Vis data

Present contribution describes the UV-Vis study of the mixture of Cu(II) ions, pyridoxal 5'-phosphate nicotinoyl hydrazone and DNA. Neither free hydrazone nor its copper(II) complex interacts with DNA under the given concentration conditions. The changes in the UV-Vis spectra of the mixture containing metal complex and DNA are caused by partial dissociation of the coordination compound and complexation of the released Cu(II) ions with DNA. This result was obtained by the analysis of a number of the reactions that could occur in the solution of Cu(II) ions, buffer components (namely, Tris), ligand (hydrazone), and DNA.