Synthesis, characterization and in vitro cytotoxicity studies of novel Cu(II) complex containing zonisamide drug: DNA interaction by multi spectroscopic and molecular docking methods

Quantification of mirtazapine in tablets via DNA binding mechanism; development of a new HPLC method

Atypical antidepressant mirtazapine (MIR) is mostly prescribed for the management of major depressive disorder. The identification of MIR in pharmaceutical dosage forms was made possible by developing a novel, quick, sensitive high-performance liquid chromatography (HPLC) approach that was verified in accordance with ICH recommendations. In the first part of this study, HPLC investigations were optimized with regard to variables including pH, working column, mobile phase, temperature, and flow rate. The limit of detection (LOD) was 0.013 ppm, the limit of quantification (LOQ) was 0.044 ppm, and the linear range was computed as 0.5-15 ppm (R2 = 0.9998). The recovery investigation assessed the method's accuracy, which was shown to range between 98.82 and 100.97 %. In the second part, by using UV-vis spectroscopy, HPLC, thermal denaturation, and viscosity measurements, the mechanism of binding interaction of MIR with double-stranded fish sperm deoxyribonucleic acid (dsDNA) has been thoroughly studied. The DNA binding constants (Kb) were determined using UV-Vis absorption and HPLC methods. To investigate the interactions of MIR with dsDNA, molecular docking calculations and additionally, molecular dynamics simulations were performed. Results showed that MIR is located in the minor groove of dsDNA, and in addition to hydrogen bonding, electrostatic interaction is also formed between the aromatic ring of MIR and phosphate oxygen of dsDNA. Finally, a binding characterization study using MIR tablets was also conducted in order to assess the interaction mechanism of the DNA with the drug using the validated analytical procedure developed for the MIR molecule.

Interaction studies of water-soluble Zn(II) complex with calf thymus DNA using biophysical and molecular docking methods"

The binding between a fluorescent water-soluble Zn(II) complex of {2-[N-(2-hydroxyethylammonioethyl) imino methyl] phenol} and calf thymus DNA (ct-DNA) was investigated using spectroscopic techniques. The complex was prepared and identified by FT-IR, and 1H NMR spectroscopies. The significant changes in the absorption and the circular dichroism spectra of ct-DNA in the presence of the Zn(II) complex implied the interaction between the Zn(II) complex and ct-DNA. Upon addition of ct-DNA, the fluorescence emission intensity of the Zn(II) complex was increased and indicated the interaction between the Zn(II) complex and ct-DNA was occurred. The binding constant values (Kb) resulted from fluorescence spectra clearly showed the Zn(II) complex affinity to ct-DNA. The fluorescence studies also approved the static enhancement mechanism in the Zn(II) complex-DNA complexation process. The thermodynamic profile exhibited the exothermic and spontaneous formation of ct-DNA-Zn(II) complex system via hydrogen bonds and van der Waals forces. The competitive fluorescence investigation by methylene blue (MB), and Hoechst 33258 demonstrated that the Zn(II) complex could replace the DNA-bound Hoechst and bind to the minor groove binding site in ct-DNA. The viscosity changes were negligible, representing the Zn(II) complex binding to DNA via the groove binding mode. Molecular docking simulation affirmed that the Zn(II) complex is located in the minor groove of ct-DNA near the DG12, DA17, DA18, and DG16 nucleobases.

DNA interaction studies of a cobalt(III) complex containing β-amino alcohol ligand by spectroscopic and molecular docking methods

In the present research, the feasibility of a Cobalt(III) complex containing β-amino alcohol ligands for affinity with the target calf thymus DNA is demonstrated. In the title complex, [Co(C11H15N2O2)2]Cl, the Co(III) atom is six-coordinated with four N atoms and two O atoms from (2-[(E)-({2-[(2-Hydroxyethyl) amino]ethyl}imino)methyl]phenol) ligand (L). To investigate the molecular interaction between the synthesized complex and DNA, some multi-spectroscopic approaches associated with molecular docking were employed in the physiological buffer (pH 7.4). The results indicated that the Co(III) complex proved to be a minor groove binder with a preference for the A-T region, which was substantiated by displacement studies with Hoechst33258 and Methylene blue (MB) as minor groove binder and intercalator. In addition, the results of the molecular docking study revealed that the Co(III) complex approached the gap between the DNA minor grooves near the spot where the Hoechst was. Furthermore, the results of the cytotoxicity and apoptosis tests for the MCF-7 cell line were also indicative of the positive effects of the complex on controlling the growth and viability of breast cancer.Communicated by Ramaswamy H. Sarma.

Experimental and Molecular Docking Studies on the Interaction of a Water-Soluble Pd(II) Complex Containing β-Amino Alcohol with Calf Thymus DNA

The interaction of water-soluble and fluorescent [Pd (HEAC) Cl₂] complex, in which HEAC is 2-((2-((2-hydroxyethyl)amino)ethyl)amino) cyclohexanol, with calf thymus DNA (ct-DNA) has been studied. This study was performed using electronic absorption and fluorescence emission spectroscopies, cyclic voltammetry and circular dichroism analyses, dynamic viscosity measurements, and molecular docking theory. From hypochromic effect observed in ct-DNA absorption spectra, it was found that the Pd(II) complex could form a conjugate with ct-DNA strands through the groove binding mode. The K_b values obtained from fluorescence measurements clearly assert the Pd(II) complex affinity to ct-DNA. The fluorescence quenching of the DNA-Hoechst compound following the successive additions of the Pd(II) complex to the solution revealed that the Pd(II) complex is located in the ct-DNA grooves, and Hoechst molecules have been released into solution; moreover, the resulting measurements from relative viscosity authenticate the Pd(II) complex binding to the grooves. Negative quantities of thermodynamic parameters imply that the Pd(II) complex binds to ct-DNA mainly by the hydrogen bonds and van der Waals forces; also, the Gibbs-free energy changes show the exothermic and spontaneous formation of the Pd(II) complex-DNA system. The electrochemical behavior of the Pd(II) complex in the attendance of ct-DNA was investigated using the cyclic voltammetry method (CV). Several quasi-reversible redox waves were observed along with increasing the anodic/cathodic peak currents, as well as a shift in anodic/cathodic peak potentials. Circular dichroism (CD) observations suggested that the Pd(II)-DNA interaction could alter ct-DNA conformation. The results of molecular modeling confirmed that groove mechanism is followed by the Pd(II) complex to interact with ct-DNA.

A new electrochemical DNA biosensor for determination of anti-cancer drug chlorambucil based on a polypyrrole/flower-like platinum/NiCo2O4/pencil graphite electrode

In the current study, DNA immobilization was performed on pencil graphite (PG) modified with a polypyrrole (PPy) and flower-like Pt/NiCo₂O₄ (FL-Pt/NiCo₂O₄) nanocomposite, as a new sensitive electrode to detect chlorambucil (CHB). Energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were employed to characterize the synthesized FL-Pt/NiCo₂O₄ and PPy/FL-Pt/NiCo₂O₄ nanocomposites. Moreover, differential pulse voltammetry (DPV) was selected to assess the guanine and adenine electrochemical responses on the DNA sensor. The CHB determination was performed using the maximum currents towards adenine and guanine in the acetate buffer solution (ABS). According to the results, ds-DNA/PPy/FL-Pt/NiCo₂O₄/PGE was able to detect the different concentrations of CHB in the range between 0.018 and 200 μM, with a detection limit of (LOD) of 4.0 nM. The new biosensor was also exploited for CHB determination in real samples (serum, urine and drug), the results of which revealed excellent recoveries (97.5% to 103.8%). Furthermore, the interaction between ds-DNA and CHB was studied using electrochemistry, spectrophotometry and docking whose outputs confirmed their effective interaction.

In the current study, DNA immobilization was performed on pencil graphite (PG) modified with a polypyrrole (PPy) and flower-like Pt/NiCo₂O₄ (FL-Pt/NiCo₂O₄) nanocomposite, as a new sensitive electrode to detect chlorambucil (CHB).

Anti-microbial and anti-cancer activities of Mn0.5Zn0.5DyxFe2-xO4 (x ≤ 0.1) nanoparticles

Combining two or more nanoparticles is a promising approach. Previously we have reported synthesis of nanoparticles Dysprosium (Dy) substituted with manganese (Mn) zinc (Zn) by using ultrasonication method. The five different nanoparticles (NPs) Mn_0.5Zn_0.5Dy_xFe_2-xO₄ (x ≤ 0.1) have been structurally and morphologically characterized but there is no report on the biological application of these NPs. In the present study, we have examined the anti-cancer, anti-bacterial, and anti-fungal activities of Mn_0.5Zn_0.5Dy_xFe_2-xO₄ (x ≤ 0.1) NPs. Human colorectal carcinoma cells (HCT-116) were tested with different concentrations of NPs by using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In addition, the impact of NPs was also examined on normal cells such as human embryonic kidney cells, HEK-293. After 48 h of treatment, Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs (x = 0.02, 0.04 and 0.06) showed no inhibitory action on cancer cell's growth and proliferation, whereas Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs (x = 0.08 and 0.1) showed profound inhibitory action on cancer cell's growth and proliferation. However, the treatment of Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs on the normal cells (HEK-293) did not show cytotoxic or inhibitory action on HEK-293 cells. The treatment of Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs (x ≤ 0.1) also inhibited both the bacteria (Escherichia coli ATCC35218 and Staphylococcus aureus) with lowest MIC and MBC values of 4 and 8 mg/mL and fungus (Candida albicans) with MIC and MFC values of 4 and 8 mg/mL on treatment with x = 0.08 and 0. 1.