DNA interaction studies of a novel Cu(II) complex as an intercalator containing curcumin and bathophenanthroline ligands

Spectroscopic and molecular modeling study on the separate and simultaneous bindings of alprazolam and fluoxetine hydrochloride to human serum albumin (HSA): with the aim of the drug interactions probing

The objective of the present research is to study the interaction of separate and simultaneous of alprazolam (ALP) and fluoxetine hydrochloride (FLX) with human serum albumin (HSA) in phosphate buffer (pH 7.4) using different kinds of spectroscopic, cyclic voltammetry and molecular modeling techniques. The absorbance spectra of protein, drugs and protein-drug showed complex formation between the drugs and HSA. Fluorescence analysis demonstrated that ALP and FLX could quench the fluorescence spectrum of HSA and demonstrated the conformational change of HSA in the presence of both drugs. Also, fluorescence quenching mechanism of HSA-drug complexes both separately and simultaneously was suggested as static quenching. The analysis of UV absorption data and the fluorescence quenching of HSA in the binary and ternary systems showed that FLX decreased the binding affinity between ALP and HSA. On the contrary, ALP increased the binding affinity of FLX and HSA. The results of synchronous fluorescence and three-dimensional fluorescence spectra indicated that the binding of drugs to HSA would modify the microenvironment around the Trp and Tyr residues and the conformation of HSA. The distances between Trp residue and the binding sites of the drugs were estimated according to the Förster theory, and it was demonstrated that non-radiative energy transfer from HSA to the drugs occurred with a high probability. Moreover, according to CV measurements, the decrease of peak current in the cyclic voltammogram of the both drugs in the presence of HSA revealed that they interacted with albumin and binding constants were calculated for binary systems which were in agreement with the binding constants obtained from UV absorption and fluorescence spectroscopy. The prediction of the best binding sites of ALP and FLX in binary and ternary systems in molecular modeling approach was done using of Gibbs free energy.

Zn(ii) and Cu(ii) complexes containing bioactive O,O-chelated ligands: homoleptic and heteroleptic metal-based biomolecules

Zn(ii) or Cu(ii) highly stable complexes with chelated O,O-donor ligands from natural extractions give rise to drug delivery systems, new biologically active complexes and potential diagnostic agents due to their intrinsic spectroscopic properties.

Partial intercalative binding of the food colorant erythrosine to herring sperm DNA

Erythrosine partially inserts into the G–C rich region of hsDNA and induces moderate conformational perturbation of the DNA.

Metal based pharmacologically active complexes of Cu(II), Ni(II) and Zn(II): synthesis, spectral, XRD, antimicrobial screening, DNA interaction and cleavage investigation

The present contribution reports a thorough characterization of newly obtained metallointercalators incorporating Schiff bases, formed by the condensation of N-acetoacetyl-o-toluidine with 1-amino-4-nitrobenzene (L(1))/1-amino-4-chlorobenzene (L(2)) as main ligand and 1,10-phenanthroline as co-ligand respectively. The characterization of newly formed metallointercalators has been done by (1)H NMR, UV-Vis, IR, EPR spectroscopy and molar conductivity studies. X-ray powder diffraction illustrates that they are crystalline nature. Binding interaction of these complexes with calf thymus (CT-DNA) has been investigated by emission, absorption, viscosity, cyclic voltammetry and differential pulse voltammetry. DNA binding experiments results reveal that the synthesized complexes interact with DNA through intercalative mode. The in vitro antibacterial and antifungal assay indicate that these complexes are good antimicrobial agents against various pathogens. The DNA cleavage exhibits that they act as efficient cleaving agents.

Lasing the DNA fragments through β-diketimine framed Knoevenagel condensed Cu(II) and Zn(II) complexes--an in vitro and in vivo approach

The syntheses, structures and spectroscopic properties of Cu(II) and Zn(II) complexes having Knoevenagel condensate β-diketimine Schiff base ligands have been investigated in this paper. Characterization of these complexes was carried out using FTIR, NMR, UV-Vis, elemental analysis, mass and EPR techniques. Absorption titration, electrochemical analyses and viscosity measurements have also been carried out to determine the mode of binding. The shift in ΔEp, E1/2 and Ipc values explores the interaction of CT DNA with the above metal complexes. Interaction of ligands and their complexes with DNA revealed an intercalative mode of binding between them. Antimicrobial studies showed an effective antimicrobial activity of the metal ions after coordination with the ligands. The antioxidant properties of the Schiff base ligands and their complexes were evaluated in a series of in vitro tests by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and H2O2 free radical scavengers. In vivo and in vitro antitumor functions of the complexes against Ehrlich ascites carcinoma tumor model have also been investigated. All the results support that β-diketone derived Knoevenagel condensate Schiff base complexes may act as novel antitumor drugs and suggest that their potent cell life inhibition may contribute to their anti-cancer efficacy.

Homologous 1,3,5-triarylpyrazolines: synthesis, CH⋯π interactions guided self-assembly and effect of alkyloxy chain length on DNA binding properties

The synthesis, CH⋯π interactions-driven self-assembled structure and DNA binding properties (10⁵–10⁶M⁻¹binding constants) of new homologous 1,3,5-triaryl-2-pyrazolines are reported.

Indicine N-oxide binds to tubulin at a distinct site and inhibits the assembly of microtubules: a mechanism for its cytotoxic activity

Indicine N-oxide, a pyrrolizidine alkaloid present in the plant Heliotropium indicum had shown promising cytotoxic activity in various tumor models. The compound exhibited severe toxicity to hepatocytes and bone marrow cells. The present work was aimed to evaluate the molecular mechanism of the toxicity of indicine N-oxide. We found that indicine N-oxide inhibited the proliferation of various cancer cell lines in a concentration dependent manner with IC50 ranging from 46 to 100 μM. At the half maximal inhibitory concentration it blocked the cell cycle progression at mitosis without significantly altering the organization of the spindle and interphase microtubules. The toxicities of the compound at higher concentrations are attributed to its severe depolymerizing effect on both the interphase and spindle microtubules. Binding studies using purified goat brain tubulin indicated that indicine N-oxide binds to tubulin at a distinct site not shared by colchicine or taxol. It decreased the polymer mass of both purified tubulin and MAP-rich tubulin. It was found to induce cleavage of DNA using pUC18 plasmid. The interactions of indicine N-oxide on DNA were also confirmed by computational analysis; which predicted its binding site at the minor groove of DNA. These studies bring to light that the toxicities of indicine N-oxide were due to its DNA damaging effects and depolymerization of microtubules.