Human serum albumin–malathion complex study in the presence of silver nanoparticles at different sizes by multi spectroscopic techniques

<p>The binding of malathion to human serum albumin (HSA) in the presence of silver nanoparticles (AgNPs) was investigated for the first time by multiple spectroscopic methods such as fluorescence quenching, fluorescence resonance energy transfer (FRET), circular dichroism, red-edge excitation shift (REES), synchronous fluorescence and three dimensional fluorescence spectroscopy under physiological conditions .The results indicated that binding of malathion to HSA induced fluorescence quenching through static mechanism. The number of binding sites was calculated by double logarithmic equation. Changes in the micro-environment of the fluorophore residues were also probed by synchronous fluorescence spectroscopy and REES. Changes of secondary structure of HSA in HSA–malathion complex was verified by circular dichroism approach in the presence of AgNPs that showed the electrostatic interaction changes in the protein structure. The binding average distance (<i>r</i>) between the donor (HSA) and the acceptor (malathion) was measured and found to be 1.63 nm according to the Forster’s theory of non-radiation energy transfer which was <7 nm confirmed the existence of static quenching in the presence of AgNPs. The conformational changes of HSA by three-dimensional fluorescence spectroscopy were studied. By comparing the resonance light scattering in the binary and ternary systems, we could estimate the effect of AgNPs on the precipitation of the malathion on the HSA. Generally we have discussed the toxicity reduction effect of malathion in food industrial by the results of spectroscopy techniques.</p

Spectroscopic investigation of Bovine Liver Catalase interactions with a novel phen-imidazole derivative of platinum

<p>Successful clinical experience of using cisplatin and its derivatives in cancer therapy has encouraged scientists to synthesize new metal complexes with the aim of interacting with special targets such as proteins In this regard, biological effects of [Pt(FIP)(Phen)](NO₃)₂ compound which contains a novel phen-imidazole ligand, FIP, was investigated on bovine liver catalase (BLC) structure and function. Various spectroscopic methods such as UV–visible, fluorescence, and circular dichroism (CD) were applied at two temperatures 25 and 37°C for kinetics and structural studies. As a consequence, the enzymatic activity decreased slightly with increasing the platinum compound’s concentration up to 30 μM and then remained constant at near 80% after this concentration. On the other hand, the fluorescence quenching measurements revealed that despite slight changes in activity, catalase experiences notable alterations in three-dimensional environment around the chromophores of the enzyme structure with increasing platinum complex concentration. Moreover, quenching data showed that BLC has two binding sites for Pt complex and hydrogen bonding interactions play a major role in the binding process. Furthermore, CD spectroscopy data showed that Pt(II) complex induces significant decrease in α-helix content of the secondary structure of BLC, but notable increase in random coil proportion accompanying a slight decrease in β-sheet content. All in all, hydrogen bonding interactions which are mainly involved in the binding process of the novel phen-imidazole compound to BLC significantly alter the protein structure but slightly change its function. This might be a promising outcome for chemotherapists and medicinal chemists to investigate <i>in vivo</i> properties of this novel metal complex with significant binding tendency to a macromolecule in the low concentrations without decreasing its intrinsic function.</p

Effect of lipophilicity of amylamine and amylglycine ligands on biological activity of new anticancer cisplatin analog

<p>Investigation of side effects and solubility of anticancer drugs is a major challenge in chemotherapy science. Thus, design and synthesis of cisplatin analogs with higher lipophilicity as novel water-soluble anticancer drugs is valuable. In this work, two new Pt(II) complexes were synthesized with formula cis-[Pt(NH₃)₂(amylgly)]NO₃ and cis-[Pt(amylamine)₂(amylgly)]NO₃, where gly is penthyl glycine as an amino acid. The new compounds were synthesized and extensively characterized using analytical techniques; spectroscopic methods, and conductivity measurement. The anticancer activity of synthesized complexes was investigated against colon cancer cell line HCT116 using MTT assay and results showed excellent anticancer activity with <i>C</i>c₅₀ values of 36 and 270 M after 24-h incubation time for cis-[Pt(NH₃)₂(amylgly)]NO₃ and cis-[Pt(NH₂-amyl)₂(amylgly)]NO₃, respectively; which is lower than that for cisplatin. These complexes were also interacted with highly polymerized calf thymus DNA and the binding mode of the complexes to CT-DNA was evaluated by fluorescence, circular dichroism, and UV spectroscopy. The calculation of binding and thermodynamic of Pt(II) complexes with CT-DNA can provide deeper insight into mechanism of the action of these types of complexes with nucleic acids. So, thermodynamic parameters were also determined according to isothermal titration. In comparison with cis-[Pt(NH₃)₂(amylgly)]NO₃ in DNA interaction, the result show that cis-[Pt(NH₂-amyl)₂(amylgly)]NO₃ has higher affinity with binding constant K_f = 8.72 mM to CT-DNA. The results indicate that cis-[Pt(amylamine)₂(amylgly)]NO₃ with large and bulky aliphatic group bind to CT-DNA by different modes and covalent and groove bindings were preferred mode of interaction with DNA.</p

Improving activity of anticancer oxalipalladium analog by the modification of oxalate group with isopentylglycine

<p>In this article, we describe the influence of structure on biological behavior of amino acid-Pd complex and compare it with oxalipalladium. A new water-soluble oxalipalladium analog with formula of [Pd(DACH)(isopentylgly)](NO₃), where DACH is 1<i>R</i>,2<i>R</i>-diaminocyclohexane, has been synthesized and characterized by elemental analysis, conductivity measurements, IR, UV–Vis, and ¹H NMR spectroscopies. The interactions of oxalipalladium and its amino acid derivative with highly polymerized calf-thymus DNA have been extensively studied by spectroscopic methods. The high binding constants of oxalipalladium (0.38 × 10⁴ M⁻¹) and new amino acid-Pd complex (0.65 × 10⁴ M⁻¹) were determined using absorption measurements. Also circular dichroism (CD) studies show that Pd complex causes more disturbances on DNA structure rather than oxalipalladium. The experimental results proposed that [Pd(DACH)(isopentylgly)](NO₃) is bound to DNA by groove-binding mode as well as partially covalent interaction, while oxalate analog binds covalently to DNA after hydrolysis. Interaction of the two metal derivative complexes was studied by molecular docking simulation. The results showed that amino acid-Pd complex has higher negative docking energy and higher tendency for interaction with DNA, and exert more structural change on DNA. Finally, the anticancer and growth inhibitory activities of synthesized complexes were investigated against human colon cancer cell line of HCT116 after 24  h incubation time using MTT assay. Results show that the complex [Pd(DACH)(isopentylgly)](NO₃) showed enhanced anticancer and growth inhibitory activities against human colon can cell line HCT116.</p

Multi-spectroscopic and electrochemical approaches of the interaction between a new binuclear agent and DNA

Multi-spectroscopic and electrochemical approaches of the interaction between a new binuclear agent and DN