Synthesis, characterization and DNA interaction studies of a new platinum(II) complex containing caffeine and histidine ligands using instrumental and computational methods

<div><p>A new Pt(II) complex, [Pt(Caff)(His)(Cl)] (Caff is Caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) and His is l-Histidine), was synthesized and characterized using different physicochemical methods. The interaction of this complex with calf thymus DNA (ct-DNA) was investigated by absorption, emission, circular dichroism (CD), and viscosity measurements and molecular docking techniques. The calculated binding constant, <i>K</i>_b, was 5.3 × 10³ M⁻¹. In fluorimetric studies, the enthalpy and entropy of the reaction between the complex and ct-DNA showed that the reaction is exothermic (∆<i>H</i> = −184.07 kJ mol⁻¹, ∆<i>S</i> = −551.97 J mol⁻¹ K⁻¹). CD spectra of DNA in the presence of different amounts of the complex showed little changes in both the negative and positive band intensities, which imply a non-intercalative mode between the DNA and the platinum complex. Furthermore, the study of molecular docking also indicated that the complex binds to DNA via a groove binding mode.</p></div

Synthesis of a new Pt(II) complex containing valganciclovir drug and calf-thymus DNA interaction study using multispectroscopic methods

<p>A new complex, [Pt(valcyte)(DMSO)Cl]Cl, in which valcyte (trade name) served as valganciclovir hydrochloride drug ([2-[(2-amino-6-oxo-3H-purin-9-yl)methoxy]-3-hydroxypropyl](2S)-2-amino-3-methylbutanoate), was synthesized and characterized by different physicochemical methods. Binding interaction of this complex with calf<b>-</b>thymus DNA (ct-DNA) has been investigated by multispectroscopic techniques. The complex displays significant binding properties with ct-DNA. The results of fluorescence and UV–vis absorption spectroscopy indicated that this complex interacted with ct-DNA in a groove-binding mode, and the binding constant was 3.8 × 10⁴ M⁻¹. Furthermore, the complex induced detectable changes in the CD spectrum of ct-DNA and slightly changed its viscosity which verified the groove-binding mode. Finally, all results indicated that Pt(II) complex interact with DNA via groove-binding mode.</p

Synthesis, characterization and comparative DNA interaction studies of new copper(II) and nickel(II) complexes containing mesalamine drug using molecular modeling and multispectroscopic methods

<div><p>Complexes of copper(II) and nickel(II) containing the drug mesalamine (5-ASA) have been synthesized and characterized by FT-IR, mass and UV–vis spectra, elemental analysis, and theoretical methods. The binding interactions between mesalamine and its Cu(II) and Ni(II) complexes with calf thymus DNA (ct-DNA) were investigated using absorption, fluorescence emission and circular dichroism (CD) spectroscopies, and viscosity measurements. Absorption spectra of 5-ASA, Cu(II) and Ni(II) complexes showed hypochromism. The calculated binding constants (<i>K</i>_b) obtained from UV–vis absorption studies were 1.27 × 10³, 1.6 × 10³, and 1.2 × 10⁴ M⁻¹ for 5-ASA, Cu(II) and Ni(II) complexes, respectively. The compounds induced detectable changes in the CD spectra of ct-DNA (B → A structural transition, B → C structural transition and stabilization of the right-handed B form, for mesalamine, Cu(II) and Ni(II) complexes, respectively). The competitive binding experiments with Hoechst 33258 indicated that 5-ASA and copper complex could interact as groove binders. Furthermore, Ni complex had no effect on the fluorescence intensity and peak position of MB-DNA system. Finally, the results obtained from experimental and molecular modeling showed that complexes bind to DNA via minor-groove binding.</p></div

Synthesis, characterization, molecular modeling, and DNA interaction studies of a Cu(II) complex containing drug of chronic hepatitis B: adefovir dipivoxil

<div><p>A new copper(II) complex [Cu(adefovir)₂Cl₂], where adefovir = adefovir dipivoxil drug, was synthesized and characterized by using different physicochemical methods. Binding interaction of this complex with calf thymus DNA (ct-DNA) has been investigated by multi-spectroscopic techniques and molecular modeling study. The complex displays significant binding properties of ct-DNA. The results of fluorescence and UV–vis absorption spectroscopy indicated that, this complex interacted with ct-DNA in a groove-binding mode, and the binding constant was 4.3(±0.2)  ×  10⁴ M⁻¹. The fluorimeteric studies showed that the reaction between the complex and ct-DNA is exothermic (Δ<i>H</i> = 73.91 kJ M⁻¹; Δ<i>S</i> = 357.83 J M⁻¹ K⁻¹). Furthermore, the complex induces detectable changes in the CD spectrum of ct-DNA and slightly increases its viscosity which verified the groove-binding mode. The molecular modeling results illustrated that the complex strongly binds to the groove of DNA by relative binding energy of the docked structure −5.74 kcal M⁻¹. All experimental and molecular modeling results showed that the Cu(II) complex binds to DNA by a groove-binding mode.</p></div

Human serum albumin interaction studies of a new copper(II) complex containing ceftobiprole drug using molecular modeling and multispectroscopic methods

<p>A copper(II) complex containing the ceftobiprole drug and 1,10-phenanthroline (phen) has been synthesized and characterized by UV–vis, FT-IR and mass spectra, and elemental analysis. The binding interaction between [Cu(cef)(phen)Cl₂] complex and human serum albumin (HSA) was investigated using absorption, fluorescence emission and circular dichroism spectroscopies, and molecular docking. Thermodynamic parameters (Δ<i>H</i> < 0 and Δ<i>S</i> < 0) indicated that the hydrogen bond and van der Waals interactions played main roles in the binding of complex [Cu(cef)(phen)Cl₂] to HSA. The results of CD and UV–vis spectroscopy showed that the binding of [Cu(cef)(phen)Cl₂] to HSA induces some conformational changes in HSA. Displacement experiments predicted that the binding of [Cu(cef)(phen)Cl₂] complex to HSA is located within domain III, Sudlow’s site 2, and these observations were substantiated by molecular docking studies.</p

Synthesis, structural determination and HSA interaction studies of a new water-soluble Cu(II) complex derived from 1,10-phenanthroline and ranitidine drug

<p>A new water-soluble Cu(II) complex containing ranitidine drug and 1,10-phenanthroline was synthesized and characterized by elemental analysis, molar conductivity, spectroscopic and computational methods. <i>In vitro</i> human serum albumin (HSA)-interaction studies of Cu(II) complex were performed by employing fluorescence spectroscopy in combination with UV–vis absorption and circular dichroism (CD) spectroscopies. The results of fluorescence titration showed that Cu(II) complex strongly quenched the intrinsic fluorescence of HSA through a static quenching mechanism with an intrinsic binding constant (6.05 × 10⁴ M⁻¹) at 286 K. The thermodynamic parameters Δ<i>G</i>, Δ<i>H</i>, and Δ<i>S</i> at different temperatures were calculated and suggested that the hydrophobic and hydrogen bonding interactions play major roles in Cu(II) complex-HSA association. The displacement experiments using warfarin and ibuprofen as site I and II probes proved that the Cu(II) complex could bind to site I (subdomain IIA) of HSA. Finally, CD spectra indicated that the interaction of the Cu(II) complex with HSA leads to an increase in the α-helical content. The main result of this study was the finding that the binding affinity of the Cu(II) complex to HSA is three orders of magnitude stronger than that of ranitidine drug.</p

Synthesis, characterization and <i>in vitro</i> DNA binding studies of a new copper(II) complex containing antioxidant ferulic acid

<p>A mononuclear Cu(II) complex, [Cu(FA)₂(NO₃)₂], in which FA is ferulic acid ((E)-3-(4-hydroxy-3-methoxy-phenyl)prop-2-enoic acid), was synthesized and characterized by spectroscopic methods. The main structures of the ligand and its complexes with Cu²⁺ were optimized by QM calculations. The calculations on the structures of the [Cu(FA)₂(NO₃)₂] complexes forms and the intercalating with DNA profile were undertaken by UHF/PM6 and MMFF94 methods, respectively. <i>In vitro</i> studies (UV-vis spectroscopy, emission titration, circular dichroism techniques, and viscometry) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) showed that the complex interacts with calf-thymus DNA (ct-DNA) via an intercalative binding mode. The thermodynamic parameters, enthalpy change (ΔH), and entropy change (ΔS) showed that the acting forces between Cu(II) complex and ct-DNA mainly included van der Waals interactions and hydrogen bonds. Methylene blue (MB) displacement studies revealed that Cu(II) complex can substitute MB probe in the MB-DNA complex which was indicative of intercalative binding. The theoretical data confirm the experimental results with respect to the mechanism of binding.</p