Density functional theory molecular modelling, DNA interactions, antioxidant, antimicrobial, anticancer and biothermodynamic studies of bioactive water soluble mixed ligand complexes

<p>A novel series of bioactive water soluble mixed ligand complexes (<b>1–5</b>) [M^II(L)(phen)AcO]. <i>n</i>H₂O {where M = Cu (<b>1</b>) <i>n</i> = 2; Co (<b>2</b>), Mn (<b>3</b>), Ni (<b>4</b>), <i>n</i> = 4 and Zn (<b>5</b>) <i>n</i> = 2} were synthesized from 2-(2-Morpholinoethylimino) methyl)phenol Schiff base ligand (<b>LH</b>), 1, 10-phenanthroline and metal(II) acetate salt in a 1:1:1 stoichiometric ratio and characterized by several spectral techniques. The obtained analytical and spectral data suggest the octahedral geometry around the central metal ion. Density functional theory calculations have been further supportive to explore the optimized structure and chemical reactivity of these complexes from their frontier molecular orbitals. Gel electrophoresis result indicates that complex (<b>1</b>) manifested an excellent DNA cleavage property than others. The observed binding constants with free energy changes by electronic absorption technique and DNA binding affinity values by viscosity measurements for all compounds were found in the following order (<b>1</b>) > (<b>2</b>) > (<b>4</b>) > (<b>5</b>) > (<b>3</b>) <b>></b> (<b>LH</b>). The binding results and thermodynamic parameters are described the intercalation mode. <i>In vitro</i> antioxidant properties disclose that complex (<b>1</b>) divulges high scavenging activity against DPPH^•, ^•OH, O₂^−• NO^•, and Fe³⁺. The antimicrobial reports illustrate that the complexes (<b>1–5</b>) were exhibited well defined inhibitory effect than ligand (<b>LH</b>) against the selected different pathogenic species. The observed percentage growth inhibition against A549, HepG2, MCF-7, and NHDF cell lines suggest that complex (<b>1</b>) has exhibited superior anticancer potency than others. Thus, the complex (<b>1</b>) may contribute as potential anticancer agent due to its unique interaction mode with DNA.GRAPHICAL ABSTRACT</p> <p>Communicated by Ramaswamy H. Sarma</p

Quantum mechanical study on complexation phenomenon of pillar[5]arene towards neutral dicyanobutane

Based on density functional theory calculations, we have addressed the electronic structure, binding and nature of non-covalent interactions between alkylated pillar[5]arene (P[5]A) and 1,4-dicyanobutane (DCB)-based host-guest macrocycles. Neutral 1,4-dicyanobutane-based alkylated DCB_ProP[5]A is found to show higher binding energy when compared to the other three host-guest macrocycles. These complexes are largely stabilised by non-covalent interactions, which are ascertained through NCI and QTAIM analyses. Furthermore, the second-order perturbation energy of NBO analysis show that LP (N) – σ*(C-H) interactions predominate in DCB_ProP[5]A complex. Particularly, alkyl substituents (-methyl, -ethyl and -propyl) are playing a vital role in stabilising the host-guest complexes. In summary, the present work not only exhibits an efficient strategy to build a new family of alkylated P[5]A inclusion complexes but also providing deeper understanding on various non-covalent interactions towards 1,4-dicyanobutane (DCB) guest molecules inside the host environment.</p

Surfactant–copper(II) Schiff base complexes: synthesis, structural investigation, DNA interaction, docking studies, and cytotoxic activity

<div><p>A series of surfactant–copper(II) Schiff base complexes (<b>1–6</b>) of the general formula, [Cu(sal-R₂)₂] and [Cu(5-OMe-sal-R₂)₂], {where, sal = salicylaldehyde, 5-OMe-sal = 5-methoxy- salicylaldehyde, and R₂ = dodecylamine (DA), tetradecylamine (TA), or cetylamine (CA)} have been synthesized and characterized by spectroscopic, ESI-MS, and elemental analysis methods. For a special reason, the structure of one of the complexes (<b>2</b>) was resolved by single crystal X-ray diffraction analysis and it indicates the presence of a distorted square-planar geometry in the complex. Analysis of the binding of these complexes with DNA has been carried out adapting UV-visible-, fluorescence-, as well as circular dichroism spectroscopic methods and viscosity experiments. The results indicate that the complexes bind via minor groove mode involving the hydrophobic surfactant chain. Increase in the length of the aliphatic chain of the ligands facilitates the binding. Further, molecular docking calculations have been performed to understand the nature as well as order of binding of these complexes with DNA. This docking analysis also suggested that the complexes interact with DNA through the alkyl chain present in the Schiff base ligands via the minor groove. In addition, the cytotoxic property of the surfactant–copper(II) Schiff base complexes have been studied against a breast cancer cell line. All six complexes reduced the visibility of the cells but complexes 2, 3, 5, and 6 brought about this effect at fairly low concentrations. Analyzed further, but a small percentage of cells succumbed to necrosis. Of these complexes (<b>6</b>) proved to be the most efficient aptotoxic agent.</p></div