Binding and photocleavage of a neutral nickel(II) bis(hydrogen pyridine-2,6-dicarboxylato) complex to DNA

Spectroscopic and molecular modeling methods to investigate the interaction between psycho-stimulant modafinil and calf thymus DNA using ethidium bromide as a fluorescence probe

Interaction type of modafinil with calf thymus DNA (ct-DNA) was examined systematically using ethidium bromide (EB) as a fluorescence probe by fluorescence spectroscopy, UV-Vis spectroscopy, viscosity and molecular docking method. The fluorescence quenching mechanism of ct-DNA-EB by modafinil can be combination of static and dynamic quenching. Results of UV-Vis absorption, competitive binding with Hoechst 33258, ionic strength effect studies, viscosity measurements were confirmed that the interaction type of modafinil with ct-DNA was intercalation. According to docking studies R-modafinil showed better interaction with ct-DNA which is consistent with known pharmacological properties of modafinil. The calculated thermodynamic parameters, enthalpy and entropy change, suggested that the driven forces are hydrogen bonding or van der Walls forces. Results of the docking studies were compatible with the experimental results and confirmed the hydrogen bond formation between modafinil and ct-DNA.

Design, synthesis, and DNA interaction studies of furo-imidazo[3.3.3]propellane derivatives: Potential anticancer agents

A large number of natural products containing the propellane scaffold have been reported to exhibit cytotoxicity against several cancers; however, their mechanism of action is still unknown. Anticancer drugs targeting DNA are mainly composed of small planar molecule/s that can interact with the DNA helix, causing DNA malfunction and cell death. The aim of this study was to design and synthesize propellane derivatives that can act as DNA intercalators and/or groove binders. The unique structure of the propellane derivatives and their ability to display planar ligands with numerous possible geometries, renders them potential starting points to design new drugs targeting DNA in cancer cells. New substituted furo-imidazo[3.3.3]propellanes were synthesized via the reaction of substituted alkenylidene-hydrazinecarbothioamides with 2-(1,3-dioxo-2,3-dihydro-1H-2-ylidene)propanedinitrile in tetrahydrofuran at room temperature. The structures of the products were confirmed by a combination of elemental analysis, NMR, ESI-MS, IR and single crystal X-ray analysis. Interestingly, 5c, 5d and 5f showed an ability to interact with Calf Thymus DNA (CT-DNA). Their DNA-binding mode was investigated using a combination of absorption spectroscopy, DNA melting, viscosity, CD spectroscopy measurements, as well as competitive binding studies with several dyes. Their cytotoxicity was evaluated against the NCI-60 panel of cancer cell lines. 5c, 5d and 5f exhibited similar anti-proliferative activity against the A549 non-small cell lung cancer (NSCLC) cell line. Further mechanistic studies revealed their ability to induce DNA damage in the A549 cell line, as well as apoptosis, evidenced by elevated Annexin V expression, enhanced caspase 3/7 activation and PARP cleavage. In this study, we present the potential for designing novel propellanes to provoke cytotoxic activity, likely through DNA binding-induced DNA damage and apoptosis.

Spectroscopic and molecular modeling based approaches to study on the binding behavior of DNA with a copper (II) complex

Blocking the division of tumor cells by small-molecules is currently of great interest for the design of new antitumor drugs. The interaction of a new metal complex with DNA was investigated through several techniques. Absorption spectroscopy and gel electrophoresis studies on the interaction of the Cu-complex of (2a-4mpyH)2 [Cu(pyzdc)2 (H2O)2].6 H2O with DNA have shown that this complex can bind to CT-DNA with binding constant 3.99 × 10(5) M(-1). The cyclic voltammetry (CV) responses of the metal complex in the presence of CT-DNA have shown that the metal complex can bind to CT-DNA through partial intercalation mode and this is consistent with molecular docking analysis, quenching process and thermal denaturation experiments. The cytotoxicity of this complex has been evaluated by MTT assay. The results of cell viability assay on DU145 cell line revealed that the metal complex had cytotoxic effects.