piperidines and azobenzene

We previously developed, synthesized and tested light-activated sulfonylureas for optical control of K

Topics: Adenosine Triphosphate; Azetidines; Humans; Insulin-Secreting Cells; Piperidines; Pyrrolidines; Sulfonylurea Compounds

Supramolecular chemistry addresses intermolecular forces and consequently promises great flexibility and precision. Biological systems are often the inspirations for supramolecular research. The G-quadruplex (G4) belongs to one of the most important secondary structures in nucleic acids. Until recently, the supramolecular manipulation of the G4 has not been reported. The present study is the first to disclose a supramolecular switch for the reversible control of human telomere G4s. Moreover, this supramolecular switch has been successfully used to manipulate an enzymatic reaction. Using various methods, we show that cucurbit[7]uril preferably locks and encapsulates the positively charged piperidines of Razo through supramolecular interactions. They can switch the conformations of the DNA inhibitor between a flexible state and the rigid G4 and are therefore responsible for the reversible control of the thrombin activity. Thus, our findings open a promising route and exhibit potential applications in future studies of chemical biology.

Topics: Azo Compounds; Base Sequence; Bridged-Ring Compounds; DNA; G-Quadruplexes; Humans; Imidazoles; Molecular Docking Simulation; Piperidines; Telomere; Thrombin

Hydrazobenzene is carcinogenic to rats and mice and azobenzene is carcinogenic to rats. Hydrazobenzene is a metabolic intermediate of azobenzene. To clarify the mechanism of carcinogenesis by azobenzene and hydrazobenzene, we investigated DNA damage induced by hydrazobenzene, using 32P-5'-end-labeled DNA fragments obtained from the c-Ha-ras-1 protooncogene and the p53 tumor suppressor gene. Hydrazobenzene caused DNA damage in the presence of Cu(II). Piperidine treatment enhanced the DNA damage greatly, suggesting that hydrazobenzene caused base modification and liberation. However, azobenzene did not cause DNA damage even in the presence of Cu(II). Hydrazobenzene plus Cu(II) caused DNA damage frequently at thymine residues. Catalase and a Cu(I)-specific chelator inhibited Cu(II)-mediated DNA damage by hydrazobenzene. Typical *OH scavengers did not inhibit the DNA damage. The main active species is probably a metal oxygen complex, such as Cu(I)-OOH. Formation of 8-oxo-7, 8-dihydro-2'-deoxyguanosine was increased by hydrazobenzene in the presence of Cu(II). Oxygen consumption and UV-Visible spectroscopic measurements have shown that hydrazobenzene is autoxidized to azobenzene with H2O2 formation. It is considered that the metal-mediated DNA damage by hydrazobenzene through H2O2 generation may be relevant for the expression of carcinogenicity of azobenzene and hydrazobenzene.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Azo Compounds; Catalase; Cattle; Chelating Agents; Copper; Deoxyguanosine; DNA; DNA Damage; Free Radical Scavengers; Humans; Hydrogen Peroxide; Hydroxyl Radical; Oxidation-Reduction; Phenanthrolines; Phenylhydrazines; Piperidines

Synthesis, analytical performances, thermodynamic and surface properties of two new liquid crystals substituted with poly(ethylene oxide) chains are described. The first of them is N,N'-diphenyl-[4-[2,3,4-tri[2-(2-metoxyethoxy)ethoxy]benzylidene]i mine]piperidine (LC1) and the second is 2-hydroxy-3-methyl-4-[4-[2-(2-butoxyethoxy)ethoxy]] 4'-[4-[2-(2-butoxyethoxy)ethoxy]styryl]azobenzene (LC2). The nematic ranges of the two liquid crystals, determined by differential scanning calorimetry do not interfere. The analytical and thermodynamic studies of LC1 and LC2 in the solid, nematic and liquid state were done using a series of appropriate solutes. Comparison of the analytical performances shows a better efficiency in the nematic state.

Topics: Azo Compounds; Calorimetry, Differential Scanning; Chromatography, Gas; Crystallization; Piperidines; Thermodynamics