A domino process is described combining an ene reaction between two alkynes and a Diels-Alder cycloaddition of the vinylallene formed. The process accounts for the thermally induced cycloisomerization of macrocyclic triynes and enediynes to give fused tetracycles in a stereoselective manner.

vilsmeier several diamide derivatives containing 2-chloroquinoline scaffolds were synthesized via ugi reaction of 2-chloroquinoline-3-carboxaldehydes, amines, carboxylic acids and isocyanides. the diversity of these quinolinyl ugi-adducts was increased by using 2-chloroquinoline-3-carboxylic acids as a source of acid. among them, compounds 2d, 2n, 2p, 4a, 4c and 4e displayed moderate to good an...

A new method for the covalent modification of poly­ mers in a two-step process is described. Squaric acid di­ ethylester reacts with primary or secondary aliphatic amines selectively to ester amides. It is shown for the first time that this class of compounds react with poly­ meric systems containing amine functionalities (e.g. g-amino groups of proteins) in aqueous solution, form­ ing stable s...

Genetically engineered production of 1-desmethylcobyrinic acid, 1desmethylcobyrinic acid a,c-diamide, and cobyrinic acid a,c-diamide in E. coli implies a role for CbiD in C-1 methylation in the anaerobic pathway to cobalamin* Charles A. Roessner, Howard J. Williams, and A. Ian Scott Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255 Running ...

AIMS Trypanosomatids have a unique trypanothione-based thiol redox metabolism. The parasite-specific dithiol is synthesized from glutathione and spermidine, with glutathionylspermidine as intermediate catalyzed by trypanothione synthetase. In this study, we address the oxidative stress response of African trypanosomes with special focus on putative protein S-thiolation. RESULTS Challenging bl...

Xie C, Biary N, Tocchetti CG, Aon MA, Paolocci N, Kauffman J, Akar FG. Glutathione oxidation unmasks proarrhythmic vulnerability of chronically hyperglycemic guinea pigs. Am J Physiol Heart Circ Physiol 304: H916 –H926, 2013. First published February 1, 2013; doi:10.1152/ajpheart.00026.2012.—Chronic hyperglycemia in type-1 diabetes mellitus is associated with oxidative stress (OS) and sudden de...

P-glycoprotein, encoded by the multidrug resistance gene MDR1, is an ATP-driven drug efflux pump which is highly expressed at the blood-brain barrier of vertebrates. Drug efflux of macrocyclic lactones by P-glycoprotein is highly relevant for the therapeutic safety of macrocyclic lactones, as thereby GABA-gated chloride channels, which are confined to the central nervous system in vertebrates, ...

Red blood cells (RBCs) deformability can be defined as the ability of the cells to deform when subjected to certain flow conditions. In this work, a microfluidic system composed of a microchannel with a hyperbolic-shaped contraction was used to investigate the effect of both diamide and glutaraldehyde on the cell deformation index (DI) of human and ovine RBCs. An adequate image analysis techniq...

Reaction between 4-aminopyridine and a dinuclear zinc(II) component of a Robson macrocyclic ligand has resulted in the formation of a molecular ladder element motif. X-ray single crystal structural analysis indicates that two pyridine rings are assembled at the same direction of the macrocycle, which are placed in a nearly parallel way via pi-pi interactions, forming a concavity structure with ...