RESUMEN

Therapeutic oligonucleotides are chemically modified to enhance their drug-like properties - including binding affinity for target RNA. Many nucleic acid analogs that enhance RNA binding affinity constrain the furanose sugar in an RNA-like sugar pucker. The improvements in binding affinity result primarily from increased off-rates with minimal effects on on-rates for hybridization. To identify alternate chemical modification strategies that can modulate on- and off-rates for oligonucleotide hybridization, we hypothesized that extending conformational restraint across multiple nucleotides could modulate hybridization kinetics by restricting rotational freedom of the sugar-phosphate backbone. As part of that effort, we recently reported that using hydrocarbon tethers to bridge adjacent phosphodiester linkages as phosphonate tethered bridges can pre-organize nucleic acids in conformations conducive for Watson-Crick base-pairing and modulate hybridization kinetics. In this report, we describe the synthesis of locked nucleic acid (LNA) trimers linked through alkylphosphonate tethers which restrict conformation of the furanose sugar in addition to restricting conformational mobility of the sugar-phosphate backbone across three nucleotide units.

RESUMEN

Tissue transglutaminase (TG2) is a multifunctional protein that catalyses protein crosslinking in the extracellular matrix, and functions as an intracellular G-protein. While both activities have been associated with human diseases, its role as a G-protein has been linked to cancer stem cell survival and maintenance of a metastatic phenotype. Recently we have shown that targeted covalent inhibitors (TCIs) can react selectively with the enzyme active site of TG2, to allosterically abolish its ability to bind GTP. In the present work, we focused on the variation of the N-terminal group of these peptidomimetic inhibitors, in order to enhance efficiency, while reducing log P and the number of rotatable bonds. This approach led to the synthesis and evaluation of 41 novel inhibitors, some of which had greatly improved efficiency and affinity for TG2 (e.g. TCI 72: KI = 1.0 µM, kinact/KI = 4.4 × 105 M-1 min-1). Molecular modelling provided a hypothetical binding mode for these TCIs. The most efficient inhibitors were evaluated further and shown to have excellent isozyme selectivity, to block GTP binding, and to have improved pharmacokinetic properties, as expected. Their biological activity was also confirmed, in a cellular invasion assay, although with less potency than expected.

Asunto(s)

RESUMEN

BACKGROUND: Multicomponent processes have played powerful roles in achieving complex structures, which are also aligned with green chemistry. Thus, MCRs have attracted considerable interest due to their atom economy, simple experimental procedures, automated synthesis, convenience and synthetic efficiency. Isocyanides are one of the crucial starting material in designing MCRs methods. They are unique building blocks in many cycloaddition reactions since they are able to react with both nucleophiles and electrophiles at the same carbon. Furthermore, ammonium chloride is an inorganic compound that is highly soluble in water, inexpensive and commercially available. Solutions of ammonium chloride are mildly acidic and have been used in various reactions. OBJECTIVE: This article focuses on design a convenient and straightforward method for assembling important scaffolds such imidazolidinones through one-pot three-component strategy. CONCLUSION: The straightforward and efficient one-pot three component method for the synthesis of 4-(cyclohexylmethylene)-5-phenylimidazolidin-2-one derivatives is described. This reaction exploits the formation of imine, which undergoes spontaneous intermolecular cycloaddition with isocyanide, and generates the desired products in a good yield.

Asunto(s)

RESUMEN

A palladium-catalyzed multicomponent route to polycyclic pyrroles is described. Pd(PtBu3)2 was found to catalyze the coupling of (hetero)aryl iodides, two equivalents of carbon monoxide and alkyne-tethered imines into 1,3-dipoles (Münchnones), which undergo spontaneous, intramolecular 1,3-dipolar cycloaddition to form polycyclic pyrroles. The systematic variation of the alkyne, tethered-imine, or aryl iodide can allow the buildup of a range of pyrrole derivatives, where any of the substituents can be independently varied. In addition, the same palladium catalyst can be employed in an initial Sonogashira-type coupling with aryl iodides, which upon the addition of CO can allow the novel tandem catalytic, five component synthesis of diversely substituted products.