Urease inhibitors are considered promising compounds for the treatment of ureolytic bacterial infections, particularly infections resulting from Helicobacter pylori in the gastric tract. Herein, we present the synthesis and the inhibitory activity of novel and highly effective organoselenium compounds as inhibitors of Sporosarcina pasteurii and Helicobacter pylori ureases. These studied compounds represent a class of competitive reversible urease inhibitors. The most active compound, 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen), displayed Ki values equal to 2.11 and 226 nM against S. pasteurii and H. pylori enzymes, respectively, indicating ebselen as one of the most potent low-molecular-weight inhibitors of bacterial ureases reported to date. Most of these molecules penetrated through the cell membrane of the Gram-negative bacteria Escherichia coli (pGEM::ureOP) in vitro. Furthermore, whole-cell studies on the H. pylori J99 reference strain confirmed the high efficiency of the examined organoselenium compounds as urease inhibitors against pathogenic bacteria.

The incorporation of cyclopentane-based beta-amino acid in the sequence of peptide forming coiled-coil induced formation of nanofibrils.

Quinines phosphorylated at the C-9 hydroxyl group (diphenyl and diethyl phosphates) were synthesized and validated as novel effective chiral solvating agents in two alternative methods based on (1)H and (31)P NMR spectroscopy. Tested with a representative set of racemic analytes, the title compounds induced shift nonequivalence effects in (1)H NMR signals with values up to 0.1-0.2 ppm for 3,5-dinitrobenzoyl-substituted amino acids. In terms of enantiodifferentiation extent and application range, introduction of a phosphate group was proven to be superior compared to the action of nonmodified quinine. Interestingly, a temperature decrease to reach the slow exchange conditions also produced nonequivalences in the (31)P NMR spectra of the selectors. Comprehensive NMR analysis showed the existence of two conformations (closed 1 and 2) for both quinines in their free forms and the open 3 arrangement for the protonated ones. The crystal structure of diethylphosphorylquinine hydrochloride dichloromethane hemisolvate revealed a similar conformation to that observed in solution. Structures of complexes of phosphorylated quinines with selected ligands were determined with the use of NMR-based molecular modeling studies.

Peptide foldamers have been studied for over two decades and numerous sequence patterns have been shown to form well-defined three-dimensional arrangements in solution. In particular, helices of various geometries have been described. In this article, different concepts concerning the construction of helical foldameric peptides, for which the possibility of governing the sense of the formed helix was evidenced, are presented and discussed.