3-Aminoxypropionate-based linker system for cyclization activation in prodrug design

Discovery of a Tricyclic β-Lactam as a Potent Antimicrobial Agent against Carbapenem-Resistant Enterobacterales, Including Strains with Reduced Membrane Permeability and Four-Amino Acid Insertion into Penicillin-Binding Protein 3: Structure-Activity-Relationships and In Vitro and In Vivo Activities

The current worldwide emergence of carbapenem-resistant enterobacterales (CREs) constitutes an important growing clinical and public health threat. Acquired carbapenemases are the most important determinants of resistance to carbapenems. In the development of the previously reported tricyclic β-lactam skeleton which exhibits potent antibacterial activities against several problematic β-lactamase-producing CREs without a β-lactamase inhibitor, we found that these activities were reduced against clinical isolates with resistance mechanisms other than β-lactamase production. These mechanisms were the reduction of outer membrane permeability with the production of β-lactamases and the insertion of four amino acids into penicillin-binding protein 3. Here, we report the discovery of a potent compound that overcomes these resistance mechanisms by the conversion of the alkoxyimino moiety of the aminothiazole side chain in which a hydrophilic functional group is introduced and the carboxylic acid of the alkoxyimino moiety is converted to reduce the negative charge of the whole molecule from 2 to 1. This potent tricyclic β-lactam is a promising drug candidate for infectious diseases caused by CREs due to its potent therapeutic efficacy in the neutropenic mouse lung infection model and low frequency of producing spontaneously resistant mutants.

Aminooxylated Carbohydrates: Synthesis and Applications

Among other classes of biomolecules, carbohydrates and glycoconjugates are widely involved in numerous biological functions. In addition to addressing the related synthetic challenges, glycochemists have invested intense efforts in providing access to structures that can be used to study, activate, or inhibit these biological processes. Over the past few decades, aminooxylated carbohydrates have been found to be key building blocks for achieving these goals. This review provides the first in-depth overview covering several aspects related to the syntheses and applications of aminooxylated carbohydrates. After a brief introduction to oxime bonds and their relative stabilities compared to related C═N functions, synthetic aspects of oxime ligation and methodologies for introducing the aminooxy functionality onto both glycofuranosyls and glycopyranosyls are described. The subsequent section focuses on biological applications involving aminooxylated carbohydrates as components for the construcion of diverse architectures. Mimetics of natural structures represent useful tools for better understanding the features that drive carbohydrate-receptor interaction, their biological output and they also represent interesting structures with improved stability and tunable properties. In the next section, multivalent structures such as glycoclusters and glycodendrimers obtained through oxime ligation are described in terms of synthetic design and their biological applications such as immunomodulators. The second-to-last section discusses miscellaneous applications of oxime-based glycoconjugates, such as enantioselective catalysis and glycosylated oligonucleotides, and conclusions and perspectives are provided in the last section.

Changes in dynamics of α-chymotrypsin due to covalent inhibitors investigated by elastic incoherent neutron scattering

The dynamics of chymotrypsin increases when bound to two different covalent inhibitors. These effects were analyzed by univariate and multivariate methods.

Design, synthesis, and evaluation of potential prodrugs of DFMO for reductive activation

A series of potential DFMO prodrugs was designed through the incorporation of 4-nitrobenzyl ester or carbamate groups for potential activation by trypanosomal nitroreductase. It was found that only modification of N(ε)-amino group of DFMO by 4-nitro-2-fluorobenzyloxycarbonyl resulted in significant trypanocidal activity and could serve as a lead for further investigation.