A versatile synthetic approach toward diversity libraries using monosaccharide scaffolds.

The pyranose scaffold is unique in its ability to position pharmacophore substituents in various ways in 3D space, and unique pharmacophore scanning libraries could be envisaged that focus on scanning topography rather than diversity in the type of substituents. Approaches have been described that make use of amine and acid functionalities on the pyranose scaffolds to append substituents, and this has enabled the generation of libraries of significant structural diversity. Our general aim was to generate libraries of pyranose-based drug-like mimetics, where the substituents are held close to the scaffold, in order to obtain molecules with better defined positions for the pharmacophore substituents. Here we describe the development of a versatile synthetic route toward peptide mimetics build on 2-amino pyranose scaffolds. The method allows introduction of a wide range of substituent types, it is regio- and stereospecific, and the later diversity steps are performed on solid phase. Further, the same process was applied on glucose and allose scaffolds, in the exemplified cases, and is likely adaptable to other pyranose building blocks. The methods developed in this work give access to molecules that position the three selected binding elements in various 3D orientations on a pyranose scaffold and have been applied for the production of a systematically diverse library of several hundred monosaccharide-based mimetics.

Carbohydrate-based scaffolds in drug discovery.

Carbohydrates have been proven as valuable scaffolds to display pharmocophores and the resulting molecules have demonstrated useful biological activity towards various targets including the somatostatin receptors (SSTR), integrins, HIV-1 protease, matrix metalloproteinases (MMP), multidrug resistance-associated protein (MRP), and as RNA binders. Carbohydrate-based compounds have also shown antibacterial and herbicidal activity.

Zinc is not required for activity of TPO agonists acting at the c-Mpl receptor transmembrane domain.

Molecules that mimic the cytokine thrombopoietin that act by an atypical mechanism of binding to a receptor transmembrane (TM) domain are widely understood to require zinc for their biological activity. We investigated potent thrombopoietin mimetics from three chemical classes including the recently registered drug Eltrombopag, which operate via this novel mechanism, to determine whether zinc is essential for inducing cell proliferation. Using addition of zinc and a potent metal chelator, we show that the existing paradigm is incorrect and the compounds exhibit excellent thrombopoietin-mimetic activity even in the presence of high concentrations of EDTA. The implications of these findings for the mechanism of action are discussed.

Biological diversity from a structurally diverse library: systematically scanning conformational space using a pyranose scaffold.

Success in discovering bioactive peptide mimetics is often limited by the difficulties in correctly transposing known binding elements of the active peptide onto a small and metabolically more stable scaffold while maintaining bioactivity. Here we describe a scanning approach using a library of pyranose-based peptidomimetics that is structurally diverse in a systematic manner, designed to cover all possible conformations of tripeptide motifs containing two aromatic groups and one positive charge. Structural diversity was achieved by efficient selection of various chemoforms, characterized by a choice of pyranose scaffold of defined chirality and substitution pattern. A systematic scanning library of 490 compounds was thus designed, produced, and screened in vitro for activity at the somatostatin (sst(1-5)) and melanin-concentrating hormone (MCH(1)) receptors. Bioactive compounds were found for each target, with specific chemoform preferences identified in each case, which can be used to guide follow-on drug discovery projects without the need for scaffold hopping.