Design, synthesis, And applications of galectin modulators in human health

Over the last decade, the family of galectin proteins has been identified as key regulators of important biological processes. They bind β-D-galactopyranoside residues in glycoconjugates, and by presenting multiple binding sites, within one galectin or by forming dimers or multimers, they can cross-link glycoproteins and form galectin-glycoprotein lattices. Such lattices formed on the cell surface or in vesicles have been shown to control, for example, surface residence time and signaling by receptors. Hence, compounds modulating galectin binding to their glycoprotein ligands are of potential clinical interest. This chapter describes the design and development of disubstituted thiodigalactoside derivatives that form optimal interactions with the galectin-3 binding site resulting in double-digit nanomolar affinities. Studies are discussed in which such galectin-3-modulating compounds have been important in elucidating galectin-3 mechanisms, including galectin-3 trafficking, cancer, inflammation, fibrosis, and angiogenesis. Medically relevant models using the galectin-3 modulators in characterizing macrophage alternative activation and chronic inflammation, myofibroblast activation and fibrosis, and ocular angiogenesis are discussed in more detail. In summary, the high galectin-3 affinity and definitive effects in relevant models of the disubstituted thiodigalactosides identify them as promising as lead compounds for drug development, albeit leaving a challenge in terms of optimizing PK/ADME properties.