Strong Binding of C -Glycosylic1,2-Thiodisaccharides to Galectin-3─Enthalpy-Driven Affinity Enhancement by Water-Mediated Hydrogen Bonds.
Lazar, L., Tsagkarakou, A.S., Stravodimos, G., Kontopidis, G., Leffler, H., Nilsson, U.J., Somsak, L., Leonidas, D.D.(2023) J Med Chem 66: 12420-12431
- PubMed: 37658813 
- DOI: https://doi.org/10.1021/acs.jmedchem.3c00882
- Primary Citation of Related Structures:  
8OJI, 8OJK, 8OJM, 8OJO, 8PPN - PubMed Abstract: 
Galectin-3 is involved in multiple pathways of many diseases, including cancer, fibrosis, and diabetes, and it is a validated pharmaceutical target for the development of novel therapeutic agents to address unmet medical needs. Novel 1,2-thiodisaccharides with a C -glycosylic functionality were synthesized by the photoinitiated thiol-ene click reaction of O -peracylated 1-C-substituted glycals and 1-thio-glycopyranoses. Subsequent global deprotection yielded test compounds, which were studied for their binding to human galectin-3 by fluorescence polarization and isothermal titration calorimetry to show low micromolar K d values. The best inhibitor displayed a K d value of 8.0 μM. An analysis of the thermodynamic binding parameters revealed that the binding Gibbs free energy (Δ G ) of the new inhibitors was dominated by enthalpy (Δ H ). The binding mode of the four most efficient 1,2-thiodisaccharides was also studied by X-ray crystallography that uncovered the unique role of water-mediated hydrogen bonds in conferring enthalpy-driven affinity enhancement for the new inhibitors. This 1,2-thiodisaccharide-type scaffold represents a new lead for galectin-3 inhibitor discovery and offers several possibilities for further development.
Organizational Affiliation: 
Department of Organic Chemistry, University of Debrecen, P.O. Box 400, H-4002 Debrecen, Hungary.