Galectin-3-Binding Glycomimetics that Strongly Reduce Bleomycin-Induced Lung Fibrosis and Modulate Intracellular Glycan Recognition.

Discovery of glycan-competitive galectin-3-binding compounds that attenuate lung fibrosis in a murine model and that block intracellular galectin-3 accumulation at damaged vesicles, hence revealing galectin-3-glycan interactions involved in fibrosis progression and in intracellular galectin-3 activities, is reported. 3,3'-Bis-(4-aryltriazol-1-yl)thiodigalactosides were synthesized and evaluated as antagonists of galectin-1, -2, -3, and -4 N-terminal, -4 C-terminal, -7 and -8 N-terminal, -9 N-terminal, and -9 C-terminal domains. Compounds displaying low-nanomolar affinities for galectins-1 and -3 were identified in a competitive fluorescence anisotropy assay. X-ray structural analysis of selected compounds in complex with galectin-3, together with galectin-3 mutant binding experiments, revealed that both the aryltriazolyl moieties and fluoro substituents on the compounds are involved in key interactions responsible for exceptional affinities towards galectin-3. The most potent galectin-3 antagonist was demonstrated to act in an assay monitoring galectin-3 accumulation upon amitriptyline-induced vesicle damage, visualizing a biochemically/medically relevant intracellular lectin-carbohydrate binding event and that it can be blocked by a small molecule. The same antagonist administered intratracheally attenuated bleomycin-induced pulmonary fibrosis in a mouse model with a dose/response profile comparing favorably with that of oral administration of the marketed antifibrotic compound pirfenidone.

1H-1,2,3-triazol-1-yl thiodigalactoside derivatives as high affinity galectin-3 inhibitors.

Galactose C3-triazole derivatives were synthesized by Cu(I)-catalyzed cycloaddition between acetylenes and galactose C3-azido derivatives. Evaluation against galectin-3, 7, 8N (N-terminal) and 9N (N-terminal) revealed 1,4-disubstituted triazoles to be high-affinity inhibitors of galectin-3 with selectivity over galectin-7, 8N, and 9N. Conformational analysis of 1,4-di- and 1,4,5-tri-substituted galactose C3-triazoles suggested that a triazole C5-substituent interfered sterically with the galectin proteins, which explained their poor affinities compared to the corresponding 1,4-disubstituted triazoles. Introduction of two 1,4-disubstituted triazole moieties onto thiodigalactoside resulted in affinities down to 29 nM for galectin-3.

Scalable synthesis of L-iduronic acid derivatives via stereocontrolled cyanohydrin reaction for synthesis of heparin-related disaccharides.

L-ido cyanohydrin 3 was prepared from diacetone-D-glucose in four steps and 76% overall yield and 90% de via cyanohydrin reaction of aldehyde 2. This process can be scaled to provide >1 mol of pure L-ido cyanohydrin 3. Cyanohydrin 3 was elaborated to 1,2-isopropylidine-protected L-ido nitrile (8), iduronic amide 9, and known carboxy ester 10. Coupling of 8 and 9 with glucosamine donors leads to new types (6-cyano and 6-carboxamide) of heparin-related disaccharides.

3-(1,2,3-Triazol-1-yl)-1-thio-galactosides as small, efficient, and hydrolytically stable inhibitors of galectin-3.

Copper(I)-catalyzed addition of alkynes to methyl 3-azido-3-deoxy-1-thio-beta-D-galactopyranoside afforded stable and structurally simple 3-deoxy-3-(1H-1,2,3-triazol-1-yl)-1-thio-galactosides carrying a panel of substituents at the triazole C4 in high yields. The 3-(1H-[1,2,3]-triazol-1-yl)-1-thio-galactoside collection synthesized contained inhibitors of the tumor- and inflammation-related galectin-3 with Kd values as low as 107 microM, which is as potent as the natural disaccharide inhibitors lactose and N-acetyllactosamine.