Aryl O- and S-galactosides and lactosides as specific inhibitors of human galectins-1 and -3:: Role of electrostatic potential at O-3

Phase transfer catalyzed reaction was used for the high yielding synthesis of aryl 1-thio-beta-D-galacto- and lacto-pyranosides carrying a panel of substituents on the phenyl groups. Best galectin-1 inhibitors were simple p-nitrophenyl thiogalactoside 5a for the monosaccharide and o-nitrophenyl thiolactoside 6f or napthylsulfonyl lactoside 8c, both being 20 times better relative to natural ligands. Relative inhibitory properties as low as 2500 and 40 mu M were observed, respectively. The electronic effects of the lactoside aglycons directly influenced the electrostatic potential at O-3, which was associated with the inhibitory potencies against galectin-1. (C) 2006 Elsevier Ltd. All rights reserved.