Low Molecular Weight Antagonists of the Myelin-Associated Glycoprotein: Synthesis, Docking, and Biological Evaluation

The Injured adult mammalian central nervous system Is all inhibitory environment for axon regeneration due to specific inhibitors,among them the myelin-associated glycoprotein (MAG), a member of the Siglec family (sialic-acid binding immunoglobulin-like lectin). In earlier Studies, we identified the lead structure5, which shows a 250-fold improved in vitro affinity for MAG compared to the tetrasaccharide binding epitope of GQ1b alpha (1), the best physiological MAG ligand described so far. By modifying the 2- and 5-position, the affinity of 5 could be further improved to the nanomolar range (-> 19a). Docking Studies to a homology model of MAG allowed the rationalization of the experimental binding properties. Finally, pharmacokinetic parameters (stability in the cerebrospinal fluid, logD and Permeation through the BBB) indicate the drug-like properties of the high-affinity antagonist 19a.