Novel non-covalent thrombin inhibitors incorporating P(1) 4,5,6,7-tetrahydrobenzothiazole arginine side chain mimetics

The design, synthesis and biological activity of a series of novel non-covalent D-Phe-Pro-Arg motif-based thrombin inhibitors incorporating 4,5,6,7-tetrahydrobenzothiazol-2-amine as a novel arginine surrogate are described. Compound 9, the most potent in the series of thrombin inhibitors, exhibited an in vitro K(i) of 128 nM and 342-fold selectivity against trypsin. The binding mode of this novel class of thrombin inhibitors in the enzyme active site, based on the X-ray crystal structure of compound 9 co-crystallized with human alpha-thrombin, is discussed.