E 64c

E 64c is a derivative of naturally occurring epoxide inhibitor of cysteine proteases, a Calcium-activated neutral protease (CANP) inhibitor and a very weak irreversible cathepsin C inhibitor. E 64c exhibits entry-blocking effect for MERS-CoV. IC50 & Target: Cysteine proteases^[1], CANP^[2], Cathepsin C^[3]. In Vitro: E-64c, a derivative of naturally occurring epoxide inhibitor of cysteine proteases, with papain; especially with regard to the hydrogen bonding and hydrophobic interactions of the ligands with conserved residues in the catalytic binding site^[1]. E 64c (k₂/K_i=140±5M^-1s^-1) is demonstrated to be a lead structure for the development of irreversible cathepsin C inhibitors^[3]. In Vivo: The t-1/2 of plasma E-64c is 0.48 hours. The hemodynamic effects of E-64c are absent at this dose. Using two way analysis of variance, the effects of reperfusion (p=0.0016) or E-64c (p=0.0226) per se on infarct size are significant. In comparing Group A with Group B and Group C with Group D, the depletion of CPK in the E-64c treated groups (Groups A and C) is slightly less than in the vehicle-injected groups (Groups B and D). The insufficient effect of E-64c alone may be explained by the early administration and relatively short t-1/2. Since the effectiveness of NCO-700 has been established,6),7) our findings might indicate a small but beneficial effect of E-64c on infarct size and CPK content^[2].