Abstract
FUT-175 (6-amidino-2-naphthyl 4-guanidino benzoate,) a new synthetic protease inhibitor, inhibits the enzyme activities of various proteases, such as Clr, Clesterase, thrombin, kallikrein, plasmin and trypsin. FUT-175 strongly inhibited complementmediated hemolysis via the classical and alternative pathway. The concentrations of FUT-175 required for 50% inhibition of complement-mediated hemolysis by the classical and alternative pathway were 6.9×10-8M and5.1×10-7M, respectively. The effects of FUT-175 on various immunological reactions in vivo were studied. The minimal effective dose of FUT-175 in systemic Forssman shock in guinea pigs were 12.5mg/kg i. p, and 50mg/kg p.o. In passive Arthus reactions in rats, the effective concentration were 25mg/kg i. p.and 250mg/kg p.o. FUT-175 also improved other immunological reactions, such as passive cutaneous anaphytaxis and delayed hypersensitivity. Furthermore, at a dose of 25mg/kg i. p.it strongly protected mice from death by endotoxin shock.
