Pharmacological studies on a synthetic protease inhibitor, FUT-175. I. Effects on complements and kallikrein.

Abstract

FUT-175 has been reported by S.Fujii et al.1) to inhibit strongly Clr, Cls, trypsin and thrombin as well as kallikrein and plasmin. In the present study, effects of FUT-175 on the complement and kallikrein system were investigated in vitro and in vivo. The in vitro complement-mediated hemolysis via classical pathway activation was performed as described by Mayer et al., and the systemic Forssman shock in guinea pigs was induced by the method of Glovsky et al. The in vitro kinin formation was performed with glass powder in rat plasma. The anti-inflammatory effects of FUT-175 were also studied on kaolin- and scald-induced edema of rat paws. FUT-175 markedly inhibited the complement-mediated hemolysis, the IC50 being 4.5 × 10−8 M, and protected the guinea pig from the systemic Forssman shock at doses of 0.3 - 3 mg/kg, i.v., in a dose-dependent manner. FUT-175 also inhibited the in vitro kinin formation with the IC50 of 1.1 × 10−7 M (glass powder) and reduced the kaolin- and scald-induced edema formation at doses of 30 - 300 mg/kg, p.o..