FK706 is a slow-binding and competitive human neutrophil elastase inhibitor (IC50: 83 nM; Ki: 4.2 nM). FK706 also inhibits mouse neutrophil elastase and porcine pancreatic elastase (IC50s: 22 nM and 100 nM, respectively). FK706 has an anti-inflammatory effect.

Pancreatic elastase (porcine):100 nM, Neutrophil elastase (mouse):22 nM, Neutrophil elastase (human):（ki）4.2 nM, Neutrophil elastase (human):83 nM

FK706 effectively inhibits the hydrolysis of bovine neck ligament elastin (2 mg/mL final concentration) by human neutrophil elastase (4 μg/mL final concentration) (IC50: 230 nM) [1]. FK706 blocks the release of inflammatory chemokines, suppresses the expression of IL-8 and MCP-1 mRNA, and suppresses NF-κB activation. FK706 may directly block human lung fibroblasts activation of NF-κB, preventing the expression of inflammatory chemokines during cigarette smoke-induced lung inflammation [2].

FK706 (10-100 mg/kg; subcutaneous injection; for 1-6 hours; male C57BL mice) treatment obviously inhibits human neutrophil elastase (20 μg/paw)-induced paw edema in mice. It shows a dose-dependent manner (47% inhibition at a dose of 100 mg/kg) [1].