CHF-6333 xinafoate is a neutrophil elastase (NE) inhibitor with an IC50 of 0.21 nM and a KD of 0.16 nM. It exhibits activity against both human (IC50= 0.22 nM) and rat (IC50= 3.63 nM) proteases and also inhibits proteinase 3 with an IC50 of 22 nM. This compound is applicable in bronchiectasis (BE) research.

CHF6333 (Compound 15) xinafoate exhibits a half-life (t1/2) exceeding 240 minutes in both human and rat liver microsomes at 1 μM concentration over 0-30 minutes. The binding rate to human plasma proteins is 60.0%, and to rat plasma proteins is 58.0% at a concentration of 10 μM for 4 hours. After a 1-hour incubation in mouse or human lung S9 fractions at 1 μM, over 80% of CHF6333 xinafoate remains unmetabolized. It has an IC50 greater than 10 μM for all CYP450 isoenzymes, including CYP1A1, CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP3A5. The IC50 for acetylcholinesterase is 24.7 μM， while it is greater than 100 μM for M2 receptors and 67.3 μM for M3 receptors. At 100 μM, CHF6333 xinafoate does not inhibit the hERG channel in HEK-293 cells, indicating no cardiovascular toxicity risk. Furthermore, it demonstrates no cytotoxicity at high concentrations (1-100 μM for 24 hours) in SAEC (human airway epithelial cells) and HepG2 (human liver cancer cells), showing good safety profile.

Administration of CHF6333 (0.03-0.6 mg/kg, via tracheal route, single dose) xinafoate effectively prevents lung tissue damage in rats directly induced by NE.