Cl-amidine is an orally active inhibitor of peptidyl arginine deiminase (PAD) with IC50 values of 0.8 μM, 6.2 μM, and 5.9 μM for PAD1, PAD3, and PAD4, respectively. It induces apoptosis in cancer cells.

PAD4:5.9 μM

Cl-amidine inhibits all the active PAD isozymes with near equal potency (kinact/KI=13,000/(M?min) for PAD4) [1]. Cl-amidine (0, 5, 10, 15, 20, 25, 50 μg/mL, 24 hours) induces apoptosis in TK6 lymphoblastoid cells and HT29 colon cancer cells in a dose-dependent manner. Interestingly, the colon cancer cell line (HT29) is relatively resistant to apoptosis caused by Cl-amidine [2]. Cl-amidine irreversibly inactivates PADs by covalently modifying an active site cysteine that is important for its catalytic activity [4].

Cl-amidine (75 mg/kg, i.p. once daily) suppresses and treats DSS-induced colitis in mice, and administered via oral gavage (5, 25, 75 mg/kg, once daily), it significantly reduces histology scores in a dose-dependent manner [2].