Hexa-D-arginine is an inhibitor of furin.
Hexa-D-arginine (10 μM) protects against the cytotoxic effects of anthrax toxin in RAW 264.7 cells. The concentrations of Hexa-D-arginine requires to block the cleavage of PA are similar to those required to inhibit toxicity[2].
Administration of hexa-d-arginine to PEA-treated mice significantly improves their survival rate and also decreases circulating levels of tumor necrosis factor alpha[1]. Rats treated with the combination of anthrax toxins and Hexa-D-arginine exhibit a 40% survival rate at 5 h compared with a control group treated solely with anthrax toxin (0% survival rate). Administration of Hexa-D-arginine (1 mg/100 μL) also results in a considerable delay in the onset of anthrax toxemia compared with results of the control group treated solely with anthrax toxin[2].
References:
[1]. Sarac MS, et al. The furin inhibitor hexa-D-arginine blocks the activation of Pseudomonas aeruginosa exotoxin A in vivo. Infect Immun. 2002 Dec;70(12):7136-9.
[2]. Sarac MS, et al. Protection against anthrax toxemia by hexa-D-arginine in vitro and in vivo. Infect Immun. 2004 Jan;72(1):602-5.