An inhibitor of ribosome-inactivating proteins (RIPs). At a concentration of 200 mg/kg, Retro-2 displayed full protection of mice against a dose of ricin that killed 90% of an unprotected control mouse population. Blocks Leishmania parasitophorous vacuole (LPV) development. Retro-2 inhibited the replication of Leishmania parasites in axenic cultures.