Amoebicidal activity of caffeine and maslinic acid by the induction of Programmed Cell Death in Acanthamoeba

Free living amoebae of the genus Acanthamoeba are the causal agents of a sight threatening ulceration of the cornea called Acanthamoeba keratitis, and the rare but usually fatal granulomatous amoebic encephalitis. Although there are many therapeutic options for the treatment of Acanthamoeba infections, they are generally lengthy and/or have limited efficacy. For the best clinical outcome, the treatments should target both the trophozoite and the cyst stages as the later are known to confer resistance to treatment. In this study we document the activity of caffeine and maslinic acid against both the trophozoite and the cyst stages of three clinical strains of Acanthamoeba These drugs were chosen because they are reported to inhibit glycogen phosphorylase which is required for encystation. Maslinic acid is also reported to be an inhibitor of extracellular proteases which may be relevant since the protease activity of Acanthamoeba is correlated with their pathogenicity. We also provide evidence or the first time that both drugs exert their anti-amoebal effects through programmed cell death.