Amoebicidal activity of α-bisabolol, the main sesquiterpene in chamomile (Matricaria recutita L.) essential oil against the trophozoite stage of Acanthamoeba castellani Neff.

Acanthamoeba genus includes opportunistic pathogens which are distributed worldwide and are causative agents of a fatal encephalitis and severe keratitis in humans and other animals. Until present there are not fully effective therapeutic agents against this pathogen and thus the need to search for novel anti-amoebic compounds is urgent. Recently, essential oils of aromatic and medicinal plants have shown activity against Acanthamoeba strains. Therefore, this study was aimed to evaluate the activity of main component of chamomile essential oil (a sesquiterpene) namely α-bisabolol against the Acanthamoeba castellani Neff strain. After evaluation of the activity and toxicity of this molecule, IC50 values of 20.839 ± 2.015 for treated amoebae as well as low citotoxicty levels in a murine macrophage cell line was observed. Moreover, in order to elucidate mechanism of action of this molecule, changes in chromatin condensation levels, permeability of the plasmatic membrane, the mitochondrial membrane potential and the ATP levels in the treated amoebic strains were checked. The obtained results revealed that α-bisabolol was able to induce apoptosis, increase the permeability of the plasmatic membrane and decrease both mitochondrial and ATP levels in the treated amoebae. Therefore, and given the obtained results, α-bisabolol could be used a future therapeutic agent against Acanthamoeba infections.