Development of antimicrobials against Acanthamoeba

Abstract

Acanthamoeba is a free-living amoeba widely distributed in the environment which exists as two stages in their life cycle: a motile and trophic replicating trophozoite and a resistant cyst stage. In recent years, the incidence of infections due to Acanthamoeba spp. has shown a remarkable increase. This parasite is the causative agent of a sight-threatening infection of the cornea known as Acanthamoeba keratitis (AK) and a fatal disease of the central nervous system known as Granulomatous Amebic Encephalitis (GAE) mainly in immunocompromised patients. Although the trophozoite form is much more readily eliminated, at present there are not harmless effective treatments or a single drug that can eliminate both cystic and trophozoite forms. A particular set of compounds known as Minor Grove Binders (MGBs) have the characteristic of binding specifically to minor groove region of double-stranded DNA. The main effects of these MGBs are their ability to interfere with biological functions of DNA such as transcription machinery, also induction of apoptosis, hence cell death. These molecules have received great attention since they can be empirically screened and iteratively refined via chemical synthesis to target various entities such as tumors, bacteria, viruses and parasites. MGBs have been tested in vitrousing a colorimetric alamar Blue viability cell assayagainst Acanthamoeba castellanii Neff strain. To date, 2 hit compounds were able to inhibit trophozoites producing IC50s of 1.56 µM and 12.5 µM.