Anti-Naegleria fowleri and Anti-Balamuthia mandrillaris Activities of Propolis

Aim: Herein, we determined the anti-amoebic properties of propolis collected from different regions in Iran against Naegleria fowleri and Balamuthia mandrillaris. Background: Natural products remain a valuable source of compounds that are biologically active. Approximately one-third of well-known therapeutic drugs worldwide are derived from natural products. Objectives: Considering the use of propolis in folk medicine, here, for the first time, we evaluated anti-amoebic properties of propolis against free-living pathogenic amoebae, B. mandrillaris and N. fowleri. Methods: Propolis was collected from different regions of Iran and ethanolic extracts were prepared. Amoebicidal and cysticidal assays were accomplished to determine the effects of propolis against N. fowleri and B. mandrillaris. In vitro cytotoxicity assays were carried out to establish propolis effects on host cell damage. Finally, propolis metabolites were determined using spectrometric methods. Results: It was observed that propolis exhibited potent antiamoebic effects against trophozoites and cysts of both N. fowleri and B. mandrillaris at μg concentrations. When tested against cysts of both amoebae, only selected propolis exhibited cysticidal properties. The best activity was observed by propolis from the Kermanshah region, which depicted more than 95% amoebicidal activity and more than 60% cysticidal activity against both amoebae, respectively. Liquid chromatography- tandem mass spectrometry revealed that each extract is comprised of various components. Conclusion: For the first time, we showed that propolis has amoebicidal activity against both amoebae tested. Investigation into the individual activity of the components of propolis extracts and their mechanism of action against the aforementioned parasites might lead to the discovery of novel anti-amoebic compounds.