Effect of Cinnamaldehyde and Its Nanoemulsion on Acanthamoeba castellanii Cysts and Trophozoites.

Purpose: The current study aimed to investigate the trophocidal and cysticidal activities of cinnamaldehyde (Cinn), a natural compound with known antimicrobial properties, against environmental and reference strains of Acanthamoeba castellanii. Additionally, we explored the potential benefits of Cinn formulated as a nanoemulsion (Cinn-NE) in enhancing its efficacy.

Methods: Cinn-NE was prepared using the ultrasonic emulsification method. The amoebicidal effect of Cinn was evaluated against both trophozoites and cysts of reference and environmental strains of Acanthamoeba, along with an assessment of whether nanotechnology enhances this effect.

Results: Our results demonstrated that Cinn exhibited strong activity against both trophozoites and cysts of Acanthamoeba. Importantly, Cinn-NE showed enhanced activity compared to pure Cinn, possibly due to increased surface area and improved interaction with microbial membranes. In this study, the difference in susceptibility to Cinn and Cinn-NE between the environmental and the reference strain of A. castellanii was observed. Acanthamoeba cysts were more resistant to the effects of Cinn or Cinn-NE than trophozoites. Additionally, we found that nutrient availability in the medium influenced the susceptibility of Acanthamoeba to Cinn and Cinn-NE. A nutrient-deficient medium reduced their vulnerability to destruction, suggesting a role for nutrient availability in the response of Acanthamoeba to antimicrobial agents.

Conclusion: In conclusion, our study highlights the potential of Cinn and Cinn-NE as effective agents for combating Acanthamoeba infections. Further research is needed to elucidate the specific mechanisms underlying the differential susceptibility to Cinn, optimize its use as a treatment or surface disinfectant, and explore Acanthamoeba's cellular and molecular responses to nutrient availability.