Effects of Cinnamaldehyde on the Cell Wall of A. fumigatus and Its Application in Treating Mice with Invasive Pulmonary Aspergillosis.

Background: The invasive pulmonary aspergillosis is a kind of high incidence of disease with difficulties in treatment, poor prognosis, and high mortality.

Objectives: The study aimed to reveal the effect of cinnamaldehyde on the fungal cell wall and verify its efficacy on invasive pulmonary aspergillosis on immunosuppressed Institute of Cancer Research mice (ICR mice).

Methods: ICR mice were given cyclophosphamide 200 mg.kg-1 . d-1 by intraperitoneal injection for 2 days. On the 4th day, the mice were given 50 μL of Aspergillosis fumigatus spore (107 colony form unit CFU/mL) by intranasal injection to establish immunosuppressive animal models with invasive Aspergillosis fumigatus infection. Then the mice in treatment group orally administered cinnamaldehyde for 14 consecutive days, while voriconazole was given to the mice in the positive control group.

Results: The clearance rate of pulmonary fungi, cure rate, and reduction of 1,3- β - D -glucans in treatment group were 80.00%, 80.00%, and 81.00%, respectively while in positive control group they were 67.00%, 60.00%, and 62.00%, respectively. There were significant differences in the results between two groups as mentioned above (P<0.05). Electron microscopy showed that, in treatment group, the cell wall of Aspergillus fumigatus was dissolved and detached and the cell surface was incomplete. There were edema, degeneration, and necrosis in nucleus and organelle, which lead to cellular necrocytosis. The cytomembrane of Aspergillus fumigatus was intact, clear, and complete, whereas the cytomembrane in the positive control group disappeared. The hyphal morphology of Aspergillus fumigatus was deformed, but the cell wall was intact.

Conclusion: Cinnamaldehyde has a good curative effect in the treatment of invasive pulmonary aspergillus infection in immunodeficient mice. It mainly affects the synthesis of 1,3- β - D -glucans from the cytoderm of Aspergillus fumigatus but does not affect cell wall. It would potentially be an effective and novel drug for targeted treatment of Aspergillus fumigatus deep infection.