Antifungal Activity of Cinnamaldehyde Against Fusarium sambucinum Involves Inhibition of Ergosterol Biosynthesis.

In this study, the antifungal effect of cinnamaldehyde against Fusarium sambucinum and its underlying mechanisms were determined.

Minimum inhibitory concentration and minimal fungicidal concentration of cinnamaldehyde were 3 and 4 mmol l^-1 on spore germination and colony development assays in vitro, respectively. Furthermore, the lesion diameter of potato tubers and tuber slices inoculated with F. sambucinum was reduced by 76.9% and 69% after treatment with 4 mmol l^-1 cinnamaldehyde. Cytometric analyses reveled that cinnamaldehyde significantly affected the integrity of cell membrane firstly, then decreased mitochondrial membrane potential and induced the accumulation of intracellular reactive oxygen species. Meanwhile, High performance liquid chromatography (HPLC) results indicated that 3 mmol l^-1 cinnamaldehyde could reduce the ergosterol content by 67.94%. This effect was accompanied by a down regulation of ERG11, ERG6 and ERG4 which were involved in ergosterol biosynthesis.

Theses results suggest that cinnamaldehyde exerts strong antifungal activity against F. sambucinum, probably by affecting the ergosterol biosynthetic processes what leads to the disruption of cell membrane integrity.Cinnamaldehyde is a predominant constituent and key flavor compound of cinnamon essential oil. It has been used as a food additive and flavorant. It is expected to be a novel and safe fungicide for controlling dry rot in potato tubes.