Insecticidal activity and mechanism of cinnamaldehyde in C. elegans

Cinnamon is the dried bark of Cinnamomum cassia Presl, and its main component is cinnamaldehyde (CA). Decades of synthetic pesticide use to control parasitic nematodes that can harm plants has seriously polluted the environment and poses a risk to soil ecology, highlighting the need to develop natural biological pesticides. Some species classified under Nematoda are highly similar, therefore we used the model organism C. elegans to explore the effect of cinnamaldehyde, a plant-derived natural product, on C. elegans viability. We found that the lethal dose of cinnamaldehyde for C. elegans treatment for 4 h at a concentration of 800 mg/L. Sequencing-based transcriptome data revealed differences between the cinnamaldehyde treatment and control groups. RNA-seq analysis showed that C. elegans exposed to cinnamaldehyde had significantly altered expression of metabolic genes, particularly for genes involved in glutathione metabolism (gst-1, gst-2, gst-4, gst-5, gst-6, gst-7, gst-8, gst-25, gst-30, gst-38, gst-44, and gcs-1). Therefore, glutathione metabolism is altered in C. elegans upon exposure to cinnamaldehyde. Based on the above results, treatment with 800 mg/L of cinnamaldehyde for 4 h was selected for all experiments in nematodes. Given these findings, cinnamaldehyde may be a promising natural alternative to synthetic pesticides for controlling plant parasitic nematodes with low cost, high efficiency, and diminished environmental pollution.