Anti-Inflammatory Potential of Essential Oil from the Heart-Wood of the Folk Medicinal Tree Cinnamomum kanehirai Hayata in Macrophages.

Inflammation is a vital physiological response that plays a crucial role in regulating host defense against pathogens while maintaining tissue homeostasis. Inflammasomes, a family of protein complexes, are responsible for controlling the expression of pro-inflammatory cytokines IL-1β and IL-18, and they play significant roles in inflammatory responses. However, dysregulated inflammation can become a risk factor for the pathogenesis of various diseases. The discovery of anti-inflammatory substances derived from natural products represents an important strategy for new drug development. In this study, we found that the essential oil derived from the heartwood of Cinnamomum kanehirai Hayata (EOC) exhibits anti-inflammatory activities by inhibiting the NLRP3, NLRP1, NLRC4, AIM2, and non-canonical inflammasomes in macrophages. EOC also suppresses the expression of NLRP3, TNF-α, IL-6, and NO in LPS-activated macrophages. The mechanisms underlying the anti-inflammatory activity of EOC were shown to involve a reduction in reactive oxygen species production and NF-κB activation. Furthermore, terpinen-4-ol may be the key anti-inflammatory compound present in EOC. These results suggest that EOC has potential as an anti-inflammatory agent for future development.