Eucalyptus oil reduces allergic reactions and suppresses mast cell degranulation by downregulating IgE-FcεRI signalling

Eucalyptus oil has traditionally been used for bactericidal, anti-inflammatory, analgesic, and sedative effects. Building on reports that it suppresses chemokines, cytokines, and lipid mediators in immune cells, this study tested whether Eucalyptus oil can be used for allergic dermatitis using a mouse IgE-mediated local allergic model. Topical Eucalyptus oil suppressed edema and vascular hyperpermeability in IgE-mediated skin reactions. Mast cell degranulation was inhibited, and the main component 1,8-cineole was examined for effects on signalling. 1,8-cineole suppressed mast cell degranulation and inhibited phosphorylation of PLCγ and p38, indicating it acts directly or indirectly on IgE–FcεRI downstream signalling to reduce allergic responses.

Tomoya Nakamura, Naoki Yoshida, Yu Yamanoi, Akira Honryo, Hiroyuki Tomita, Hiroki Kuwabara, Yoshihiko Kojima