BACKGROUND: Previous studies suggested that
essential oils suppressed the adherence response of human neutrophils in vitro and that intraperitoneal application of geranium oil suppressed the neutrophil accumulation into peritoneal cavity in vivo. Usually,
essential oils are applied through skin in
aromatherapy in inflammatory symptoms. The purpose of this study is to assess the effects of cutaneous application of
essential oils on the accumulation of neutrophils in inflammatory sites in skin of mice. METHODS:
Inflammation with accumulation of inflammatory cells was induced by injection of
curdlan, a (1-->3)-beta-
D-glucan in skin or peritoneal cavity of mice.
Essential oils were applied cutaneously to the mice immediately and 3 hr after
intradermal injection of
curdlan. The skin with inflammatory lesion was cut off 6 hr after injection of
curdlan, and the homogenates were used for
myeloperoxidase (MPO: a marker
enzyme of neutrophil granule) assay. RESULTS: The MPO activity of the skin lesion induced by
curdlan was suppressed dose-dependently by cutaneous application of geranium oil. Other
oils such as lavender, eucalyptus and
tea tree
oils also suppressed the activity, but their activities seemed weaker than geranium. Juniper oil didn't suppress the activity CONCLUSION: Cutaneous application of
essential oils, especially geranium oil, can suppress the inflammatory symptoms with neutrophil accumulation and
edema.