A Breath of Fresh Air for Eucalyptus Research

A new study by Dr. Sven-Eric Jordt’s Chemical Sensing, Pain and Inflammation Research Laboratory at Duke Anesthesiology identifies the mechanism through which eucalyptol, the active ingredient in eucalyptus oil, suppresses inflammation.

Eucalyptol, a cooling natural product, is licensed as an over-the-counter treatment in some countries, either as a pill, in lozenges, as an oil for inhalation, or as a cream for pain treatment. Eucalyptol is also found in sage, rosemary and tea tree oil, all used for treatment of inflammation. Clinical trials suggested that eucalyptol is effective as a supportive treatment in bronchitis and chronic obstructive pulmonary disorder, a lung disease caused by smoking. However, eucalyptol’s mechanism of action has remained unclear, and studies in mice and rats required much higher amounts of eucalyptol to be effective than in the human studies.

This study, titled “TRPM8 mediates the anti-inflammatory effects of eucalyptol,” is published in the February 2017 issue of the British Journal of Pharmacology. It identifies a target for eucalyptol and explains why eucalyptol might be more effective in humans.

“We identified TRPM8 as eucalyptol’s target to treat skin and lung inflammation” says Dr. Jordt. “TRPM8 is a sensor for cooling in temperature-sensing nerves in the body. Eucalyptol mimics the sensation of cooling that is known to have anti-inflammatory effects. We also found that TRPM8 in humans is more sensitive to eucalyptol than in the mouse or rat. This may explain why lower amounts of eucalyptol were effective in the published human trials.”

This Duke study provides a rationale for additional human studies testing this widely-used natural product in other inflammatory conditions, and for the development of novel eucalyptol-based drugs. Duke Anesthesiology researchers, Ana Caceres, Boyi Liu, Sairam Jabba and Satya Achanta, contributed to the study. Dr. Jordt is an associate professor in anesthesiology and a faculty member of the department’s newly established Center for Translational Pain Medicine. His research interests focus on the mechanisms that enable humans and animals to sense touch, pain and irritation.