1,8-cineole is a natural
monoterpene, also known as
eucalyptol. It is a major compound of many plant
essential oils, mainly extracted from
Eucalyptus globulus oil. As an isolated compound,
1,8-cineole is known for its
mucolytic and
spasmolytic action on the respiratory tract, with proven clinical efficacy.
1,8-cineole has also shown therapeutic benefits in inflammatory airway diseases, such as
asthma and
chronic obstructive pulmonary disease (
COPD). This clinical evidence refers to its anti-inflammatory and
anti-oxidant mode of action, which has been proven in numerous pre-clinical studies. In vitro studies found strong evidence that
1,8-cineole controls inflammatory processes and mediator production of
infection- or
inflammation-induced mucus hypersecretion by its action as anti-inflammatory modifier rather than a simple
mucolytic agent. The aim of this review is to present these preclinical studies performed with the pure
monoterpene, and to summarize the current knowledge on the mode of action of
1,8-cineole. The actual understanding of the pure
1,8-cineole compared to mixtures of natural
volatile oils containing
1,8-cineole as a major compound and to mixtures of natural
terpenes, known as
essential oils, will be discussed. Based on the anti-oxidative and anti-inflammatory properties, recent clinical trials with
1,8-cineole have shown first evidence for the beneficial use of
1,8-cineole as long-term
therapy in the prevention of
COPD-exacerbations and to improve
asthma control.