Components of Volatile Fractions from Eucalyptus camaldulensis Leaves from Iraqi–Kurdistan and Their Potent Spasmolytic Effects

Inhalation of vapors from a hot tea of Eucalyptus camaldulensis Dehnh. leaves is considered by Iraqi–Kurdistan people an effective spasmolytic and antipyretic remedy for the treatment of respiratory diseases. The constituents of volatile fractions isolated by hydrodistillation from dried leaves of the plant collected in Kurdistan were determined by GC-FID and GC-MS analyses. More than 90% components were identified. The most abundant constituents were 1,8-cineole, p-cymene, α-pinene, terpinen-4-ol, aromadendrene, and α-terpineol. The different volatile fractions induced relaxation on rat isolated aortic and tracheal rings in concentration-dependent manner. These effects appeared to be due to a complex interaction between various terpenoid components rather than being only due to the main oil constituent, 1,8-cineole. The KCa channel and the NO pathway were not significantly involved in the relaxation mechanism, while Ca(2+) channels played a major role in the spasmolytic effects.