A tall evergreen tree native to Australia and Tasmania and cultivated elsewhere. The trunk, which can grow to over 100m, is covered with peeling, papery bark. The leaves on the young plant, up to five years old, are opposite, sessile, soft, oblong, pointed and a hoary blue colour. The mature leaves are alternate, petioled, leathery and shaped like a scimitar. The flowers are solitary, axillary and white, with no petals and a woody calyx. The fruit is a hard, four-celled, many-seeded capsule enclosed in the calyx cup.
Eucalyptus globulus Labill. (Myrtaceae).
Synonyms and Part Used
Fevertree, Gum Tree, Tasmanian Bluegum.
Eucalyptrin, hyperoside, quercetin, quercitrin and rutin.
0.5–3.5%. Eucalyptol (cineole) 70–85%. Others include monoterpenes (e.g. α-pinene, β-pinene, d-limonene,p-cymene, α-phellandrene, camphene, γ-terpinene) and sesquiterpenes (e.g. aromadendrene, alloaromadendrene, globulol, epiglobulol, ledol, viridiflorol), aldehydes (e.g. myrtenal) and ketones (e.g. carvone, pinocarvone).
Tannins and associated acids (e.g. gallic acid, protocatechuic acid), caffeic acid, ferulic acids, gentisic acid, resins and waxes.
Eucalyptus is listed by the Council of Europe as a natural source of food flavouring (leaves, flowers and preparations: category N4, with limits on eucalyptol).Both eucalyptus and eucalyptol (cineole) are used as flavouring agents in many food products.In the USA, eucalyptus is approved for food use and eucalyptol is listed as a synthetic flavouring agent.
Eucalyptus leaves and oil have been used as an antiseptic, febrifuge and expectorant.
(cineole BPC 1973) 0.05–0.2 mL.
Oil for local application:
30 mL oil to 500 mL lukewarm water.
In vitro and animal studies
Hypoglycaemic activity in rabbits has been documented for a crude leaf extract rich in phenolic glycosides.Purification of the extract resulted in a loss of activity.Expectorant and antibacterial activities have been reported for eucalyptus oil and for eucalyptol.Various Eucalyptus species have been shown to possess antibacterial activity against both Gram–positive and Gram–negative organisms. Gram–positive organisms were found to be the most sensitive, particularly Bacillus subtilis and Micrococcus glutamious.
In vitro antiviral activity against influenza type A has been documented for quercitrin and hyperoside.
Eucalyptus oil oil has been taken orally for catarrh, used as an inhalation and applied as a rubefacient.A plant preparation containing tinctures of various herbs including eucalyptus has been used successfully in the treatment of chronic suppurative otitis.The efficacy of the preparation was attributed to the antibacterial and anti–inflammatory actions of the herbs included.
Externally, eucalyptus oil is stated to be generally non–toxic, non–sensitising and non–phototoxic.Undiluted eucalyptus oil is toxic and should not be taken internally. A dose of 3.5 mL has proved fatal.Symptoms of poisoning with eucalyptus oil include epigastric burning, nausea and vomiting, dizziness, muscular weakness, miosis, a feeling of suffocation, cyanosis, delirium and convulsions.
Eucalyptus may interfere with existing hypoglycaemic therapy. Eucalyptus oil should be diluted before internal or external use.
Pregnancy and lactation
Eucalyptus oil should not be taken internally during pregnancy.
Eucalyptus is characterised by its volatile oil components. Antiseptic and expectorant properties have been attributed to the oil, in particular to the principal component eucalyptol. The undiluted oil is toxic if taken internally. Essential oils should not be applied to the skin unless they are diluted with a carrier vegetable oil.