Eucalyptus Oil

EUCALYPTUS OIL

Synonyms

Eucalyptus, Stringy Bark Tree, Blue gum, Blue Gum Tree.

Biological Source

Eucalyptus oil is the essential oil obtained by the distillation of fresh leaves of Eucalyptus globulus and other species like E. polybractea, E. viminalis, and E. smithii, belonging to family Myrtaceae.

Geographical Source

It is mainly found in Australia, Tasmania, United States, Spain, Portugal, Brazil, North and South Africa, India, France, and Southern Europe.

History

Eucalyptus globulus has been used since a long time for intermittent fever. The leaves and their preparations have been successfully used as a tonic, stimulant, stomachic, in dyspepsia, in catarrh of the stomach, in typhoid fever, in asthma, in whooping cough, etc. More recently it has been recommended as a diuretic in the treatment of dropsy.

Characteristics

Eucalyptus is a tall, evergreen tree, the trunk, which grows to 300 feet high or more, 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 and white, without any petals.

Eucalyptus oil is a colourless or straw-coloured fluid, with a characteristic odour and taste, soluble in its own weight of alcohol. According to the British Pharmacopoeia Eucalyptus oil should contain not less than 55%, by volume of Eucalyptol, have a specific gravity 0.910 to 0.930, and optical rotation –10 degrees to 10 degrees.

Microscopy

Eucalyptus leaf is isobilateral. Stomata are of anomocytic type and sunken, on both surfaces. Epidermal cells are polygonal with thick cuticle; anticlinal walls are straight on both surfaces. There are three to four layers of elongated palisade cells below each epidermis. Between these palisade regions, two to three layers of spongy parenchyma occur and some of its cells contain cluster and prismatic calcium oxalate crystals. Palisade regions exhibit large subglobular oleoresin cavities. The midrib region shows no collenchymatous cells. Transverse section through the midrib region shows nearly uninterrupted arc of lignified pericyclic fibres just outside the vascular bundle.

                   T.S. (schematic) of eucalyptus leaf

Chemical Constituents

Eucalyptus oil contains volatile oil of which 70 to 85% is 1,8-cineole also known as eucalyptol. The other constituents present are p-cymene, α-pinene; small quantity of sesquiterpenes like ledol, aromadendrene; aldehydes, ketones, and alcohols. It also has polyphenolic acids like ferulic acid, caffeic acid, gallic acid; flavonoids such as eucalyptin, hyperoside and rutin.

Uses

The oil is used as stimulant, antiseptic, flavouring agent, aromatic, deodorant, expectorant, antimicrobial, febrifuge, diuretic, and antispasmodic. It is also used in the treatment of lung diseases, sore throat, cold, as a vapour bath for asthma and various respiratory ailments and in bronchitis.

Marketed Products

It is one of the ingredients of the preparations known as Cold Balm, Muscle and Joint Rub, Canisep, Erina-EP, Scavon Vet. (Himalaya Drug Company).