PLANT DESCRIPTION
Eucalyptus is a diverse genus of flowering trees and shrubs in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia.
A mature eucalyptus may take the form of a low shrub or a very large tree. There are three main habits and four size categories that species can be divided into. Nearly all eucalyptus are evergreen but some tropical species lose their leaves at the end of the dry season. As in other members of the myrtle family, eucalyptus leaves are covered with oil glands. The copious oils produced are an important feature of the genus. The most readily recognisable characteristics of eucalyptus species are the distinctive flowers and fruit (capsules or "gumnuts"). Flowers have numerous fluffy stamens which may be white, cream, yellow, pink or red; in bud, the stamens are enclosed in a cap known as an operculum which is composed of the fused sepals or petals or both.
Some eucalyptus species have attracted attention from global development researchers and environmentalists because of desirable traits such as being fast-growing sources of wood, producing oil that can be used for cleaning and as a natural insecticide, or an ability to be used to drain swamps and thereby reduce the risk of malaria.
On warm days eucalyptus forests are sometimes shrouded in a smog-like mist of vaporised volatile organic compounds (terpenoids); the Australian Blue Mountains take their name from the haze.
Eucalyptus globulus is the principal source of Eucalyptus oil worldwide.
Eucalyptus oil
Eucalyptus oil is readily steam distilled from the leaves and can be used for cleaning and as an industrial solvent, as an antiseptic, for deodorising, and in very small quantities in food supplements, especially sweets, cough drops, toothpaste and decongestants.
It has insect repellent properties, and is an active ingredient in some commercial mosquito repellents.
Adult repellency and larvicidal activity of five plant essential oils against mosquitoes.
Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus, which has a history of wide application, as a pharmaceutical, antiseptic, repellent, flavouring, fragrance and industrial uses. The leaves of selected Eucalyptus species are steam distilled to extract eucalyptus oil.
The cineole-based oil is used as component in pharmaceutical preparations to relieve the symptoms of influenza and colds, in products like cough sweets, lozenges, ointments and inhalants. Cineole-based eucalyptus oil is used as an insect repellent and biopesticide. In the
U.S., eucalyptus oil was first registered in 1948 as an insecticide and miticide.
Eucalyptus oil is used in flavouring. Cineole-based eucalyptus oil is used as a flavouring at low levels (0.002%) in various products, including baked goods, confectionery, meat products and beverages. Eucalyptus oil has antimicrobial activity against a broad range of foodborne human pathogens and food spoilage microorganisms.
Eucalyptus oil is also used as a fragrance component to impart a fresh and clean aroma in soaps, detergents, lotions and perfumes.
Research shows that cineole-based eucalyptus oil (5% of mixture) prevents the separation problem with ethanol and petrol fuel blends. Eucalyptus oil also has a respectable octane rating and can be used as a fuel in its own right. However, production costs are currently too high for the oil to be economically viable as a fuel.
HISTORY
Australian Aboriginals use eucalyptus leaf infusions as a traditional medicine for treating body pains, sinus congestion, fever, and colds.
Dennis Considen and John White, surgeons on the First Fleet, distilled eucalyptus oil from Eucalyptus piperita found growing on the shores of Port Jackson in 1788 to treat convicts and marines. Eucalyptus oil was subsequently extracted by early colonialists, but was not commercially exploited for some time.
Baron Ferdinand von Mueller, Victorian botanist, promoted the qualities of Eucalyptus as a disinfectant in "fever districts", and also encouraged Joseph Bosisto, a Melbourne pharmacist, to investigate the commercial potential of the oil. Bosisto started the commercial eucalyptus oil industry in 1852 near Dandenong, Victoria, Australia, when he set up a distillation plant and extracted the essential oil from the cineole chemotype of Eucalyptus radiata. This resulted in the cineole chemotype becoming the generic 'oil of eucalyptus', and "Bosisto's Eucalyptus Oil" still survives as a brand.
ACTIVE MOLECULES DESCRIPTION
Eucalyptus oils in the trade are categorized into three broad types according to their composition and main end-use: medicinal, perfumery and industrial. The most prevalent is the standard cineole-based "oil of eucalyptus", a colourless mobile liquid (yellow with age) with a penetrating, camphoraceous, woody-sweet scent.
The main component of Eucalyptus oil (that ranges from the 50% to 85% of the pure extract) is the 1,8-cineole, also known as eucalyptol.
The British Pharmacopoeia states that the oil must have a minimum cineole content of 70% if it is pharmaceutical grade. The eucalyptus genus also produces non-cineole oils, including piperitone, phellandrene, citral, methyl cinnamate and geranyl acetate that are metabolically irrelevant.
Eucalyptol
Eucalyptol is a natural organic compound which is a colorless liquid. It is a cyclic ether and a monoterpenoid.
Eucalyptol is also known by a variety of synonyms: 1,8-cineol, 1,8-cineole, limonene oxide, cajeputol, 1,8-epoxy-p-menthane, 1,8-oxido-p-menthane, eucalyptol, eucalyptole, 1,3,3-trimethyl-2-oxabicyclo[2,2,2]octane, cineol, cineole.
In 1870, F.S. Cloez identified and ascribed the name eucalyptol to the dominant portion of Eucalyptus globulus oil.
Eucalyptol comprises up to 90 percent of the essential oil (the essential oil is different from the extract one, and it’s produced by the leaves of the eucalyptus) of some species, and from this oil is obtained the generic product commonly known as Eucalyptus oil. It is also found in camphor laurel, bay leaves, tea tree, mugwort, sweet basil, wormwood, rosemary, sage and other aromatic plant foliage. Eucalyptol with a purity from 99.6 to 99.8 percent can be obtained in large quantities by fractional distillation of eucalyptus oil.
Although it can be used internally as a flavoring and medicine ingredient at very low doses, typical of many essential oils (volatile oils), eucalyptol is toxic if ingested at higher than normal doses.
Eucalyptol - PubChem.
CLASSIFICATION
There are more than 700 species of eucalyptus, mostly native to Australia, and a very small number are found in adjacent areas of New Guinea and Indonesia and one, Eucalyptus deglupta, ranges north to the Philippines. Only 15 species occur outside Australia, and only 9 do not occur in Australia. Species of eucalyptus are cultivated widely in the tropical and temperate world, including the Americas, Europe, Africa, the Mediterranean Basin, the Middle East, China and the Indian Subcontinent, though most species do not tolerate frost.
INDICATIONS
Syntomatic treatment of upper respiratory tract: The cineole-based oil is used as component in pharmaceutical preparations to relieve the symptoms of influenza and colds, in products like cough sweets, lozenges, ointments and inhalants. Eucalyptus oil has antibacterial effects on pathogenic bacteria in the respiratory tract. Eucalyptol and other aromatic vapors (such as menthol) have been widely used in the symptomatic treatment of upper respiratory tract infections, and the efficacy of aromatic vapors as antitussives in chemically induced cough is proved. In a 2003 study eucalyptol was found to control airway mucus hypersecretion and asthma, after in a previous study the authors found eucalyptol to suppress arachidonic acid metabolism and cytokine production in human monocytes.
The antitussive effects of menthol, camphor and cineole in conscious guinea-pigs..
Anti-bacterial activity: Eucalyptus oil is also used in personal hygiene products for antimicrobial properties in dental care and soaps. It can also be applied to wounds to prevent infection.
Effect of Australian tea tree oil on the viability of the wall-less bacterium Mycoplasma pneumoniae.
Effect of eucalyptus essential oil on respiratory bacteria and viruses.
Anti-helmintic activity: E. globulus oil showed anthelmintic activity in a concentration-dependent manner.
Chromatographic evaluation and anthelmintic activity of Eucalyptus globulus oil.
Insecticidal activity:
Insecticidal Activity of the Essential Oils from Different Plants Against Three Stored-Product Insects
PHARMACOKINETICS
Eucalyptol, due to its apolar nature, is readily absorbed from the gastrointestinal tract, skin and respiratory tract. Human liver can’t detoxify Eucalyptol, but some Australian autochthon species can. Koala, Brushtail Possum and other animals have a liver able to metabolize this molecule.
1,8-Dihydroxy-10-carboxy-p-menthane,2-hydroxy-cineole and 3-hydroxy-cineole were found to be the main metabolites in rats after oral treatment with 800 mg of eucalyptol. Furthermore, different metabolites were obtained in the other experiment (rat and ‘brushtail possum’) such as p-cresol, 9-hydroxycineol, cineol-9-oic acid and benzoic acid. In rabbits given eucalyptol by gavage, the same hydroxylated metabolites, 2- and 3-hydroxycineole, were observed.
Constituents of aromatic plants: eucalyptol
MOLECULAR MECHANISM
Effects of the Nervous System:
Monoterpenoids such as Eucalyptol induce agonist-specific desensitization of transient receptor potential vanilloid-3 (TRPV3) ion channels. Transient receptor potential vanilloid-3 (TRPV3) is a thermo-sensitive ion channel expressed in skin keratinocytes and in a variety of neural cells. It is activated by warmth as well as monoterpenoids including camphor, menthol, dihydrocarveol and 1,8-cineol.
TRPV3 is described as a putative nociceptor and previous studies revealed sensitization of the channel during repeated short-term stimulation with different agonists. A prolonged exposure (5-15 minutes) of monoterpenoids results in agonist-specific desensitization of
TRPV3, explaining the transient coma, and symptoms which includes epigastric burning with nausea and usually vomiting, vertigo, ataxia, muscle weakness, stupor, pallor and sometimes cyanosis, respiratory stridor (edema) and myosis in eucalyptus intoxications. The receptor is expressed both in the
CNS and
PNS (where it explains the freezing sensation or the pain relieve).
Monoterpenoids induce agonist-specific desensitization of transient receptor potential vanilloid-3 (TRPV3) ion channels.
Monoterpenoid agonists of TRPV3.
Effects on the Immune System:
In Eucalyptus globulus, the major monoterpenoid component is eucalyptol (1,8-cineole), constituting the 60–90% that has been reported to inhibit the production and synthesis of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), leukotriene
B4, and thromboxane B2 in human blood monocytes.
Inhibition of cytokine production and arachidonic acid metabolism by eucalyptol (1.8-cineole) in human blood monocytes in vitro.
Monoterpenes are prescribed to treat chronic obstructive airway disorders mainly because of their familiar secretolytic properties, and, 1.8-cineole was shown to inhibit
LTB4 and
PGE2, both pathways of AA-metabolism.
Antiinflammatory effects of euclyptol (1.8-cineole) in bronchial asthma: inhibition of arachidonic acid metabolism in human blood monocytes ex vivo.
Eucalyptus oil also stimulates the phagocytic ability of human monocyte derived macrophages. Moreover, eucalyptol stimulation is able to provoke a more dramatic reorganization of microtubular filaments, strongly suggesting that tubulin plays an important role in the Eucalyptus Oil-induced macrophage activation. This suggests, almost preliminary, that Eucalyptus Oil might act by means of different mechanisms, possibly involving different phagocytic receptors. It is actually known that internalization by macrophages occurs by a restricted number of phagocytic receptors present on their surface.
Stimulatory effect of Eucalyptus essential oil on innate cell-mediated immune response
TOXICITY
If consumed internally at low dosage as a flavouring component or in pharmaceutical products at the recommended rate, cineole-based 'oil of eucalyptus' is safe for adults. However, systemic toxicity can result from ingestion or topical application at higher than recommended doses.
Reported Fatal Dose:
Eucalyptol Toxic Grade: 4. 4 (Very Toxic). Probable oral dose lethal for humans: 50-500 mg/Kg; between 1 teaspoon and an ounce for a 70 kg person.
[Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason. Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins, 1976., p. II-168]
Because of their high body surface area to mass ratio, children are more vulnerable to poisons absorbed transdermally. Severe poisoning has occurred in children after ingestion of 4 mL to 5 mL of eucalyptus oil
In higher than normal doses eucalyptol is hazardous via ingestion, skin contact or inhalation. It can have acute health effects on behavior, respiratory tract and nervous system. It is classified as a reproductive toxin for females and a suspect reproductive toxin for males.
Clinical cases:
- A healthy 4-year-old girl following dermal exposure to eucalyptus oil as directed for treatment of head lice (trattamento per pidocchi ndt). Initial symptoms were vomiting, lethargy, and ataxia followed by a grand mal seizure.
- A 6-year-old girl presented with slurred speech, ataxia and muscle weakness progressing to unconsciousness following the widespread application of a home remedy for urticaria containing eucalyptus oil.
- A case of 58 years old chemist, who due to intense delusions consumed 4-5 drops of concentrated EO in order to self-medication of ascariasis. Despite the low dose of ingested xenobiotic the course of poisoning was severe.
Reported symptoms of poisoning:
1 ml of Eucalyptol has caused a transient coma, symptoms included epigastric burning with nausea and usually vomiting, vertigo, ataxia, muscle weakness, stupor, pallor and sometimes cyanosis, respiratory stridor (edema) and myosis. Delirium and occasionally convulsions occur. Rarely symptoms may be delayed for 2 hours.
[Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason. Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins, 1976., p. II-168]
Vapor causes irritation of the human eye, perceptible at 175 ppm in air, and unpleasant at 720 to 1,100 ppm. Contact of the liquid with the eye causes immediate severe pain and blepharospasm. This may be followed by much conjunctival hyperemia and slight transient injury of the corneal epithelium.
[Grant, W.M. Toxicology of the Eye. 3rd ed. Springfield, IL: Charles C. Thomas Publisher, 1986., p. 961]
Turpentine and Eucalyptol are proved to induce hepatic microsomal enzymes in non-lethal exposures.
[Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason. Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins, 1976., p. II-168]
Occasional findings of dysuria, hematuria, albuminuria and glycosuria may reflect the ability of Monoterpenoids to irritate the urinary bladder and kidneys. Lesions appear to be transient and completely reversible: death is rarely if ever due to renal failure. (Monoterpenoids)
[Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason. Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins, 1976., p. II-168]
Symptomatology: occasionally painful urination, albuminuria, hematuria. The urine may have an odor resembling that of violets. The renal lesion is usually transient. (Monoterpenoids).
[Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason. Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins, 1976., p. II-168]
RESISTANCE
Cases of resistance to Eucalyptol are unknown.
DEPENDENCE AND WITHDRAW
Eucalyptol and other molecules contained in Eucalyptus oil are not addictive.
11/02/2013
