Descripción     ▲

Eucalyptus globulus is an evergreen tree, large size, belonging to the family Myrtaceae, native to Australia, but widely spread throughout the world, due to its easy adaptation to any habitat and its rapid growth. However, it requires temperatures not too extreme.

The plant is cultivated in the Iberian Peninsula since the late eighteenth century, when the import is started from its areas of origin.

Flowering occurs at the end of the hot season and first weeks of autumn, resulting in fruiting floral sets in capsules that contain several seeds.

The leaves are long, narrow and slightly curved, pointed and entire edge. They are harvested when mature.

Varieties and synonymy     ▲

There are more out of 700 species of eucalyptus, from which are known several varieties that share many of medicinal properties of Eucalyptus, as bicostata, globulus, and pseudoglobulus maidenii.

Folk names of eucalyptus globulus include Blue Gum Tree, Australian Gum Tree, Australian Fever Tree and Stringy Bark.

Composition     ▲

The leaves contain tannins, resins, etc., and, especially, essential oil, mostly cineole and eucalyptol(80%) in addition to other substances.

In 1995, the studies of Osawa et al. allowed first identification of eucalyptone, a new cariostatic compound[1].

In 1999, Shatalov and colleagues identified an heteroxylan polysaccharide composed by galactosyl, xylosyl and oxymethylglucoronosyl radicals[2]. Later, was isolated another heteroxylan acetylated compound[3].

Have also been isolated several compounds with inhibitory activity on peroxidation in liver microsomes of animal: pinoresinol, vomifoliol, trimethoxyphenol 1-O-beta-D-(6'-O-galloyl)glucopyranoside, methyl gallate, rhamnazin, rhamnetin, eriodictyol, quercetin, taxifolin, engelitin and catechin[4].

Eucaglobulin, a complex of gallotannin and monoterpene was identified in 2000 by a study together with hydrolyzable tannins known as tellimagrandin, eucalbanin, gallic acid and other substances[5].

Other components include various rhamnosides of ellagic acid [6] [7]. Fat cuticle of the fruits of Eucalyptus contain two main components, ursolic acid and tritriacontan-16,18-dione with other triterpene derivatives [8]. Other components of fruits include beta-sitosterol, betulinic acid, stigmasterol, 2a-hydroxybetulinic acid, euscaphic acid, macrocarpal A and B, oleanolic acid, 3,4,3'-O-trimethylellagic acid, 3-O-methylellagic acid 4'-O-(2"-O-acetyl )-alpha-L-rhamnopyranoside, camaldulenside (cypellocarpin C, 11), 3-O-methylellagic acid 4'-O-alpha-L-rhamnopyranoside, 3-O-methylellagic acid (13), ellagic acid (14), and gallic acid[9].

Recently, have been identified in the leaves of eucalyptus globulus two monoterpene glycosides with gallic acid conjugates (globulusin A and B) together with other four substances already known (cypellocarpin A, eucaglobulin, cuniloside and (1S, 2S, 4R)-trans-2-hydroxy-1,8-cineole beta-d-glucopyranoside. Globulusins possess powerful antioxidant and anti-inflammatory effects. This last was recently identified . Both compounds inhibit melanin synthesis[10].

Traditional uses     ▲

It is believed that leaves have therapeutic properties as asthmatic, decongestant, soothing, expectorant: and anticatarrhal. Also it is considered anti-inflammatory of respiratory and digestive tract, but is toxic at high doses and may produce digestive, respiratory and/or renal symptoms. Other commonly attributed properties include antiseptic, antibiotic, antidiabetic, antiviral, antispasmodic, antirheumatic, diaphoretic and antipyretic. Eucalyptus is a botanical resource very often used in the treatment of respiratory disease[11].

According to popular usage, the root has laxative properties and is used in some places for this purpose.

Mainly, the plant is used for treating respiratory catarrh episodes, although it is also used in chronic bronchitis, and headaches and neuralgias of diverse origin. In external application is used in rheumatism and as an antiseptic.

The Commission E indicates be contraindicated in digestive inflammatory, diseases of the biliary tract and liver. Should not be used during pregnancy and lactation.

How to apply:

Eucalyptus leaves may be administered by infusion (30 g/liter), for internal use as inhalations (50-60 g/liter) or externally as an antiseptic (The British Herbal Pharmacopoeia), diluting 20 ml of essential oil in 1 liter of water.

Clinical studies     ▲

In 2002 and 2003, studies conducted in Egypt by Morsy et al. with eucalyptus oil applied to patients with both types of infestations, by Demodex folliculorum and by Sarcoptes Scabie, have got encouraging results[12][13]. However, would be needed more and broader studies with methodological rigor to establish without any kind of doubt the clinical efficacy of eucalyptus oil in these parasitosis.

Experimental studies     ▲

Analgesic and anti-inflammatory effects

Essential oil from extract of eucalyptus has shown interesting analgesic and anti-inflammatory properties in experimental models in laboratory animals[14].

Oestrogenic activity:

An in vitro study concludes that the fluid from the eucalyptus pulp has an interesting estrogenic activity[15].

Antiparasitic effect:

One of the most recognized derivatives eucalyptus effects is the antiparasitic effect, against Pediculus capitis (lice) resistant to permethrin (essential oil), although no intervention studies in people[16]. Are also sensitive to the effects of the essential oil (or cineole) parasites as Lutzomyia longipalpis and Haemonchus contortus[17][18]. Aedes aegypti, the yellow fever mosquito, is susceptible to vapors of the essential oil of various species of Eucalyptus, including E. globulus. The cause of this toxicity is cineole, an active principle of eucalyptus species[19].

Eucalyptus extract has a remarkable antitrypanosome activity [20]. It has been demonstrated, using a mixture of gotu kola and eucalyptus, larvicide and adulticide effect against the malaria vector Anopheles stephensis with a minimal larval mortality of 80%[21].

Antibacterial effect:

The extract of different varieties of eucalyptus was shown to inhibit the growth of bacteria as Pseudomona aeruginosa[22]. It has not been possible to establish a correlation between this activity and the content of cineole and other components in eucalyptus. However, other authors believe that antibacterial activity is related to content of cineole[23].

The plant has shown a growth inhibitory action on some other bacteria in vitro (Haemophilus influenza, parainfluenza and Streptococcus pneumoniae) as well as against a range of common germs causing respiratory infections[24][25]. Regarding the methicillin-resistant Staphylococcus aureus, eucalyptus has a certain degree of inhibitory activity[26].

Globulol, a sesquiterpene derivative content in the fruits of eucalyptus has an inhibitory effect against the growth of common fungi (alternaria, fusarium, rhizoctonia, etc) as well as some bacteria such as Bacillus subtilis. Probably, this substance is the main antimicrobial agent from the fruits of Eucalyptus[27].

Eucalyptus medicinal applications could possibly be extended if was thoroughly investigated the inhibition of Epstein-Barr virus induced by euglobals[28]. A study has shown that several substances of this kind have presented an inhibitory effect in vitro on the virus that causes infectious mononucleosis.

Effects on bronchial secretions:

A chinese research group has demonstrated the anti-inflammatory effect of eucalyptus oil on chronic bronchitis induced by lipopolysaccharide and the inhibition of mucin hypersecretion[29].

Antiobesity effect:

Eucalyptus leaf extract locks the absorption of fructose in a dose-dependent manner and may even eliminate excessive body fat caused by ingestion of sucrose in laboratory animals[30].

Antioxidant effect:

Several studies conclude positively about the antioxidant effect of eucalyptus[31]. This plant would have an intermediate antioxidant potency.

Antidiabetic effect

Feeding with eucalyptus produced a reduction of blood glucose level on the experimental mice with streptozotocin diabetes and polydipsia, as well as a slower progression of weight loss. According to researchers, eucalyptus and other herbs delay the development of diabetes induced by streptozotocin[32]. Other authors identified a pancreatic and extrapancreatic effect of eucalyptus on diabetes[33]. Another researchers have come to the conclusion that eucalyptus extract reduces glucose levels in diabetic animal, but not restored glycogen to its previous level[34].

ADR, toxicology and interactions     ▲

Incubation of different substrates with a commercial mixture of CYP450 isozymes produced an inhibition of the activity of the isoenzymes in the presence of extracts of various herbs, including eucalyptus[35].

In general, the various preparations of eucalyptus are generally well tolerated , although there are no systematic studies about toxic effects of this plant.

From the limited information available, it follows that the manifestations of toxicity may be severe or even fatal, depending on the dose administered. Relatively small doses can cause gastrointestinal symptoms (nausea, vomiting, abdominal pain or diarrhea), while higher doses can lead neurological or psychological symptoms.

Eucalyptus can be neurotoxic by accelerating hepatic metabolism of certain anesthetics, analgesics and tranquilizers drugs. Its essential oil can not be applied directly on the face of young children or infants. It is considered that the ingestion of 30 ml of essential oil is lethal. Toxic symptoms are rapid and include abdominal pain, spontaneous vomiting, breathing problems, respiratory depression, tachycardia, convulsions and delirium. It is not recommended to take during pregnancy and lactation.

Conclusions     ▲

In spite of being a medicinal plant widely used, there is not available systematic studies that could give greater scientific arguments for its use. Unfortunately, the available information is insufficient to support the clinical use of this plant.

It must be remembered that eucalyptus can lock the main system of drug metabolism in the liver, which requires caution in patients undergoing drug treatment, since poisoning may occur even taking moderate doses of medicines.

References     ▲

1: Osawa K, Yasuda H, Morita H, Takeya K, Itokawa H. Eucalyptone from Eucalyptus globulus. Phytochemistry. 1995 Sep;40(1):183-4.
2: Shatalov AA, Evtuguin DV, Pascoal Neto C. (2-O-alpha-D-galactopyranosyl-4-O-methyl-alpha-D-glucurono)-D-xylan from Eucalyptus globulus Labill. Carbohydr Res. 1999 Jul 20;320(1-2):93-9.
3: Evtuguin DV, Tomás JL, Silva AM, Neto CP. Characterization of an acetylated heteroxylan from Eucalyptus globulus Labill. Carbohydr Res. 2003 Mar 28;338(7):597-604.
4: Yun BS, Lee IK, Kim JP, Chung SH, Shim GS, Yoo ID. Lipid peroxidation inhibitory activity of some constituents isolated from the stem bark of Eucalyptus globulus. Arch Pharm Res. 2000 Apr;23(2):147-50.
5: Hou AJ, Liu YZ, Yang H, Lin ZW, Sun HD. Hydrolyzable tannins and related polyphenols from Eucalyptus globulus. J Asian Nat Prod Res. 2000;2(3):205-12.
6: Kim JP, Lee IK, Yun BS, Chung SH, Shim GS, Koshino H, Yoo ID. Ellagic acid rhamnosides from the stem bark of Eucalyptus globulus. Phytochemistry. 2001 Jun;57(4):587-91.
7: Guo QM, Yang XW. A new ellagic acid derivative from the fruits of Eucalyptus globulus Labill. Pharmazie. 2005 Sep;60(9):708-10.
8: Pereira SI, Freire CS, Pascoal Neto C, Silvestre AJ, Silva AM. Chemical composition of the epicuticular wax from the fruits of Eucalyptus globulus. Phytochem Anal. 2005 Sep-Oct;16(5):364-9.
9: Yang XW, Guo QM. Studies on chemical constituents in fruits of Eucalyptus globulus. Zhongguo Zhong Yao Za Zhi. 2007 Mar;32(6):496-500.
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11: Andrade-Cetto A. Ethnobotanical study of the medicinal plants from Tlanchinol, Hidalgo, México. J Ethnopharmacol. 2009 Feb 25;122(1):163-71.
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17: Maciel MV, Morais SM, Bevilaqua CM, Silva RA, Barros RS, Sousa RN, Sousa LC, Brito ES, Souza-Neto MA. Chemical composition of Eucalyptus spp. essential oils and their insecticidal effects on Lutzomyia longipalpis. Vet Parasitol. 2010 Jan 20;167(1):1-7.
18: Macedo IT, Bevilaqua CM, de Oliveira LM, Camurça-Vasconcelos AL, Vieira Lda S, Oliveira FR, Queiroz-Junior EM, Portela BG, Barros RS, Chagas AC. Ovicidal and larvicidal activity in vitro of Eucalyptus globulus essential oils on Haemonchus contortus. Rev Bras Parasitol Vet. 2009 Jul-Sep;18(3):62-6. 19: Lucia A, Licastro S, Zerba E, Gonzalez Audino P, Masuh H. Sensitivity of Aedes aegypti adults (Diptera: Culicidae) to the vapors of Eucalyptus essential oils. Bioresour Technol. 2009 ec;100(23):6083-7.
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22: Cimanga K, Kambu K, Tona L, Apers S, De Bruyne T, Hermans N, Totté J, Pieters L, Vlietinck AJ. Correlation between chemical composition and antibacterial activity of essential oils of some aromatic medicinal plants growing in the Democratic Republic of Congo. J Ethnopharmacol. 2002 Feb;79(2):213-20.
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28: Takasaki M, Konoshima T, Fujitani K, Yoshida S, Nishimura H, Tokuda H, Nishino H, Iwashima A, Kozuka M. Inhibitors of skin-tumor promotion. VIII. Inhibitory effects of euglobals and their related compounds on Epstein-Barr virus activation. Chem Pharm Bull (Tokyo). 1990 Oct;38(10):2737-9.
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30: Sugimoto K, Suzuki J, Nakagawa K, Hayashi S, Enomoto T, Fujita T, Yamaji R, Inui H, Nakano Y. Eucalyptus leaf extract inhibits intestinal fructose absorption, and suppresses adiposity due to dietary sucrose in rats. Br J Nutr. 2005 Jun;93(6):957-63.
31: Dessí MA, Deiana M, Rosa A, Piredda M, Cottiglia F, Bonsignore L, Deidda D, Pompei R, Corongiu FP. Antioxidant activity of extracts from plants growing in Sardinia. Phytother Res. 2001 Sep;15(6):511-8.
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