Eucalyptus genera

Piperitone, with its fresh minty camphor4ike odor, is present in various leaf essential oils. Among Mentha and Eucalyptus genera, there are piperi tone-rich species which are considered common sources of this natural monoterpene ketone. The (45) (-f)- enantiomer was reported to be... 

Table 8. A Part of the Euglobals Classification ol Eucalyptus Genus and Existence of...

Eucalyptus oils are produced from plants belonging to the genus Eucalyptus (Myrtaceae), which includes ca. 500 species in Australia, the country of origin, alone. Correct botanical classification was possible only by determining the chemical composition of the essential oils obtained from the leaves. At present, few of these oils are commercially important. 

The Myrtaceae is commonly subdivided into two subfamilies, the Leptospermoideae, which is distributed mostly in Asia and Africa, and the Myrtoideae, found in tropical America, Asia, Australia, and the Pacific. The myrtle family is best known from Australia. Many species in the genera Eucalyptus, Calliostemon, and Verticordia, among others, are found in Australia. However, many genera such as Psidium are present in the Americas, and Myrtus of the Mediterranean and Northern Africa. The genus Eucalyptus is probably the best known representative of the Myrtaceae. 

The flowers of Leptospermum resemble flattened roses, and the small dark green leaves resemble those of the herb rosemary. Before tea was available in Australia, the leaves of Leptospermum were used as a substitute for tea, which is made from the dried leaves of a species of Camillia. From this early use by European settlers, the genus Leptospermum derives the common name tea-trees. Young branches and dried seed pods of Eucalyptus are popular in floral arrangements. The young branches have the attractive round leaves tightly appressed to the stem and are characteristic of juvenile material from species of the Myrtaceae. The leaves are mottled with wax. 

It was mentioned earlier that charcoal makers are well aware that woods from different tree species yield charcoals of differing quality. These differences can be linked to differences in wood anatomy and composition. There are well known and well-characterised anatomical and chemical differences between softwoods and hardwoods, for example [13], and softwood charcoal is widely regarded as inferior to that from hardwoods. Significant differences can also exist between the charcoals and charcoal yields from superficially similar species of the same genus. This has been shown in the case of Eucalyptus species [14][15]. There can even be differences in charcoals made from trees of the same species when these come from regions with dissimilar climates or soil types. 

Haslett AN (1988) A guide to handling and grade-sawing plantation-grown eucalypts. New Zealand Ministry of Forests, Forest Research Institute Bulletin 142 Hathway DE (1962) The use of hydroxystilbene compounds as taxomic tracers in the genus Eucalyptus. Biochemical Journal, 83 80-4... 

In the course of the last century and a half probably at least 6000, and possibly more than 10,000 essential oils have been analyzed or reported in one way or another. Of the single plant family Pinaceae for example, more than 200 oils have been examined of the single genus Eucalyptus an equal number of the single species Citrus at least 21—14 of these from the single subspecies amara. 

EUCALYPTUS OIL Eucalypti aetheroleum is obtained by steam distillation of fresh leaves (in practice whole twigs) of Eucalyptus /lobulus Labill. and other Eucalyptus species, such as E. fructicetorum F. von Muller (=E. polybractea RF. Baker), family Myrtaceae. The genus Eucalyptus belongs to the Australian flora, but now has a global distribution by... 

Isopinocamphone is the main constituent of oil of hyssop, Hyssopus officinalis (Lamiaceae), imparting the typical mucolytic properties of ketones, while muscle relaxant activity has been demonstrated in vivo (Lu et al. 2002). Piperitone is the main constituent of the leaf oils of the so-called peppermint group of the genus Eucalyptus. An example is the broad-leaf peppermint. Eucalyptus dives, an excellent, non-irritant mucolytic agent for sinus congestion and bronchitis (Schnaubelt 1995). 

Doran, J.C., 2002. Genetic improvement of eucalyptus. In Eucalyptus—The Genus Eucalyptus. Medicinal and Aromatic Plants—Industrial Profiles, J.J.W. Coppen (ed.). Vol. 22. pp. 75-101. London. U.K. ... 

As mono- and sesquiterpenes contain 10 or 15 carlxMi atoms arranged in various branched and often cyclic structures, the chemical systematic nomenclature according to lUPAC [23] results in complex names that are used in handbooks and databases. For a practical use for frequently occurring or used compounds, common names have been applied, mostly derived from prominent plant sources, as pinene from Pinus, the genus of the fir trees or eucal3q)tol from the eucalyptus oils. 

Conde, E., Cadahia, E., and Garcia-Vallejo, M. C. (1992). Optimization of TLC for research on the flavonoids in wood and bark of species of the genus Eucalyptus L Her-tier. Chromatographia 33 418-426. 

Hathway D E 1962 The use of hydroxystilbene compounds as taxonomic tracers in the genus Eucalyptus. Biochem J 83 80-84... 

The biological activity of essential oils is strictly connected with their chemical composition. Since essential oils are natural products, their composition cannot be precisely quantified. Correct botanical description of the plant material is out of discussion. The genus Mentha L. comprises about 25 species and even 900 taxons, there are hundreds of eucalyptus species and varieties. Different thyme and oregano species or even genera are accepted universally as thyme or oregano, respectively. That is the main reason that oils marketed at the same name showed great variability between the antimicrobial action, e.g. eucalyptus or chamomile (Lis-Balchin et al. 1998). 

An example of terpenic 1,2-epoxides is -caryophyllene oxide, also known as (-)-epoxycaryophyllene (8-31), which occurs in many essential oils. An example of terpenic 1,4-epoxides is the so-called (-l-)-dill ether, (3J ,4S,8S)-3,9-epoxy-p-menth-l-ene (8-31), which is a typical component of the essential oil of caraway (30%) and dill. An example of unsaturated 1,4-epoxides is (-l-)-menthofuran (8-31), the metabolite of ketone (-l-)-pulegone. Both compounds are components of peppermint oil (see Table 8.32, later) and are hepatotoxic. Monoterpenoid compound (- -)-l,8-cineole (also known as limonene oxide, eucalyptol or 1,8-epoxy-p-menthane 8-31) is an example of more complex structures. It is present in essential oils of many types of spices, and higher quantities are found in the essential oil of trees of the genus Eucalyptus (Myrtaceae). Trivial and systematic names of selected ethers are given in Table 8.8. 

As, however, the name has become so interwoven with the eucalyptus literature of Victoria and New South Wales in connection with the economics of the tree found there, it is now almost next to impossible to supersede the name of the tree of the Eastern States, or at least without adding to the already long nomenclature of the genus. 

Perhaps the greatest contribution by an Australian native plant has been Cotymbia citriodora. It is a tall tree from temperate and tropical northeastern Australia. This tree species has previously been known as Eucalyptus citriodora but following a taxonomic revision, it has been reclassified into the genus Corymbia. 

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