Sesquiterpenes eucalyptus

Baker and Smith have isolated from a number of eucalyptus oils, a sesquiterpene to which they have given the name aromadendrene. This compound was separated from the oil of eucalyptus nova-angelica in the dextrorotatory form, and from the oil of eucalyptus baUeyana in the laevorotatory form. The two specimens had the following characters —... 

Eudesmene is a sesquiterpene obtained by the dehydration of eudesmol, the sesquiterpene alcohol found by Baker and Smith in several species of eucalyptus oil. It has the following characters —... 

This sesquiterpene alcohol was discovered by Schimmel Co. in oil of Eucalyptus globulus. It is found in the last fractions of the distillate, separating out in crystalline condition. On recrystallisation from 70 per cent, alcohol, it was obtained in the form of brilliant, almost odourless needles, having the following characters —... 

Reports on volatile toxins originate primarily from studies on plants found in more arid regions of the world. Among the genera shown to release volatiles are Artemisia, Eucalyptus, and Salvia (4). When identified, the compounds were found to be mainly mono- and sesquiterpenes. Work of Muller and associates (13) has indicated that vapors of these compounds may be absorbed by surrounding plants, and that the chemicals can be absorbed from condensate in dew, or by plant roots after the compounds reach the soil. ... 

There are a number of allelochemicals among the mono-, sesqui-, and diterpenoids. In particular, plants in arid and semiarid regions produce diverse volatile terpenoids with allelopathic activity.5 Among the volatile monoterpenes, 1,8-cineole (4) and camphor (5) exhibit strong growth inhibitory effects on plants and are considered to be involved in plant competition. 1,4-Cineole (6), a minor isomer of 1,8-cineole, is a potent inhibitor of asparagine synthetase.6 -Menthane-3,8-diols (fir 7 and frw .r8), -menth-2-en-l-ols (cis 9 and trans 10), thymol (11), carvacrol (12), 1,8-cineole, cr-pinene (13), and /3-pinene (14) were isolated as allelopathic monoterpenes from Eucalyptus species.7 Eucalyptus trees also produce allelopathic sesquiterpenes including spathulenol (15), and a-, (3-, and 7-eudesmols (16-18).7... 

The only other class of sesquiterpenes isolated from Eremophila is the aromadendrane type which is represented by a single compound, (-r)-spathulenol (94), found in E.cuneifolia (67), E. paisley, E. racemosa and E. drummondii var brevis (14). First isolated from Eucalyptus spathulata (84), this compound has since been found to occur in a broad spectrum of plant genera (85). 

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. 

Among the oxygenated sesquiterpenes (Fig. 96.12), the oxidation product from p-caryophyllene, caryophyllene oxide, is widespread in plants. Also spathulenol is a widespread sesquiterpene alcohol. For example, it occurs in German chamomile and together with y-eudesmol as major oil component in Eucalyptus oleosa [36]. Daucol and carotol are aroma components found in the fruit oils from carrots (Daucus carotd) [27]. 

Eudesmol is a sesquiterpene found in eucalyptus. Propose a mechanism for its biosynthesis. 

Menthol (8-19) is a common cooling substance used in food products. The effect of coolness evoked through stimulation of the somatosensory system can be produced by several naturally occurring molecules, mainly derived from terpenes and sesquiterpenes. Such a molecule is (-)-isopulegol (8-319), occiuring, for example, in the essential oil of Australian lemon-scented gum (Eucalyptus citriodora, Myrtaceae) trees, which has 20% of the cooling... 

Eudesmol, which has been also named eucalyptus camphor, was first isolated from the oil of Eucalyptus piperita by H. G. Smith, who found it to be a crystalline body melting at 79 to 80, and having the formula Cxo xsO, and being, in all probability, an oxide. Semmler and Mayer, however, consider it to be a bii clic sesquiterpene alcohol, and this has since been confirmed by Semmler and Tobias, who give the following as its characters —... 

The same chemists have also made an examination of the sesquiterpene alcohol isolated from oil of Eucalyptus globulus by Schimmel Co., which they have named globulol. This body has the following characters —... 

H. G. Smith has also isolated a sesquiterpene, which is present in many eucalyptus oils in the portions boiling at a ve 255 , and which, in the oil of Encaiyptus hamastoma, represents as much as 50 per cent, of that fraction. It does not yield crystallised derivatives, hut, on the other hand, when dissolved in glacial acetic acid, it gives characteristic colour-reactions with acids and also with bromine. When submitted to the action of bromine vapour the oil acquires first a crimson-red colour, then violet, and finally indigo-blue. The sesquiterpene, prepared as pure as possible by fractional distillation, boils at atmospheric pressure at 260 to 265, and has at 19 the specific gravity 0 9 9. Smith proposes for the sesquiterpene the name aromadendrene . 

It contains eucalyptol, pinene, phellandrene, and a sesquiterpene. Oil of Eucalyptus Carnba. 

Eucalyptus oil contains usually 70-85% of eucalyptol (1,8-cineole) other constituents present are mostly monoterpene hydrocarbons (a-pinene, S-limonene, -cym-ene, P-pinene, a-phellandrene, camphene, y-terpinene, etc., with the first three in major amounts), with lesser amounts of sesquiterpenes (e.g., aromadendrene, allo-aromaden-drene, globulol, epiglobulol, ledol, and viridi-fiorol), aldehydes (e.g., myrtenal), ketones (e.g., carvone and pinocarvone), and others (jiANGSu). The eucalyptol content is 61.2% and 83.9% in Brazilian and Chinese eucalyptus, respectively. 

Despite their overall high abundance, the sesquiterpene hydrocarbons ( )-caryophyllene and )S-elemene were not detected by GCO and AEDA. This indicates that these compounds may play either no role or only a minor role in the overall aroma of O. sanctum. Results of AEDA (Table 1) indicate that eugenol cloves) is the predominant odorant in the essential oil, followed by jS-damascenone (floral, applesauce), 2-isopropyl-3-methoxypyr-azine (earthy, potato), and 1,8-cineol (minty, eucalyptus). The fact that eugenol and 1,8-cineol are key aroma components is not surprising and is supported by previous studies [1-9]. However, jS-damascenone and 2-isopropyl-3-methoxypyrazine had not been previously reported as components of O. sanctum. The AEDA procedure was conducted on the fresh herb to determine whether these latter components are indeed natural constituents of the herb or whether they are generated during the production of the... 

Aromadendranes are dimethylcyclopropane azulenes collectively named after the first isolated molecule of the family (+)-aromadendrane, found as a constituent of the essential oil of Eucalyptus trees. The occurrence of these sesquiterpenes in nature is high, with the higher plants essential oils to be their major sources. Some of the biological properties that have been reported for isolated aromadendranes include antifungal, antibacterial, antifeedant, and cytotoxic activities [75]. 

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