Monoterpenes properties

Table 2. Properties of Selected Monoterpene Hydrocarbons and Ethers...

The sesquiterpenes found in essential oils have low volatilities compared with monoterpenes and so are isolated mainly by steam distillation or extraction, but some are also isolated by distillation or crystallization. Most of the sesquiterpene alcohols are heavy viscous Hquids and many crystallize when they are of high enough purity. Sesquiterpene alcohols are important in perfume bases for their odor value and their fixative properties as well. They are valuable as carriers of woody, balsamic, or heavy oriental perfume notes. 

Although cyclic terpene alcohols occur widely in nature, few have the physiological properties that make them important fragrance or flavor materials. Exceptions are a-terpineol and (—)-menthol, the latter because of its cooling/refreshing effect. Of the bicyclic monoterpene alcohols, bomeol deserves mention. 

A wide variety of EOs are known to possess antimicrobial properties and in many cases this activity is due to the presence of active constituents, mainly attributable to isoprenes such as monoterpenes, sesquiterpenes and related alcohols, other hydrocarbons and phenols [8, 9]. 

Monoterpenes hydrocarbons, such as sabinene [77, 78], terpinenes [12, 31, 32, 79, 80] and limonene [30, 73, 81-83], have also shown antimicrobial properties that appear to have strong to moderate antibacterial activity against Gram-... 

EOs and their monoterpenes alfected bone metabolism when added to the food of rats. It was demonstrated that these lipophilic compounds inhibited bone resorption [388], It was reported that (2 ,6iI)-8-hydroxy-2,6-dimethyl-2-octenoic acid, a novel monoterpene, from Cistanche salsa had antiosteoporotic properties [389]. 

The resin secreted by Cannabis indica and Cannabis sativa, varieties of hemp, is known variously as marijuana, hashish or bhang and is abused as a hallucinogenic drug. It appears however to have some beneficial properties and is currently under test as an antiemetic in cancer therapy. The secretion contains a number of interrelated oxygen heterocycles, some of which are shown in Scheme 281, which attempts to indicate their biosynthetic relationships (70MI22401). The cannabinoids are probably derived from a monoterpene unit based on p-menthane and 5-n-pentylresorcinol (olivetol), acting the part of a polyketide. 2,2-Dimethylchromene biosynthesis also requires the intervention of an isoprene fragment. 

The polyhalogenated monoterpenes 57-59 from the Spanish sea hare Aplysia punctata show identical cytotoxic properties against P-388 mice lymphoma and HT-29 human colon carcinoma (ED50 2.5 pg/ml), A-549 human lung carcinoma and MEL-28 human melanoma cell lines (ED50 1.5 pg/ml) [57]. 

It is difficult to select rationally a penetration enhancer for a given permeant. Accelerant potencies appear to be drug specific, or at best may be predictive for a series of permeants with similar physicochemical properties (such as similar partition coefficients, molecular weights, and solubilities). Some broad trends are apparent, such as the use of hydrocarbon monoterpenes for lipophilic permeants, but the level of enhancement expected for these agents is unpredictable. 

The genus Artemisia contains more than 200 species that have been reported from many parts of the world and has been selected for remedies by cultures throughout the world because of its medicinal properties. The reported active constituents of the genus include all types of the common natural products of the Asteraceae SQLs, polyacetylenes, flavonoids, essential oils (monoterpenes),... 

Monoterpenes Some antioxidant properties aid in activity of Basil, citrus fruits, broccoli, orange and... 

Thymol (isopropyl-m-cresol) is a volatile, phenolic monoterpene produced by several plants including thyme (Thymus vulgaris L.) (Baerheim Svendsen and Scheffer, 1985). Thymol has well-known antiseptic, antifungal, and anthelminthic properties (Wilson et al., 1977) and is also used for food and fragrance applications (Bauer et al., 1990). 

Ginger owes its characteristic organoleptic properties to two classes of constituents the odour and the flavour of ginger are determined by the constituents of its steam-volatile oil, while the pungency is determined by non-steam-volatile components, known as the gingerols. The steam-volatile oil comprises mainly of sesquiterpene hydrocarbons, monoterpene... 

The aroma and flavour of ginger are determined by the composition of its steam-volatile oil, which is comprised mainly of sesquiterpene hydrocarbons, monoterpene hydrocarbons and oxygenated monoter-penes. The monoterpene constituents are believed to be the most important contributors to the aroma of ginger and they tend to be relatively more abundant in the natural oil of the fresh ( green ) rhizome than in the essential oil distilled from dried ginger. Oxygenated sesquiterpenes are relatively minor constituents of the volatile oil but appear to be significant contributors to its flavour properties. 

Boelens et al. (1990) compared the quality of essential oils from various plant materials for hydrodiffusion and hydrodistillation. Hydrodiffusion oils contained higher levels of oxygenated monoterpenes and benze-noids and possessed preferred olfactive and organoleptic properties. 

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