Terpenes and Terpenoids

Tetraterpenes. Carotenoids make up the most important group of C q terpenes and terpenoids, although not all carotenoids contain 40 carbon atoms. They are widely distributed in plant, marine, and animal life. It has been estimated that nature produces about 100 million t/yr of carotenoids synthetic production amounts to several hundred tons per year (207,208). 

Terpenes (and terpenoids) are further classified according to the number of 5-carbon units they contain. Thus, monoterpenes are 10-carbon substances biosynthesized from two isoprene units, sesquiterpenes are 15-carbon molecules from three isoprene units, diterpenes are 20-carbon substances from four isoprene units, and so on. Monoterpenes and sesquiterpenes are found primarily in plants, but the higher terpenoids occur in both plants and animals, and many have important biological roles. The triterpenoid lanosterol, for example, is the precursor from which all steroid hormones are made. 

The analytical technique of choice for the identification of low molecular weight terpenes and terpenoids is GC/MS, assisted by off-line methylation or silylation reactions. However, comparable results in terms of sensitivity and response specificity... 

Fichan, I., Larroche, C., Gros, J.B. (1999) Water solubility, vapor pressure, and activity coefficients of terpenes and terpenoids. J. Chem. Eng. Data 44, 56-62. 

The bulk of plant-derived medicines can be categorized into a number of chemical families, including alkaloids, flavonoids, terpenes and terpenoids, steroids (e.g. cardiac glycosides), as well as coumarins, quinines, salicylates and xanthines. A list of some better-known plant-derived drugs is presented in Table 1.16. 

Terpene chemists use trivial names for most of the compounds because the systematic names are much more complex. Common or trivial names, CAS Registry Numbers, and properties of selected terpenes and terpenoids are listed in Tables 2 and 3. Compounds that exhibit chirality also have other Registry Numbers for specific optical isomers. For commercial products, a material safety data sheet (MSDS), which is required by OSHA, frequendy lists multiple names such as a product name, trivial name, IUPAC name and the TSCA name. The MSDS is a good source of information about physical properties, potential health hazards, and other useful information for the safe handling of the materials. When the product is a mixture, the components and their amounts are usually listed along with their Registry Numbers. 

TERPENES AND TERPENOIDS. The class of organic compounds known as terpenes is characterized by the presence of the repeating carbon skeleton of isoprene ... 

Robert T. l.aLonde, State University of New York. Syracuse. NY. Terpenes and Terpenoids... 

Indoor Chemistry Various terpenes and terpenoids are emitted from household products and building materials. Ozone that has entered from outdoors or has been generated indoors can react with these compounds, either in the gas phase or on the surface of materials. The resulting oxidation products will contribute to the production and growth of meaningful quantities of secondary organic aerosols (SOA). The formation and growth of SOA can be studied under controlled conditions in test chambers (see also Chapter 13). 

Fig. 4 Renewable platform chemicals used in olefin metathesis (a) plant oils and fatty acids, (b) terpenes and terpenoids, (c) phenylpropanoids, (d) natural rubber (cw-1,4-poly isoprene), (e) carbohydrates, (f) amino acids and peptides, and (g) furans...

Newman AA (1972) Chemistry of terpenes and terpenoids. Academic, London... 

Newman, A. A. Chemistry of Terpenes and Terpenoids, Academic Press New York, 1972. 

SUMMARY In essential oils, most constituents are terpenes and terpenoid molecules. The method of extraction can influence the terpene content. In citrus oils extracted by expression (squeezing or pressing the plant material), the terpenes present are similar to those found in the living plant tissue for example, orange, lemon, mandarin and grapefruit essential oils may be made up of up to 90% of the monoterpene limonene. When extraction is by steam distillation the action of the hot water and steam on thermolabile (heat-sensitive) molecules present in the plant is responsible for the formation of the bulk of the terpene content. Solvent extraction often produces absolutes that are very low in terpenes or do not contain them at all, when compared to a distillation of the same material, for example as found in lavender and rose products. 

The content of extractives and their composition vary greatly among different wood species and also within the different parts of the same tree (cf. Appendix). Wood extractives can be divided into three subgroups aliphatic compounds (mainly fats and waxes), terpenes and terpenoids, and phenolic compounds. Parenchyma resin is rich in aliphatic components and the oleoresin is mainly composed of terpenoids. Characteristic of the heartwood is the accumulation of phenolic compounds. 

The lipophilic fraction, extractable with nonpolar solvents (ethyl ether, dichloromethane, etc.) consists mainly of fats, waxes, terpenes and terpenoids, and higher aliphatic alcohols (cf. Sections 5.3.1 and 5.3.2). Terpenes, resin acids, and sterols are located in the resin canals present in the bark and also occur in the cork cells and in the pathological exudate (oleore-sin) of wounded bark. Triterpenoids are abundant in bark /3-sitosterol occurs in waxes, as an alcohol component, and the cork cells in the outer bark (periderm) of birch contain large amounts of betulinol (cf. Fig. 5-6). 

Oils Monoolein, cocoa butter, cardamom oil, tricaprylin, mineral oil, terpenes, and terpenoids... 

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