Terpenes mono- classes

From a chemical point of view, vegetable resins are a complex mixture of mono-, sesqui-, di- and triterpenes, which have, respectively, 10, 15, 20 and 30 carbon atoms per molecule. The mono- and sesquiterpenes are both present in most resins. The di- and triterpenes are rarely found together in the same resin, which means that terpenic resins can be divided into two main classes. Table 1.5 lists the botanical origin and the kind of terpenoid compounds of some natural resins. 

The official ACS report is limited to the naming of the simple acyclic, mono-cyclic, and bicyclic terpene hydrocarbons because official action has been taken only on the recommendations relating to these three classes of terpenes The term terpene hydrocarbons is intended to include not only the numerous C1QH16 hydrocarbons but also their hydrogenated derivatives and other hydrocarbons possessing similar fundamental structures they may be of natural or synthetic origin. 

Serum proteins see Plasma proteins. Sesquiterpenes aliphatic, mono-, di- or tricyclic terpenes, formed from three isoprene units (C15H24). About 100 structural types are known, and about 1,000 natural representatives, forming the largest class of terpenes. Most are found in the volatile oils of plants. Little is known of the physiological significance of S. some compounds have an ecological role (Table). Smne are isolated for use in perfumery. 

Perilla frutescens can be class ed in several chemotypes as well according to the main mono-terpene components perillaldehyde, elsholtzia ketone, or perilla ketones and on the other side phenylpropanoid types containing myristicin, dillapiole, or elemicin (Koezuka et al., 1986). A comprehensive presentation on the chemotypes and the inheritance of the mentioned compounds was given by this author in Hay and Waterman (1993). In the referred last two examples, not only the sensorial but also the toxicological properties of the essential oil compounds are decisive for the (further) commercial use of the respective species biodiversity. 

As widely acknowledged, the composition of essential oils is mainly represented by mono- and sesquiterpene hydrocarbons and their oxygenated (hydroxyl and carbonyl) derivatives, along with aliphatic aldehydes, alcohols, and esters. Terpenes can be considered as the most structurally varied class of plant natural products, derived from the repetitive fusion of branched five-carbon units (isoprene units) [7]. In this respect, analytical methods applied in the characterization of essential oils have to account for a great number of molecular species. Moreover, it is also of great importance to highlight that an essential oil chemical profile is closely related to the extraction procedure employed and, hence, the choice of an appropriate extraction method becomes crucial. On the basis... 

Mono-, sesqui-, di-, and sesterpenes contain the isoprene units linked in a head-to-tail fashion. The triterpenes and carotenoids (tetraterpenes) contain two C15 and C20 units, respectively, linked head to head. Many terpenes are hydrocarbons, but oxygen-containing compounds such as alcohols, aldehydes, or ketones are also found to fall in the class of terpenes. These derivatives are more frequently named as terpenoids. 

This a-domain is common to all class I terpene synthases and is the only domain in bacterial and fungal class I enzymes such as the pentalenene synthase from Streptomyces ey oliatus or the trichodiene synthase from Fusarium sporotri-chioides (Fig. 87.14a) [191,194]. Plant hemi-, mono-, and sesquiterpene synthases exhibit a second helical p-domain that resembles a barrel structure. An example of this class is given by the (+)-5-cadinene synthase from G. arboreum (Fig. 87.14b) [195]. In plant diterpene cyclases and in the exceptional case of the ( )-a-bisabolene synthase from A. grandis (Fig. 87.14c), a third helical y-domain with a barrel-like structure is present [197, 200, 202]. The p- and y-domains in the plant enzymes are nonfunctional but are required for correct enzyme folding. 

Caimabielsoin (CBE, 9)-type compounds formally derive from attachment of one of the two phenolic oxygen atoms to the endocyclic double bond of the CBD mono-terpene unit, thus generating a dihydrofuran-type ring [17]. Interestingly, compounds of the CBE class have also been detected during studies of the mammalian metabolism of CBD [18]. An aromatized analog of CBE, cannabifuran (CBF, 10) [19], is characterized by a dibenzofuran skeleton. 

Terpene Ksr- pen n [ISV terp- (fr. Gr Terpentin turpentine, fr. ML terbentina) + -ene] (1873) A class of unsaturated organic compounds having the empirical formula C10H16 occurring in most essential oils and oleoresinous plants. Structurally, the unimportant terpenes and their derivatives are classified as mono-cyclic (dipentene), bicyclic (pinene), and acyclic (myrcene). 

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