*2.1.1 Carbures*

*Essential Oils - Bioactive Compounds, New Perspectives and Applications*

molecular (see **Figure 1**).

**2.1 Terpenes**

methyl isocyanate (20.0%), thymol (15.5%) [41].

chemical group constituent of essential oils.

and camphor (24%) of the *Artemisia herba-alba* essential oil, 1,8-cineole (50%) of the *Cinnamomum camphora* essential oil, α-phellandrene (36%) and limonene (31%) of leaf (of what)? and carvone (58%) and limonene (37%) of seed *Anethum graveolens* essential oil, menthol (59%) and menthone (19%) of *Mentha piperita* essential oil. Generally, these major components determine the biological properties of the essential oils. The components include two groups of distinct biosynthetical origin [36–39]. The main group is composed of terpenes and terpenoids and the other of aromatic and aliphatic constituents, all characterized by low

The essential oil of juniper berry (*Juniperus drupacea* L.) was analyzed by chromatographic analysis and it was found that α-pinene (44.2%), thymol methyl ether (22.2%) and camphor (10.2%) present in higher concentration [40]. The major volatile compounds found in caper (*Capparis ovata* desf. Var*. caescens*) bud oil were benzyl alcohol (20.4%), furfural (7.4%), ethanol methyl pentyl acetal (5.9%), thymol (5.1%) as well as the major volatile compound found in capers leaves were

The following paragraphs will descript some features that characterize each

Terpenes form structurally and functionally different classes. They are made from combinations of several 5-carbon-base (C5) units called isoprene. The biosynthesis of the terpenes consists of synthesis of the isopentenyl diphosphate (IPP) precursor, repetitive addition of IPPs to form the prenyldiphosphate precursor of the various classes of terpenes, modification of the allylic prenyldiphosphate by terpene specific synthetases to form the terpene skeleton and finally, secondary enzymatic modification (redox reaction) of the skeleton to attribute functional properties to the different terpenes. The main terpenes are the monoterpenes (C10) and sesquiterpenes (C15), but hemiterpenes (C5), diterpenes (C20), triterpenes

*The structure of the chemicals discussed in this chapter with respect to their biological activity in alphabetical* 

**156**

*order.*

**Figure 1.**

