**3. Sesquiterpenes**

**Figure 2.** Structure of monoterpene.

ferent natural sources.

2 Terpenes and Terpenoids

**2. Monoterpenes**

9-OH-isoegomaketone [(2*E*)-1-(3-furanyl)-4-OH-4- Me-2-penten-1-one

class of secondary metabolites and basically consist of five carbon isoprene units which are assembled to each other (many isoprene units) by thousands of ways. Terpenes are simple hydrocarbons, while terpenoids are modified class of terpenes with different functional groups and oxidized methyl group moved or removed at various positions. Terpenoids are divided into monoterpenes, sesquiterpenes, diterpenes, sesterpenes, and triterpenes depending on its carbon units (**Figure 1**). Most of the terpenoids with the variation in their structures are biologically active and are used worldwide for the treatment of many diseases. Many terpenoids inhibited different human cancer cells and are used as anticancer drugs such as Taxol and its derivatives. Many flavorings and nice fragrances are consisting on terpenes because of its nice aroma. Terpenes and its derivatives are used as antimalarial drugs such as artemisinin and related compounds. Meanwhile, terpenoids play a diverse role in the field of foods, drugs, cosmetics, hormones, vitamins, and so on. This chapter provides introduction and information on the bioactive terpenes isolated currently from dif-

Monoterpenes consist of 10 carbon atoms with two isoprene units and molecular formula C10H16. These are naturally present in the essential and fixed oils of plants and related sources. Monoterpenes are structurally divided into the acyclic, monocyclic, and bicyclic type of

**Names Plant source Activity Ref.**

in the SC-CO2

It exhibited inhibitory activity on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW264.7 cells with an IC50 value of 14.4 μM. Compounds

the original plant were quantified by high-performance liquid chromatography with diode array detection.

extracts of the radiation mutant cultivar and

[2]

Leaves of *Perilla frutescens var. crispa*

**Table 1.** Source and biological activities of some monoterpenes.

Sesquiterpenes are the class of secondary metabolites consisting of three isoprene units (C15H24) and found in linear, cyclic, bicyclic, and tricyclic forms. Sesquiterpenes are also found in the form of lactone ring (**Table 2**). Many of the latex in latex-producing plants contain sesquiterpene, and these are potent antimicrobial and anti-insecticidal agent. Artemisinin, a sesquiterpene lactone, one of the most active compounds in *Artemisia annua* shoots and roots (**Figure 3**).



**4. Diterpenes**

**Figure 4.** Structure of diterpenes.

Diterpenoids belong to a versatile class of chemical constituents found in different natural sources having C20H32 molecular formula and four isoprene units (**Figure 4**). This class of compounds showed significant biological activities including anti-inflammatory, antimicrobial,

Introductory Chapter: Terpenes and Terpenoids http://dx.doi.org/10.5772/intechopen.79683 5

**Table 2.** Source and biological activities of some sesquiterpenes.

**Figure 3.** Structures of sesquiterpenes.
