**4. 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,

**Figure 4.** Structure of diterpenes.

**Figure 3.** Structures of sesquiterpenes.

**Names Plant source Activity Ref.**

A was the most active compound found in this study, with IC50 values of 0.10 μM against *Trypanosoma brucei rhodesiense* trypomastigotes and selectivity indices of [8]

20.5, respectively.

Santhemoidin A *Tarchonanthus camphoratus*

4 Terpenes and Terpenoids

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

and *Schkuhria pinnata*


**Table 3.** Source and biological activities of some diterpenes.

anticancer, and antifungal activities. Some of the diterpenes also have cardiovascular activity, such as grayanotoxin, forskolin, eleganolone, marrubenol, and 14-deoxyandrographolide. Kaurane and pimarane-type diterpenes are also biologically active metabolites isolated from the roots and leaves of different plants (**Table 3**).

**Figure 5.** Structures of sesterpenes.

Cybastacines A and B

Scalarane sesterterpenes

**Names Plant source Activity Ref.**

Mushroom species, *Pleurotus ostreatus* and *Scleroderma* 

*areolatum*

**Table 4.** Source and biological activities of some sesterpenes.

*Nostoc* sp. Cyanobacterium A and B showed moderate in vitro antibiotic

activities. Sesterterpenes are rare among microbial secondary metabolites, with only one report of a previous alkaloid—sesterterpene found in cyanobacteria. This discovery represents a significant addition to the novel chemical structures active

Introductory Chapter: Terpenes and Terpenoids http://dx.doi.org/10.5772/intechopen.79683 7

This compound exhibited moderate micromolar activity against *P. falciparum* 3D7 and *T. cruzi* Tulahuen C4 parasites. It showed <50% inhibition at 25 μM, when incubated with the tumoral liver cell

[15]

[16]

against resistant bacterial strains.

line, HepG2 (HB-8065) for 72 h.
