tetracyclic diterpenoid used for the growth of seedlings in the agricultural field
(Evans 2009). The chemical structures of sesquiterpenes are provided below in
Fig. 10.24.
10.5.5 Sesterterpenes
The meaning of the term “sester” is half to three, i.e., two and a half. Sesterterpenes
having five isoprene units containing 25 carbon atoms are rarely available. Geranyl
farnesol, a sesterterpenoid, extracted from seeds of the plant, Camellia sasanqua
a) Acyclic sesquiterpenes
C
H 3
CH 3
C
H 3
CH 3
C
H 2
CH 3
C
H 3
CH 3
C
H 3
CH 3
C
H 3
CH 3
O
H
alpha- Farnesene
beta- Farnesene
Nerodiol
b) Monocyclic sesquiterpenes
C
H 3
CH 3
C
H 3
CH 3
Zingiberene
CH 3
CH 3
OH
CH 3
C
H 3
CH 3
CH 3
CH 3
Elemol
Humulene
CH 3
O
CH 3
CH 3
Germacrone
c) Bicyclic sesquiterpenes
C
H 3
C
H 3
C
H 3
CH 3
OH
alpha- Cadinol
CH 2
OH
CH 3
C
H 3
beta- Eudesmol
CH 3
OH
CH 3
C
H 3
Guaicol
d)Tricyclic sesquiterpenes
CH 3
CH 3
CH 3
CH 3
OH
Cedrol
C
H 3
CH 3
CH 3
CH 2
Longifolene
Fig. 10.23 The structure of various classes of sesquiterpenes derived from plant sources
10 Secondary Metabolites from Plant Sources
359