molecule, as glycosides form or in other combinations (Seigler 1995). The
oleo-gum-resin of Boswellia carterii contains two types of triterpenoids namely,
one is b-Boswellic acids (ursane-type triterpene) and anther one is a-boswellic
acids (oleanane-type triterpene). These compounds exhibit anti-inflammatory, as
well as antirheumatic properties. Limonoids are tetracyclic triterpenoids but triterpenoid saponins are pentacyclic triterpenoids. An example of medicinally important
triterpenoid is cardiac glycosides or steroid glycosides used as cardiotonic by
increasing the force of systolic contraction in congestive cardiac failure (CCF).
Another important class of compounds, quassinoids is isolated from Quassia
amara. Quassinoids are compounds having less than 30 carbons and are
a) Acyclic diterpenes
C
H 3
CH 2 OH
CH 3
CH 3
CH 3
CH 3
Phytol
b)Monocyclic diterpenes
CH 2 OH
CH 3
CH 3
CH 3
CH 3
CH 3
Vitamin A 1 (Retinol)
c)Tricyclic diterpenes
CH 3
C
H 3
COOH
CH 3
CH 3
Abietic acid
d)Tetracyclic diterpenes
C
H 3
CH 3
OC
O
COOH
CH 2
OH
Gibberellic acid ( GA 3 )
Fig. 10.24 The structures of lignan derivatives derived from plant sources
10 Secondary Metabolites from Plant Sources
361