the plants. They are divided into three groups (a) acyclic monoterpenes, e.g., citral,
geraniol, citronellal, Linalool (b) monocyclic monoterpenes, e.g., menthol, menthone, limonene, carvone, (c) bicyclic monoterpenes further grouped as (i) Chass I
or (6 + 3) membered ring systems: thujane type – a-thujene, sabinene and carane
type – carone, car-3-ene, car-2-ene (ii) Class II or (6 + 4) membered ring systems or
pinane type ring system: a-pinene, b-pinene, myrtenol, pinocarvone (iii) Class III or
(6 + 5) membered ring systems: camphor, camphene, borneol, isoborneol, fenchone (Fig. 10.22). Monoterpenes show a lot of pharmacological applications
(Table 10.5). The substances like camphor, as well as menthol are useful as
counterirritants, painkillers, and also act against skin infection like itching. They are
also used as anthelmintics. A group of monoterpene glycosides has reported
showing a vasodilation effect on coronary vessels, as well as the femoral vascular
bed (Kaur 2010, Lalonde 2005, Bergman 2019). The pharmaceutical uses of
monoterpenes are listed below in Table 10.5.
The chemical structures of different classes of monoterpenoids are provided
below in Fig. 10.22.
10.5.3 Sesquiterpenes
Sesquiterpenes composed of three isoprene units combined together in a head to tail
fashion and the molecular formula is C 15 H 24 . On the basis of biogenetic source,
about 200 various structural types of sesquiterpenes and many such compounds are
reported. Sesquiterpenes can be classified into four different classes in accordance
with their structure: (a) acyclic sesquiterpenes (e.g., a-farnesene, b-farnesene,
nerolidol), (b) monocyclic sesquiterpenes further subclassified as per basic skeleton
(i) Bisabolane type, e.g., zingiberene, b-bisabolene, (ii) Elemane type, e.g., abscisin
II, elemol (iii) Humulene type, e.g., humulene (iv) Germacrane type, e.g., germacrone aristolactone, (c) bicyclic sesquiterpenes are further subclassified into
(i) Cadinane type, e.g., a-cadinol, d-cadinolii) Eudesmane type, e.g., b- eudesmol,
santonin (iii) Perhydroazulene type, e.g., guaicol, aromadendrene (d) tricyclic
sesquiterpenes are further subclassified into (i) Cedrene type, e.g., cedrol, cedrene
(ii) Longifolene type, e.g., longifolene (Fig. 10.23) (Seigler 1995; Lalonde 2005;
Hikino 1985).
A group of sesquiterpene exhibit antimalarial, antibacterial, anthelmintic, antifungal, anti-inflammatory, antirheumatic, adaptogen, flavoring agent, counterirritant, and antiprotozoal activities (Table 10.6). The list of sesquiterpenes and their
uses are mentioned below in Table 10.6 (Kaur 2010; Lalonde 2005).
The chemical structure of sesquiterpenes is represented below in Fig. 10.23.
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C. C. Kandar
geraniol, citronellal, Linalool (b) monocyclic monoterpenes, e.g., menthol, menthone, limonene, carvone, (c) bicyclic monoterpenes further grouped as (i) Chass I
or (6 + 3) membered ring systems: thujane type – a-thujene, sabinene and carane
type – carone, car-3-ene, car-2-ene (ii) Class II or (6 + 4) membered ring systems or
pinane type ring system: a-pinene, b-pinene, myrtenol, pinocarvone (iii) Class III or
(6 + 5) membered ring systems: camphor, camphene, borneol, isoborneol, fenchone (Fig. 10.22). Monoterpenes show a lot of pharmacological applications
(Table 10.5). The substances like camphor, as well as menthol are useful as
counterirritants, painkillers, and also act against skin infection like itching. They are
also used as anthelmintics. A group of monoterpene glycosides has reported
showing a vasodilation effect on coronary vessels, as well as the femoral vascular
bed (Kaur 2010, Lalonde 2005, Bergman 2019). The pharmaceutical uses of
monoterpenes are listed below in Table 10.5.
The chemical structures of different classes of monoterpenoids are provided
below in Fig. 10.22.
10.5.3 Sesquiterpenes
Sesquiterpenes composed of three isoprene units combined together in a head to tail
fashion and the molecular formula is C 15 H 24 . On the basis of biogenetic source,
about 200 various structural types of sesquiterpenes and many such compounds are
reported. Sesquiterpenes can be classified into four different classes in accordance
with their structure: (a) acyclic sesquiterpenes (e.g., a-farnesene, b-farnesene,
nerolidol), (b) monocyclic sesquiterpenes further subclassified as per basic skeleton
(i) Bisabolane type, e.g., zingiberene, b-bisabolene, (ii) Elemane type, e.g., abscisin
II, elemol (iii) Humulene type, e.g., humulene (iv) Germacrane type, e.g., germacrone aristolactone, (c) bicyclic sesquiterpenes are further subclassified into
(i) Cadinane type, e.g., a-cadinol, d-cadinolii) Eudesmane type, e.g., b- eudesmol,
santonin (iii) Perhydroazulene type, e.g., guaicol, aromadendrene (d) tricyclic
sesquiterpenes are further subclassified into (i) Cedrene type, e.g., cedrol, cedrene
(ii) Longifolene type, e.g., longifolene (Fig. 10.23) (Seigler 1995; Lalonde 2005;
Hikino 1985).
A group of sesquiterpene exhibit antimalarial, antibacterial, anthelmintic, antifungal, anti-inflammatory, antirheumatic, adaptogen, flavoring agent, counterirritant, and antiprotozoal activities (Table 10.6). The list of sesquiterpenes and their
uses are mentioned below in Table 10.6 (Kaur 2010; Lalonde 2005).
The chemical structure of sesquiterpenes is represented below in Fig. 10.23.
356
C. C. Kandar