The genus Cinnamomum

96 U.M. Senanayake and R.O.B. Wijesekera
PO CH 3
2
1
HO2C Mevalonic acid
PP
O
OPOP
OH
Geraniol
OH
OPP
the camphor isolated contained 0.0025% of the applied label. Unambiguous degradation
of the labelled camphor confirmed that labelled geraniol had been incorporated
specifically into camphor by this plant, indicating that geraniol had
isomerised to nerol.
Linalool, an acyclic monoterpene, is found in cinnamon leaf and stem bark oil to the
extent of 3%. It has been convincingly shown that linalool is formed from MVA in several
plant tissues. For example, Potty and Bruemmer (1970) and George-Nascimento and
Cori (1971) demonstrated that linalool, the major monoterpene in orange peel, is biosynthesised
from MVA, and Suga et al. (1971) obtained labelled linalool when (2–14C) MVA
was fed to Cinnamomum camphora. They suggested that geraniol had been transformed to
linalool, as linalool is a tertiary isomer of geraniol. Thus Fujita et al. (1975) obtained
an increased quantity of geraniol, nerol, limonene and terpineol when () linalool
(unlabelled) was administered to Fatsia japonica, Iris pseudacorus and Quercus phillyracoides.
Nerol
OH
Neryl – PP Nerol
α-Terpineol Limonene
+
OH
+
+
+
∆ 4 -Carene
Camphor Borneol α-Pinene Fenchol Thujone
Figure 3.5 Ionic mechanism in the biosynthesis of monoterpenes. Ruzica (1953) as modified by
Loomis (1967).
OH
OH
O
+
+