2.3 Natural Products Confused with Sesterterpenoids
Since all genuine sesterterpenoids should be derived from GFPP (8), the basic carbon
skeletons of many sesterterpenoids are composed of 25 carbon atoms. However, it
should be noted that not all compounds with basic carbon skeletons consisting of
25 carbon atoms are sesterterpenoids. Herein, we introduce examples of natural
products that could be confused with sesterterpenoids. When determining whether a
compound is a sesterterpenoid, it is essential to consider its biosynthetic origin.
OPP
OPP
OPP
OPP
OPP
OPP
hemiterpenoids
monoterpenoids
sesquiterpenoids
diterpenoids
sesterterpenoids
triterpenoids
tail-to-tail linkage
Fig. 12 Classification of
the terpenoids
8
OPP
isoprene unit
head
tail
17
a)
b)
head-to-tail linkage
tail-to-tail linkage
Fig. 13 (a) The “head” and
“tail” positions in the
isoprene unit. (b)
Compound 8 is formed only
by the “head-to-tail”
condensation of isoprene
units, while 17 is formed not
only by the “head-to-tail”
linkage but also by the “tailto-tail” linkage
Sesterterpenoids
9