university of kwazulu-natal faculty of science and agriculture school ...

may be referred to as a norabietane due to the absence of the methyl group at C-4. Also
present in the structure is a double bond at ∆ 4 .
19
9
H
H
H
COOH
H
COOH
H
(19) abietic acid (20) levopimaric acid (21) ferruginol
HO
O
10
O
H
O
OH
7
H
O
H
α
9
β 8
(22) carnosol (23) callicarpone (24) royleanone
O
O
16
15
(25) tanshinone (26) dl-fichtelite
H
Figure 4: Representative structures of the different types of abietane diterpenoids
(Nakanishi et al., 1974)
The terms “nor”, “abeo” and “seco” are used widely in the abietanes. The use of “nor”
occurs when a methyl group is eliminated from the structure. The number preceding
“nor” refers to the carbon atom which has been eliminated. The prefix “abeo” is used
12
H
O
O
15
OH
20
O
10
7
OH
OH
O
6