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

HO
19
19
20
10
A H B
4 6
H
COOH
OH
O
20
13
12
11
C 14
1
10
A
5
4
9
B
8
7
OH
18
17
15
O
OH
11
C D 16
15
17
AcO
O
19
10
H
4 6
(11) Steviol (kaurane) (12) 2-acetoxy-1,15-beyeradiene-3,12-dione
(beyerane)
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16
3
11
20
10
5
18 19
H
18
9
20
H
Figure 1c: Tetracyclic (Class 5) diterpenes
13
11
O
15
OH
17
17
15
16
16
O
O
1
O
OH
20
(5) Horminone (abietane) (6) Totarol (totarane) (7) Phytocassane E (cassane)
3
1
19 18
OH
20
H
H
12
13
14
17
15
16
(8) 3β-dihydroxy-8(14),15-pimaradiene
(pimarane)
6
9
AcO
18
14
AcO OAc
H
17
11
A 15
1
20
B
19
8
C
4
H
H
16
OAc
3
18
1
20
19
1
H
3 5
12
11 13
15
10
H
8
12
H
14
3
14
HO O
19 18
(9) Taxusin (taxane) (10) 3β,12-dihydroxy-13-methyl-
5,8,11,13-podocarpatetraen-7-one
(podocarpane)
Figure 1b: Tricyclic (Class 4) diterpenes
20
OH
17
(13) Ent-16α-hydroxyatisane-3-one
(atisane)
8
12
8
OH
15
17
14
15
16