O
H
O
H
OH
O
OH
O
H
O
O
O
H
O
O
O
OH
O
OH
O
H
O
OH
OH
OH
OH
O
O
OH
OH
Shikimic acid
+
α-Ketoglutaric acid
o-Succinylbenzoic acid
Mevalonic acid
Alizarin
Shikimic acid pathway
6.4.5 Isoprenoid glycosides
The aglycone of this type of glycoside is biosynthetically derived from
isoprene units. There are two major classes of isoprenoid glycosides:
saponins and cardiac glycosides.
Saponins
Saponin glycosides possess ‘soaplike’ behaviour in water, i.e. they produce
foam. On hydrolysis, an aglycone is produced, which is called sapogenin.
There are two types of sapogenin: steroidal and triterpenoidal. Usually, the
sugar is attached at C-3 in saponins, because in most sapogenins there is a
hydroxyl group at C-3.
3
A steroid nucleus
A triterpenoid nucleus
3
The two major types of steroidal sapogenin are diosgenin and hecogenin.
Steroidal saponins are used in the commercial production of sex
hormones for clinical use. For example, progesterone is derived from
diosgenin.
6.4 GLYCOSIDES
325
H
O
H
OH
O
OH
O
H
O
O
O
H
O
O
O
OH
O
OH
O
H
O
OH
OH
OH
OH
O
O
OH
OH
Shikimic acid
+
α-Ketoglutaric acid
o-Succinylbenzoic acid
Mevalonic acid
Alizarin
Shikimic acid pathway
6.4.5 Isoprenoid glycosides
The aglycone of this type of glycoside is biosynthetically derived from
isoprene units. There are two major classes of isoprenoid glycosides:
saponins and cardiac glycosides.
Saponins
Saponin glycosides possess ‘soaplike’ behaviour in water, i.e. they produce
foam. On hydrolysis, an aglycone is produced, which is called sapogenin.
There are two types of sapogenin: steroidal and triterpenoidal. Usually, the
sugar is attached at C-3 in saponins, because in most sapogenins there is a
hydroxyl group at C-3.
3
A steroid nucleus
A triterpenoid nucleus
3
The two major types of steroidal sapogenin are diosgenin and hecogenin.
Steroidal saponins are used in the commercial production of sex
hormones for clinical use. For example, progesterone is derived from
diosgenin.
6.4 GLYCOSIDES
325