source of eugenol and star anise (Illicium verum, family Illiaceae) produces
high amounts of anethole. The biosynthesis of phenylpropanoids follows the
shikimic acid pathway, and the immediate precursor of cinnamic acid is
phenylalanine. Other phenylpropanoids, and a number of other phenolics,
e.g. coumarins, flavonoids and lignans, originate from cinnamic acid.
O
O
OH
O
H
OH
O
O
OH
O
O
O
OH
O
O
O
O
O
H
N
H 2
O
O
H
O
O
Shikimate
Phosphoenol pyruvate
Chorismate
Prephenate
-
Phenylalanine
Cinnamate
-
Other phenylpropanoids
e.g. Coumaric acid
Deamination
Phenylalanine
ammonia lyase
6.7.2 Lignans
The lignans are a large group of plant phenolics, biosynthesized from the
union of two phenylpropane molecules; e.g., both matairesinol (Centaurea
species, family Asteraceae) and podophyllotoxin (Podophyllum peltatum,
family Berberidaceae) are formed from the phenylpropane coniferyl
alcohol. Lignans are essentially cinnamoyl alcohol dimers, though further
cyclization and other structural modifications result in various structural
types, e.g. dibenzylbutyrolactone and epoxy lignan.
O
O
O
H
OH
OMe
MeO
H
H
O
O
OMe
O
O
OH
MeO
OMe
OH
OH
OMe
O
OH
MeO
O
OH
OMe
O
O
OMe
H
H
O
O
MeO
OMe
Matairesinol
A dimeric phenylpropanoid
Podophyllotoxin
A well known cytotoxic compound
2 x
Coniferyl alcohol
+
Yatein
A dimeric phenylpropanoid
6.7 PHENOLICS
361
high amounts of anethole. The biosynthesis of phenylpropanoids follows the
shikimic acid pathway, and the immediate precursor of cinnamic acid is
phenylalanine. Other phenylpropanoids, and a number of other phenolics,
e.g. coumarins, flavonoids and lignans, originate from cinnamic acid.
O
O
OH
O
H
OH
O
O
OH
O
O
O
OH
O
O
O
O
O
H
N
H 2
O
O
H
O
O
Shikimate
Phosphoenol pyruvate
Chorismate
Prephenate
-
Phenylalanine
Cinnamate
-
Other phenylpropanoids
e.g. Coumaric acid
Deamination
Phenylalanine
ammonia lyase
6.7.2 Lignans
The lignans are a large group of plant phenolics, biosynthesized from the
union of two phenylpropane molecules; e.g., both matairesinol (Centaurea
species, family Asteraceae) and podophyllotoxin (Podophyllum peltatum,
family Berberidaceae) are formed from the phenylpropane coniferyl
alcohol. Lignans are essentially cinnamoyl alcohol dimers, though further
cyclization and other structural modifications result in various structural
types, e.g. dibenzylbutyrolactone and epoxy lignan.
O
O
O
H
OH
OMe
MeO
H
H
O
O
OMe
O
O
OH
MeO
OMe
OH
OH
OMe
O
OH
MeO
O
OH
OMe
O
O
OMe
H
H
O
O
MeO
OMe
Matairesinol
A dimeric phenylpropanoid
Podophyllotoxin
A well known cytotoxic compound
2 x
Coniferyl alcohol
+
Yatein
A dimeric phenylpropanoid
6.7 PHENOLICS
361