1. SHIKIMIC ACID PATHWAY

2. THE SHIKIMIC ACID PATHWAY
This pathway (unique to plants) leads to the formation of the
aromatic amino acids phenylalanine and tyrosine and to the
formation of many other phenyl-C3 compounds.
Phenylpropanoids
Phenyl-C3
Cleavage of the C3 side chain leads to many phenyl-C1 compounds.
Phenyl-C1

3. GLUCOSE ORIGINS OF THE SHIKIMIC ACID PATHWAY PEP Acetyl-CoA
pentose
phosphate
pathway
glycolysis
Erythrose-4-phosphate
PEP
Phosphoenol pyruvate
The pentose phosphate
pathway is one that
converts glucose into
sugars of different sizes
(different numbers of C)
by acyl interchanges.
Erythrose is a 4-carbon
sugar.
Acetyl-CoA
Shikimic Acid

4. FORMATION OF SHIKIMIC ACID
phosphoenol pyruvate B: H+
erythrose-4-phosphate H+ H+
NADPH
shikimic acid

5. FORMATION OF CHORISMIC ACID
hydrolysis
of PEP
ATP H+
shikimic acid
pyruvic acid
nucleophilic
addition to C=O :B
- H3PO4
- H2O
chorismic acid

6. PREPHENIC ACID phenylalanine tyrosine p-hydroxy- phenypyruvic
chorismic acid
Claisen Type
Rearrangement
prephenic acid
pseudoaxial conformation
Prephenic acid can be converted to phenylpyruvic acid
or to 4-hydroxyphenylpyruvic acid:
NADPH
NADP+
p-hydroxy-
phenylpyruvic
acid
phenypyruvic
acid
-H+
- CO2
-H-
-H+
- CO2
-OH
phenylalanine
tyrosine

7. CLAISEN REARRANGEMENT
A THERMAL REARRANGEMENT H+
heat
enolization
an allyl ether
an allyl phenol

8. PREPHENIC ACID TO PHENYLALANINE
:B-Enz
- CO2
phenylpyruvic acid
- H2O
prephenic acid H+
transamination
phenylalanine

9. PREPHENIC ACID TO TYROSINE
:B-Enz
- CO2
4-hydroxyphenyl-
pyruvic acid
NAD+
prephenic acid
transamination
hydride transfer
to NAD+
tyrosine

10. PHENYLALANINE AND TYROSINE COME FROM
A COMMON SOURCE AND ARE NOT CONVERTED
PREPHENIC ACID
phenylpyruvic acid
4-hydroxyphenylpyruvic acid X
tyrosine
phenylalanine
Although most plants could convert phenylalanine to tyrosine
using hydroxylases, this conversion is a minor pathway. Most
plants make enough tyrosine without converting phenylalanine.

11. A PRELIMINARY OVERVIEW

12. Shikimate Pathways SHIKIMIC ACID CHORISMIC ACID PREPHENIC ACID
(+ acetogenin piece)
PREPHENIC
ACID
PHENYL-C3
COMPOUNDS
FLAVONOIDS
CINNAMIC
ACIDS
TYROSINE
PHENYLALANINE
PHENYL-C1
COMPOUNDS
ALKALOIDS
ALKALOIDS

13. CINNAMYL COMPOUNDS

14. CINNAMYL COMPOUNDS The rings can have various numbers of hydroxyl
or methoxyl groups (hydroxylases and SAM).
NADPH
cinnamaldehyde
NADPH
- H2O
Enz-SH
oxidative
cleavage
FADH2
cinnamic acid
benzaldehyde
hydrocinnamic acid

15. SOME NATURALLY-OCCURING CINNAMYL COMPOUNDS
CINNAMIC
ACID
p-coumaric acid
caffeic acid
ferulic acid
corresponding
aldehydes are
also found -
see next slide
p-coumaryl
alcohol
coniferyl
alcohol
sinapyl
alcohol
sinapic acid

16. TYPICAL REDUCTION SEQUENCES
HSCoA
NADPH
NADPH
sinapic acid
sinapyl aldehyde
sinapyl alcohol
estragole
(methylchavicol)
anethole

17. CLEAVAGE TO
PHENYL-C1 COMPOUNDS

18. CLEAVAGE TO PHENYL-C1 COMPOUNDS
HSCoA
H2O
NADP+ :
ferulic acid
reverse
Claisen
H2O
H2O
reverse
aldol
vanillic acid
vanillin

19. COUMARINS

20. FORMATION OF COUMARINS
hydroxylase
isomerization
lactone
(ester)
umbelliferone
coumarin
aesculetin

21. DICOUMAROL AND WARFARIN: ..
- H2O
cinnamic acid
RODENTICIDE
(rat poison)
dicoumarol
causes internal
bleeding in cows
(sweet clover)
Warfarin
anti-coagulant

22. FLAVONOIDS
Plant Pigments

23. PLANT PIGMENTS
Flavonoids and anthocyanins are conspicuous plant pigments in nature that
are responsible for the beauty and splendor of flowers, fruits, fruit tree blossoms
and of the autumn leaves.
Flavones are responsible for the yellow and orange colors; and the anthocyanins
are the source of red, violet and blue colors. These compounds occur mainly in
higher plants and are less common in the lower orders. You don’t find them in
algae, fungi or bacteria.
The flavonoids play a major role in attracting insects to feed and pollinate these
plants. Some of them also have a bitter taste and repel harmful insects like
caterpillars.
Flavonoids are thought to be antioxidants, and play a major role in our diet,
preventing the ravages of aging caused by free-radicals.
These compound have their biosynthetic origin in both the skimic acid pathway
and the acetogenin pathway - they are of hybrid origin.

24. NARINGENIN found in grapefruit : MIXED-ORIGIN COMPOUND shikimic acid
pathway
NARINGENIN
A different starter
than acetyl-CoA.
found in grapefruit
malonyl-CoA 3x
acetogenin
pathway :
Michael
addition
internal Claisen
and enolizations
MIXED-ORIGIN
COMPOUND
A FLAVONE
flavones are yellow
or orange pigments
naringenin

25. Anthocyanin
Flower Pigments

26. Anthocyanin Leaf Pigments
Autumn Leaves
In Spring and Summer
chlorophyll (green) masks
the anthocyanin colors.

27. ANTHOCYANIDINS AND ANTHOCYANINS
NADPH
naringenin (R=H)
[O] +
Anthocyanins are
red, violet or blue
pigments.
- 2 H2O
pelargonidin (R=H)
cyanidin (R=OH)
plant flower and
leaf pigments
cyanidin is blue
pelargonidin is pink
ANTHOCYANIDINS

28. SUMMARY
REPEAT

29. Shikimate Pathways SHIKIMIC ACID FLAVONOIDS CHORISMIC ACID PREPHENIC
(+ acetogenin piece)
Shikimate
Pathways
SHIKIMIC ACID
FLAVONOIDS
CHORISMIC ACID
PREPHENIC
ACID
PHENYL-C3
COMPOUNDS
ANTHRANILIC
ACID
CINNAMIC
ACIDS
TYROSINE
TRYPTOPHAN
PHENYLALANINE
PHENYL-C1
COMPOUNDS
ALKALOIDS
ALKALOIDS
ALKALOIDS