SHIKIMIC ACID PATHWAY

THE SHIKIMIC ACID PATHWAYTHE 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.

Cleavage of the C3 side chain leads to many phenyl-C1 compounds.

C C C PhenylpropanoidsPhenylpropanoids

Phenyl-C3

CC C C

Phenyl-C1

glycolysis

PEP

GLUCOSE

Acetyl-CoA

pentose phosphatepathway

Erythrose-4-phosphate

Phosphoenol pyruvate

Shikimic Acid

ORIGINS OF THEORIGINS OF THESHIKIMIC ACIDSHIKIMIC ACIDPATHWAYPATHWAY

The pentose phosphatepathway is one that converts glucose intosugars of different sizes(different numbers of C)by acyl interchanges.Erythrose is a 4-carbonsugar.

A PRELIMINARY OVERVIEW

CHORISMIC ACID

SHIKIMIC ACID

PREPHENIC ACID

TYROSINE

PHENYLALANINE

CINNAMIC ACIDS

ALKALOIDS ALKALOIDS

PHENYL-C3COMPOUNDS

ShikimatePathways

PHENYL-C1COMPOUNDS

FLAVONOIDS

(+ acetogenin piece)

CINNAMYL COMPOUNDSCINNAMYL COMPOUNDS

CINNAMYL COMPOUNDSCINNAMYL COMPOUNDSCH2 C

O

COOH

CH2 C

OH

COOH

H

CH CH COOH

NADPH

- H2O

CH CH C S-Enz

O

CH CH C H

O

C

O

H

oxidativecleavage

Enz-SH

NADPH

cinnamic acid

cinnamaldehyde

benzaldehyde

The rings can have various numbers of hydroxylor methoxyl groups (hydroxylases and SAM).

CH2 CH2 COOH

hydrocinnamic acid

FADH2

COOH COOH

OH

COOH

OH

OH

COOH

OH

OMe

COOH

OH

OMeOH

p-coumaric acid caffeic acid ferulic acid

sinapic acid

COOH

OH

OMeMeO

CH2OH

OH

CH2OH

OH

OMe

CH2OH

OH

OMeMeO

p-coumaryl alcohol

coniferyl alcohol

sinapylalcohol

SOME NATURALLY-OCCURING CINNAMYL COMPOUNDSSOME NATURALLY-OCCURING CINNAMYL COMPOUNDS

CINNAMICACID

correspondingaldehydes arealso found -see next slide

sinapic acid

COOH

OH

OMeMeO

C

OH

OMeMeO

OSCoA C

OH

OMeMeO

OH

CH2

OH

OMeMeO

OH

HSCoA NADPH NADPH

sinapyl alcoholsinapyl aldehyde

TYPICAL REDUCTION SEQUENCESTYPICAL REDUCTION SEQUENCES

COOH

OMe OMe

CH2OH

OMe

OMe

anethole

estragole(methylchavicol)

CLEAVAGE TO CLEAVAGE TO PHENYL-C1 COMPOUNDSPHENYL-C1 COMPOUNDS

CLEAVAGE TO PHENYL-C1 COMPOUNDSCLEAVAGE TO PHENYL-C1 COMPOUNDS

COOH

OH

MeO

OH

MeO

C SCoAO

OH

MeO

C SCoAO

OHCCH2

OH

MeO

C SCoAO

O

C

OH

MeO

OSCoA

S

H

CoA:

C

OH

MeO

OOH

vanillic acid

CH2

COOH

OH

MeO

O

H

H

C

OH

MeO

OH

vanillin

reversealdol

reverseClaisen

H2O

H2O

H2O

ferulic acid

HSCoA NADP+

COUMARINSCOUMARINS

COOH COOH

OH OHCOOH

O OO OOH

umbelliferone

O OOH

OH

aesculetin

FORMATION OF COUMARINSFORMATION OF COUMARINS

isomerization

lactone(ester)

hydroxylase

coumarin

DICOUMAROL AND WARFARINDICOUMAROL AND WARFARIN

O O OO

OH OH

dicoumarol(sweet clover)

O

O

O

OH

Warfarin

O O

O

OO

OH

O O

OH

H C H

O

OH

C

O

SCoA

OH

C C

O

SCoA

O

..

:

- H2O

cinnamic acid

anti-coagulant

RODENTICIDE(rat poison)

causes internalbleeding in cows

FLAVONOIDSFLAVONOIDS

Plant Pigments

PLANT PIGMENTSPLANT PIGMENTS

Flavonoids and anthocyanins are conspicuous plant pigments in nature thatare 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 anthocyaninsare the source of red, violet and blue colors. These compounds occur mainly inhigher plants and are less common in the lower orders. You don’t find them inalgae, fungi or bacteria.

The flavonoids play a major role in attracting insects to feed and pollinate theseplants. 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 pathwayand the acetogenin pathway - they are of hybrid origin.

NARINGENINNARINGENIN

O

CoAS

OH

malonyl-CoA3x

OH

SCoA

OO

O

O

OH

OH O

OH

O

:

OH

OH O

OH

O

H

naringenin

A FLAVONE

internal Claisenand enolizations

A different starterthan acetyl-CoA.

acetogeninpathway

shikimic acidpathway

MIXED-ORIGINCOMPOUND

found in grapefruit

Michaeladdition

flavones are yellowor orange pigments

AnthocyaninFlower Pigments

Anthocyanin Leaf PigmentsAutumn Leaves

In Spring and Summerchlorophyll (green) masksthe anthocyanin colors.

OH

OH O

OH

O

R

naringenin (R=H)

OH

OH O

OH

O

OH

R

OH

OH O

OH

OH

OH

R

NADPH

[O]

OH

OH O

OH

OH

OH

R

OH

OH

OH O

OH

OH

R

+

- 2 H2O

O2

pelargonidin (R=H)cyanidin (R=OH)

ANTHOCYANIDINS AND ANTHOCYANINSANTHOCYANIDINS AND ANTHOCYANINS

plant flower andleaf pigments

ANTHOCYANIDINScyanidin is bluepelargonidin is pink

Anthocyanins arered, violet or bluepigments.

SUMMARYSUMMARY

REPEAT

CHORISMIC ACID

SHIKIMIC ACID

PREPHENIC ACID

TYROSINE

PHENYLALANINE

CINNAMIC ACIDS

ALKALOIDS ALKALOIDS

PHENYL-C3COMPOUNDS

ANTHRANILIC ACID

TRYPTOPHAN

ALKALOIDS

ShikimatePathways

PHENYL-C1COMPOUNDS

FLAVONOIDS

(+ acetogenin piece)

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