BIOSYNTHESIS OF

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BIOSYNTHESIS OF INDOLE ALKALOIDS
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INDOLE ALKALOIDS
Biggest single class of alkaloids
- more than 1500
known.
Indole alkaloids come from trytophan which
originates from the shikimic acid pathway.
Many are of mixed-origin using geraniol, a
terpene as a precursor.
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TRYPTOPHAN SYNTHESIS
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ANTHRANILIC ACID
B-Enz
glutamic acid
NH3
H
H
anthranilic acid
chorismic acid
Tryptophan
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TRYPTOPHAN
anthranilic acid
imine
..

tautomers
phospho- ribosyl PP
enamine
H
TRYPTOPHAN
enol
tautomers
PLP
serine
H
- CO2 - H2O
reverse adol
keto
indole
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ALKALOIDS FROM TRYPTOPHAN
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PSILOCYBIN
SAM
PLP
tryptophan
tryptamine
O
O
ATP
PLP
5-hydroxytryptamine (5-HT, serotonin)
psilocybin
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Psilocybe spp
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b-CARBOLINE ALKALOIDS
tryptophan an aldehyde
tryptophan
aldehyde from an amino acid
a b-carboline
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b-CARBOLINE ALKALOIDS
tryptophan an a-ketoacid
tryptophan
Mannich Arom Subst
an a-ketoacid
Oxidative decarboxylation
harmine
harmaline
harman
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Ayahuasca
Banisteriopsis caapi
liana
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(No Transcript)
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Yopo
Anadenathra peregrina
Cohoba snuff
a legume
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Virola
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TERPENOID INDOLE ALKALOIDS
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There are a variety of alkaloids that have
tryptophan and geraniol as their precursors.
The geraniol precursor can yield a variety of
skeletal pieces as it rearranges readily via a
pathway containing two intermediates called
loganin and secologanin.
geraniol
loganin
secologanin
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SECOLOGANIN
Secologanin has so much functionality that it can
open bonds, rotate and make new bonds, easily
rearranging the carbon skeleton. Three
principal skeleton types are shown below. These
combine with tryptamine to form alkaloids (some
examples are given).
IRIDOIDS
IRIDANE SKELTON
Corynanthe type
akuammicine
secologanin
Iboga type
Aspidosperma type
tabersonine
catharanthine
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Iboga
Tabernanthe iboga
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Vinca
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SUMMARY
REPEAT
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( acetogenin)
SHIKIMIC ACID
Shikimate Pathways
FLAVANOIDS
CHORISMIC ACID
ANTHRANILIC ACID
PHENYL-C3 COMPOUNDS
PREPHENIC ACID
CINNAMIC ACIDS
TYROSINE
TRYPTOPHAN
PHENYLALANINE
PHENYL-C1 COMPOUNDS
ALKALOIDS
ALKALOIDS
ALKALOIDS
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ASSIGNMENTS
Read
Hesse
Alkaloids - Natures Cure or Curse
, Wiley-VCH (2000)
Chapter 7 Alkaloids
and Chemotaxonomy
, pp 237-256,
especially Section 7.2 which discusses the
formation of
secologanin and other iridoids from geraniol.
Schultes, Hofmann and Ratsch, Plants of the Gods,
Healing Arts Press (2001) All of these
are indole-based alkaloids (b-carbolines and
tryptamines) The Magic Drink of the Amazon, pp
124-139 (Ayahuasca) Beans of the Hekula Spirit,
pp116-119 (Yopo) Seeds of Civilization, pp
120-123 (Cebil) Semen of the Sun, pp 176-181
(Virola, Epena) Ibogamine is fromed from
an iridoid intermediate Guide to the Ancestors,
pp 112-115 (Iboga) Psilocybin
mushrooms Little Flowers of the Gods, pp
156-163 (Psilocybes)
(Yage)