187
12
The coupling of an (R)- and (S)-N-methylcoclaurine leads to d-tubocurarine, the main
toxic ingredient of one kind of curare, used as arrow poison. Curare stands for a mix of
substances extracted from poisonous plants such as Strychnos toxifera (Loganiaceae, from
bark scrapings) and from several species of the Menispermaceae (such as Chondrodendron
tomentosum, Curarea sp., Caryomene sp. and Cissampelos sp.). Curare acts on the nicotinic
acetylcholine receptor (NAchR, see 7 Sect. 6.2).
After (S)-reticuline two main pathways can be distinguished, either via (S)-scoulerine
or via (R)-reticuline.
Tyrosine
Tyrosine
4-Hydroxyphenylacetaldehyde
Dopamine
Norcoclaurine
(S)-Coclaurine
Papaverine
(S)-Reticuline
(R)-Reticuline
(S)-Scoulerine
Thebaine
Morphine
(S)-N-Methylcoclaurine
Curare
Sanguinarine
Codein
Berberine
Noscapine
(S)-Laudanine
Laudanoside
HO
NH
OH
O
O
O
O
N
HO
NH 2
NH 2
COOH
COOH
HO
O
H
H
H
HO
N
O
O
H
H
H
HO
N
O
O
H
H
H
O
N
. Fig. 12.3 Schematic overview of the biosynthetic pathway of benzylisoquinoline alkaloids and representative members of various subfamilies
12.3 · Benzylisoquinoline Alkaloids (Derived from Tyrosine, e.g. Morphine and Curare)