Narcissus and Daffodil

Alkaloids of Narcissus 171
Figure 6.12a Biosynthesis of galanthamine (69) proposed by Barton et al. (1963).
Figure 6.12b Biosynthesis of galanthamine (69) proposed by Eichhorn et al. (1998).
N-methylated to galanthamine (69) in the final step of biosynthesis (Eichhorn et al.,
1998) (Figure 6.12b). In contrast with the literature, N,O-dimethylnorbelladine
(90) was metabolised to a lesser extent in L. aestivum and incorporated into
galanthamine (69) as well as norgalanthamine (72) at about one-third the rate of
O-methylnorbelladine (80).
According to Eichhorn et al. (1998), narwedine (76) is not the direct precursor of
galanthamine (69), and could possibly exist in an equilibrium with galanthamine
(69), a reaction catalysed by a hypothetically reversible oxido-reductase.
SPECTROSCOPY
Only Proton Nuclear Magnetic Resonance ( 1 H-NMR), Carbon 13 Nuclear Magnetic
Resonance ( 13 C-NMR) and Mass Spectrometry (MS), the three most important
spectroscopic methods for the Amaryllidaceae alkaloids, will be treated here. A list
of the different narcissus alkaloids and their spectroscopic properties is given in
Table 6.3. The literature with the most recent spectroscopic data for these alkaloids
is given, even when they were isolated from species other than Narcissus.
Table 6.3 Narcissus alkaloids – spectroscopic data
Alkaloid* Formula MW Spectroscopic data References
18 assoanine C17H17NO2 267 UV, IR, MS,
1 13
H NMR, C NMR
19 oxoassoanine C17H15NO3 281 UV, IR, MS,
1 13
H NMR, C NMR
66 bicolorine C15H12NO2 238 IR, MS, 1 H NMR,
13
C NMR
57 bujeine C20H23NO6 373 IR, MS, 1 H NMR,
13
C NMR, CD
Llabrés et al., 1986b
Llabrés et al., 1986b
Viladomat et al., 1990
Labraña et al., 1999