The Geography of Phytochemical Races

2.3 Europe 39
Fig. 2.20 Map of the area
around Vojvodina, Serbia
the bisbenzyldihydroisoquinolines thalmethine [79], O-methylthalmethine [80],
thalicberine [81], and O-methylthalicberine [82], and three monomeric compounds
thaliglucine [83], thaliprophine [84], and berberine [85] (see Fig. 2.21 for structures
79–87). A population collected in nearby Beocin (45°12′N, 19°41′E) afforded a
signifi cantly reduced yield of alkaloids, as well as a simpler array of compounds
consisting of the monomeric isoquinoline derivatives thalactamine [86], thalfl avine
[87], and berberine. It is also useful to note that plants from both of those areas were
shown to be hexaploid, refuting an earlier suggestion that alkaloid composition correlated
with ploidy number (Dutschewska and Kuzmanov, 1982; Kuzmanov and
Dutschewska, 1982).
As noted, the alkaloid yield from the Beocin plants was low, which the authors
suggested might be caused by the poor soil in which the plants were growing
(Popovic et al., 1992). One could ask whether the soil conditions to which they
refer might be infl uential in the overall alkaloid biosynthetic processes in this
species. It would be of interest to see experimental studies aimed at determining
the effect of soil components on these processes. In the present case, it may be a
lack of, or reduction in the activity of, the oxidase(s) necessary for the dimerization
process (required to form the bibenzyldihydroisoquinolines) to occur. It is
also possible that the lack of dimeric alkaloids may simply refl ect a concentration
effect caused by the edaphic conditions. These questions should be accessible
to experiment.