The Geography of Phytochemical Races

4.3 North Pacifi c 191
4.3.1 Glehnia (Apiaceae)
Glehnia, a taxon restricted to eastern Asia and western North America, consists of
either two species, the Asian G. littoralis Fr. Schmidt ex Miq. and the North American
G. leiocarpa Mathias, or two subspecies of G. littoralis, subsp. littoralis and subsp.
leiocarpa. The Asian taxon occurs on sandy beaches of China and Japan, with the
North American taxon occupying the same type of habitat from northern California
to the northeastern coast of the Queen Charlotte Islands, British Columbia, and west
to Kodiak Island (Fig. 4.9). Both taxa are diploids with n = 11.
Itoh et al. (1997) showed that leaves, fruits, and rhizomes of G. littoralis accumulate
a rich array of furanocoumarins [332–339] as well as the polyacetylenic compound
panaxynol [340] (see Fig. 4.10 for structures). A second acetylenic compound,
falcarindiol [341], has also been reported from this species (Satoh et al., 1996).
Examination of plants collected throughout the range of the species in Japan revealed
two distinct chemical races, a northern form with imperatorin [335], isoimperatorin
[337], and 8-geranyloxypsoralen [338] as the major coumarins, and a low ratio of
panaxynol to total coumarin content (ratio less than 2), and a southern form characterized
by the presence of imperatorin as the major furanocoumarin and a much
higher ratio of panaxynol to total coumarin (ratio 1:10). Mizutani et al. (1993) concluded
that the level of genetic variation between the northern and southern forms
was quite low based upon restriction fragment-length polymorphism analyses.
The availability of North American specimens of Glehnia made it possible to
compare coumarin and acetylene profi les of this widely disjunct system (Hiraoka
et al., 2002). Analysis of plant material collected from four widely separated sites,
that is, northern California, central Oregon, northern Washington, and northeastern
Queen Charlotte Islands, British Columbia, revealed a profi le characterized by low
levels of furanocoumarins and a comparatively high level of panaxynol. The results
are similar to those that characterize the southern Japanese form. The North American
Fig. 4.9 Map of Glehnia occurrence, G. littoralis in Japan and east Asia, G. leiocarpa in western
coastal North America, and Kodiak Island