The Geography of Phytochemical Races

20 2 Examples Within Continents
Table 2.2 Occurrence of sesquiterpenes and aromatic esters in the liverwort, Isotachis lyallii, in
New Zealand (from Asakawa et al., 1997)
Compoundsa South Island North Island
Bicyclogermacrene [44] ++ b ++
Anastreptene [45] +++ +++
Aromadendrene [46] + −
Spathulenol [47] + ++
Benzyl benzoate [48] − ++
Phenylethyl cis-cinnamate ++ −
Phenylethyl trans-cinnamate
a Structures shown in Fig. 2.9.
b Relative concentrations.
++++ −
bicyclogermacrene [44] (see Fig. 2.9 for structures 44–49), anastreptene [45],
aromadendrene [46], and spathulenol [47], while the ester array consisted of benzyl
benzoate [48] and both isomers of β-phenylethyl cinnamate [49]. The occurrence of
these compounds from the North Island and South Island are given in Table 2.2. The
authors suggested that spathulenol might be an artifact formed from bicyclogermacrene
by autooxidation, as shown by Toyota et al. (1996). Nonetheless, spathulenol
might also be derived from aromadendrene by enzymatic oxidation. If that
were the case, the absence of aromadendrene in the profi le of North Island plants
might also be explained by its effi cient conversion to the hydroxylated derivative,
spathulenol. The authors reported that the concentration of spathulenol was higher
in the North Island plants, which is in accord with the more effi cient utilization of
its precursor. It is not possible to conclude much on the ester differences other than
that it is possible that either or both of the precursor fragments could be lacking.
The authors noted as well that plants from the South Island also had the phytosterols
campestrol and stigmastrol; no comments on that apparent difference were offered.
2.2.6 Leptospermum scoparium (Myrtaceae)
Leptospermum scoparium J.R. & F. Forst, known by the Maori name “manuka,”
occurs widely throughout New Zealand. Owing to the potential of manuka as an oilproducing
species, Perry et al. (1997a) investigated the steam-volatile components
of specimens representing much of its range in New Zealand as well as specimens
grown in a common garden. Gas chromatographic analysis of the distillates from
15 sites showed some 50 or so peaks that represented three groups of compounds,
monoterpenes, sesquiterpenes, and “triketones.” Three chemotypes emerged from
these analyses that agreed reasonably well with morphological differences that
had been noted earlier (unpublished observations of W. Harris cited in the current
paper). A northern chemotype was distinguished on the basis of its high concentration
of α-pinene, an East Cape chemotype was characterized by the presence of
high concentrations of the triketones leptospermone [50], isoleptospermone [51],
and fl avesone [52] (see Figs. 2.10 and 2.11 for structures 50–52), and a southern