Biology Reference
In-Depth Information
1.3.7 Seasonal transformations of ellagitannins in a plant
While the ellagitannin structures occurring in a plant species are
generally invariable throughout a year, as observed for geraniin in
Geranium
species, seasonal structural change of main tannins occurs in
some woody plants. An example is the seasonal transformations of gallo-
and ellagitannins in
Liquidambar formosana
. Tellimagradins, casuarictin
and gallotannins, which are abundant in young leaves in April, are
replaced by casuarinin by July, and the latter, together with
pedunculagin, are the main tannins in the leaves from summer to autumn
until the leaves fall down. This seasonal transformation, which
interestingly parallels the oxidative biogenetic route followed by
ellagitannin structures, is depicted above (Fig. 1.8, Okuda
et al
., 1987).
1.3.8 Production of ellagitannins by tissue cultures
The callus and shoot cultures of
Hetrocentron roseum
, under
illumination with fluorescent lamps, produce large amounts of
casuarictin (a
C
-glycosidic monomer) and nobotanin M (a dimer)
(Yazaki and Okuda, 1990). Oenothein B and other macrocyclic dimers
were produced by callus culture of
Oenothera laciniata
and shoot tissue
culture of
O. tetraptera
(Taniguchi
et al
., 1998, 2002). Geraniin and
other ellagitannins were accumulated by
Aleurites fordii
callus culture
(Taniguchi
et al
., 2002).
1.4 Correlation of Ellagitannins of Various Oxidation Stages with
Plant Evolution Systems
1.4.1 Classification of hydrolyzable tannins based on the oxidation
stages of their polyphenolic functions
Hydrolyzable tannins of various biogenetic oxidative stages can be
classified into types I to IV according to the degree of oxidation of their
polyphenolic groups. The different polyphenolic groups and examples of
compounds of each type are as follows (Okuda
et al
., 2000):
