Biology Reference
In-Depth Information
isolated ellagitannins generally remain intact when in contact with air.
The various biological and pharmacological properties of these tannins
can be determined for each individual compound.
HO
OH
HO
OH
HO
OH
O
O
OH
O
O
O
OH
Geraniin
O
O
OH
O
O
O
O
H
O
H
O
HO
O
HO
O
OH
OH
HO
OH
OH
O
OH
HO
OH
O
1.1.2 Definition of ellagitannins in the narrow and wider senses
Geraniin (Okuda
et al.
, 1976, 1982a) can be regarded as a keystone in the
ellagitannin biooxidation process, since it is structurally classified as a
dehydroellagitannin that is located at a junction in the biogenesis of the
whole ellagitannin family. Geraniin has also been found in several
oligomeric molecules as a composing monomer. Rapid developments
were made in the field of ellagitannin chemistry after the discovery of
geraniin, leading to the isolation of others dehydroellagitannins, as well
as products of further biogenetic oxidation, and also oligomers, up to
pentamers (Yoshida
et al
., 1999, 2005).
While several ellagitannins had been isolated from the fruits of
Terminalia chebula
(
i.e.
, myrobalans) since 1947 (Schmidt and Mayer,
1956), and also from
Castanea
and
Quercus
species of the
Fagaceae
family (Mayer, 1971), new techniques of isolation, spectroscopy and
biological screening (Okuda
et al
., 1989a) enabled in more recent years
rapid developments, which notably helped with the partial revision of
some of their structures (Okuda
et al
., 1980a, Yoshida
et al
., 1980).
Furthermore, these in-depth investigations also served to gather
important insights on plant genealogy, for the structural diversity thus
unveiled about ellagitannins was found to correlate to the evolution and
classification of the plants that contain them (Okuda
et al
., 2000).
