Biology Reference
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Unlike the monomers, many oligomeric ellagitannins can be
valuable chemotaxonomic markers of plant systematic and evolutionary
relationships in dicotyledonous plants because of their structural
specificities. As described earlier, GOG-type oligomers with the
dehydrodigalloyl (DHDG) unit are found in the Rosaceae , Coriariaceae ,
Nymphaeaceae , and Tamaricaceae , and the position and configuration of
the DHDG unit seems to be specific to each family. The configurations
of the DHDG unit on each anomeric center of the dimers in rosaceous
plants (Okuda et al ., 1984b) are α and α, while those in coriariaceous
plants (Hatano et al ., 1986) are α and β. Dimers such as 61 and 62 in the
Nymphaeaceae and Tamaricaceae , which are produced via a similar
coupling mode between the galloyl groups at C-1 of one monomer and
C-2 of the other monomer, are made of different constituting monomers,
i.e. , 3,6-HHDP-1,2,4-trigalloyl-α- D -glucose in the Nymphaeaceae and
tellimagrandin II ( 1 ) in the Tamaricaceae . These structural features may
be of chemotaxonomic significance.
a
HO
OH
HO
OH
OH
HO
OH
HO
OH
OH
HO
HO
O
OH
O
OH
O
HO
O
OH
O
O
O
O
O
OH
O
O
O
HO
O
O
O
O
O
HO
O
b
O
O
O
O
HO
HO
OH
HO
OH
HO
OH
OH
OH
HO
OH
Pterocaryanin C ( 113 )
Casuarictin ( 4 )
b
a
Nobotanin B ( 78 )
Nobotanin F ( 71 )
The geraniin-related dimers that bear a valoneoyl group or its isomer
as the linking unit have been found only in herbaceous and woody
euphorbiaceous plants, hence serving as characteristic markers of the
family. The structural features of the DOG-type oligomers up to
pentamers in the Melastomataceae are unique, for they are composed of
two different monomeric units [ i.e. , casuarictin ( 4 ) and pterocaryanin C
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