Biology Reference
In-Depth Information
C-1-linked galloyl-derived unit is either part of a terarylic
nonahydroxyterphenoyl (NHTP) unit (also known as a flavogalloyl
group) that is attached
via
three ester bonds to the 2-, 3- and 5-positions
of the glucose core, as exemplified in the structures of vescalagin (
1
) and
castalagin (
2
), or part of a biarylic variant bridging the 2- and 3-positions
of the glucose core, as exemplified in the structures of stachyurin (
3
) and
casuarinin (
4
) (Fig. 9.1). The latter biarylic unit is commonly referred to
as “HHDP” for hexahydroxydiphenoyl, but we prefer to use the acronym
“HHBP” for hexahydroxybiphenoyl to signify more explicitly the
biarylic nature of this ellagitannin unit type (Quideau
et al.
, 2004).
HHBP unit
HO
HO
HO
OH
HO
OH
HO
HO
O
O
HO
O
O
HO
O
O
HO
2
O
O
R
1
HO
1
3
2
O
R
1
1
5
3
O
O
2'
O
1'
O
O
OH
O
O
1'
O
O
OH
2'
HO
O
HO
O
OH
4'
NHTP unit
HO
OH
OH
HO
OH
HO
OH
HO
OH
HO
HHBP unit
HO
OH
HO
1
: R
1
=
β
-OH, vescalagin
2
: R
1
=
α
-OH, castalagin
3
: R
1
=
β
-OH, stachyurin
4
: R
1
=
α
-OH, casuarinin
Fig. 9.1 Typical examples of monomeric
C
-glycosidic ellagitannins.
Ellagitannins of the
C
-glycosidic type have been found in various
plant species from the
Hamamelidaceae
,
Fagaceae
,
Betulaceae
,
Casuarinaceae
,
Juglandaceae
and
Rhoipteleaceae
families in the
Hamamelidae
subclass, from the
Rosaceae
,
Combretaceae
,
Lythraceae
,
Melastomataceae
,
Myrtaceae
,
Punicaceae
,
Trapaceae
and
Elaeagnaceae
families in the
Rosidae
subclass, and from the
Theaceae
and
Stachyuraceae
families in the
Dilleniidae
subclass (Okuda
et al.
, 1993,
2000, Okuda, 2005).
