Biology Reference
In-Depth Information
The DHHDP groups also react with
L-
cysteine methyl ester to give
unstable condensation products, which readily decompose to give the
corresponding hydrolysates in good yields. This is a convenient method
to selectively hydrolyze DHHDP bisesters (Tanaka
et al.
, 1992b). In
addition,
L
-cysteine reacts with DHHDP acetone adducts (Fig. 4.17)
(Tanaka
et al.
, 1992a). The fact that dehydroellagitannins readily react
with thiol compounds might have some biological significance, in
particular for euphorbiaceous plants, which accumulate these
ellagitannins.
OH
R
OH
HO
HO
HO
OH
HO
HO
HO
HO
HO
O
O
OH
O
OH
HO
O
O
O
O
O
O
1
HO
HO
O
O
O
O
OH
HO
O
HO
O
O
O
O
O
OH
HO
H
HO
O
O
O
O
O
HO
HO
OH
OH
OH
HO
R
HO
HO
HO
OH
OH
HO
OH
HO
HO
OH
HO
mongolicain A: R = H
psidinin A: R = OH
acutissimin A: R = H
eugenigrandin A: R = OH
HO
HO
O
OH
HO
O
O
O
HO
O
O
HO
O
O
O
OH
O
HO
H
O
H
O
HO
HO
O
HO
psiguavin
O
HO
OH
O
HO
Fig. 4.18 Structures of some oxidized
C
-glycosidic ellagitannins.
4.3.5 Additional oxidation reactions of HHDP and related acyl
groups
The oxidative metabolism of HHDP and related acyl groups is also
observed in
C
-glycosidic ellagitannins. Typical examples can be found in