Biology Reference
In-Depth Information
In addition, the reaction of geraniin with thiol compounds, such as
glutathione or
N
-acetyl cysteine, gave thioethers of the chebuloyl group,
which were further accompanied by a second thioether of the
cyclopentane carboxyl moiety (Fig. 4.14) (Tanaka
et al.
, 1996). The
former product was reductively converted into chebulagic acid (1-
O
-
galloyl-3,6-(
R
)-HHDP-2,4-chebuloyl-β-
D
-glucose), a major ellagitannin
of
Terminalia chebula
(Schmidt and Nieswandt, 1950)
and
Phyllanthus
embrica
(Zhang
et al.
, 2001). Another thioether derivative with a
cyclopentane carboxyl structure is spontaneously decomposed to give an
ellagitannin with α-ketocarboxyl groups. This product was structurally
related to a naturally occurring ellagitannin, euphormisin M
2
, which is
isolated from
Euphorbia
sp. (Yoshida
et al.
, 1994).
Fig. 4.14 Conversion of the DHHDP group into a chebuloyl group.
