Biology Reference
In-Depth Information
al.
, 1991) (3,6-digalloyl; 2,4-DHHDP-type). Isoterchebin (
27
), which
was isolated from
Cytinus hypocistis
(Fürstenwerth and Schildknecht,
1976) and from
Cornus officinalis
(Okuda
et al
., 1981), is an exceptional
example of dehydroellagitannins because, unlike most compounds in this
ellagitannin subclass, its glucopyranose core adopts the
4
C
1
conformation
instead of the
1
C
4
or skewed-boat conformation.
Table 2.2 Modified dehydroellagitannins and their plant sources
Compound
Plant source
Family
Chebulagic acid (
28
)
Terminalia chebula
Combretaceae
Chebulinic acid
Terminalia chebula
Combretaceae
Macarinin B (
29
)
Macaranga sinensis
Euphorbiaceae
Macaranin A (
30
)
Macaranga sinensis
Euphorbiaceae
Eumaculin E (
31
)
Euphorbia maculata
Euphorbiaceae
Phyllanthusiin A (
32
)
Phyllanthus flexuosus
Euphorbiaceae
Phyllanthusiin B (
33
)
Phyllanthus flexuosus
Euphorbiaceae
Phyllanthusiin C (
34
)
Phyllanthus flexuosus
Euphorbiaceae
Repandusinic acid A (
35
)
Mallotus repandus
Euphorbiaceae
Mallotinin (
36
)
Mallotus japonicus
Euphorbiaceae
Bixanin (
37
)
Euphorbia thymifolia
Euphorbiaceae
Amariinic acid (
38
)
Phyllanthus amarus
Euphorbiaceae
Ascorgeraniin (
39
)
Elaeocarpus sylvestris
Elaeocarpaceae
(= Elaeocarpusin)
Geranium thunbergii
Geraniaceae
Putranjivain A (
40
)
Macaranga sinensis
Euphorbiaceae
Geraniinic acid B (
41
)
Geranium thunbergii
Geraniaceae
Euphormisin M
2
(
42
)
Euphorbia humifusa
Euphorbiaceae
2.1.3 Modified dehydroellagitannins
Chebulagic acid (
28
, Yoshida
et al.
, 1980), isolated from myrobalans
(
i.e.
, fruits of
Terminalia chebula
, see Fig. 1.11 in Chapter 1) in an early
study on tannin chemistry, has a chebuloyl group, which is likely a
metabolite produced by a benzylic acid rearrangement-like cleavage of
the cyclohexenetrione ring of the DHHDP group (see Chapter 1). The
chebuloyl group is also found in the macarinin B (
29
) and macaranin A
(
30
) molecules, both isolated from
Macaranga sinensis
(Lin
et al.
,
1990). Ellagitannins possessing an acyl unit related to the chebuloyl
group have been found in
Geranium thunbergii
and in many species of
Euphorbiaceae
that produce geraniin (
19
) as the major tannin. It is
