Biology Reference
In-Depth Information
2.1.1 Primary ellagitannins (HHDP esters)
In addition to the basic ellagitannins 1 and 4 , which have a 4 C 1 glucose
core, and their deacylated congeners, strictinin ( 2 ), gemin D ( 3 ),
pedunculagin ( 5 ), and isostrictinin ( 6 ) (Okuda et al. , 1980b, 1983,
Yoshida et al. , 1985), many naturally occurring analogs exist, such as
rugosins A ( 10 ) and B ( 11 ) (Hatano et al. , 1990a), tirucallin A ( 12 ,
Yoshida et al. , 1991b), cornusiin B ( 13 , Okuda et al. , 1984a), praecoxins
C ( 14 ) and D ( 15 ) (Hatano et al. , 1991) and tergallagin ( 16 , Tanaka
et al. , 1986a), in which a HHDP or a galloyl group is replaced by a
valoneoyl, a depsidone, a tergalloyl, or a gallagyl group.
HO
OH
HO
HO
HO
OH
HO
O
OH
HO
Tircallin A ( 12 ): R = ( β )-OG
Cornusiin B ( 13 ): R = OH
HO
COOH
HO
O
O
O
HO
O
O
HO
O
O
GO
O
HO
O
O
R
O
R
O
O
O
O
OH
OG
G
HO
Rugosin A ( 10 ): R = ( β )-OG
Rugosin B ( 11 ): R = OH
O
HO
HO
OH
O
OH
OH
O
HO
OH
HO
O
OH
OH
OH
O
HO
HO
O
O
O
O
HO
O
Praecoxin C ( 14 ): R = ( β )-OG
Praecoxin D ( 15 ): R = OH
O
O
O
HO
HO
O
O
OH
O
O
OH
OH
HO
HO
O
O
O
O
O
R
O
O
HO
HO
O
O
O
HO
OH
O
OH
HO
HO
Tergallagin ( 16 )
OH
OH
OH
HO
OH
HO
O
O
OH
The tannins possessing a valoneoyl group or its regioisomer, the
tergalloyl group, may be produced by the catabolism of oligomeric
ellagitannins in a plant ( vide infra ). However, the possibility that they
could be formed in an anabolic manner through oxidative coupling of the
O
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