Ellagitannins Renewed the Concept of Tannins - Chemistry and Biology of Ellagitannins - page 47

et al ., 1985). Geraniin was also found to suppress the increase of lipid
peroxide level in the serum caused by inhalation of carbon tetrachloride.
The effects of tannins as evaluated via oral administration are
particularly worthy of further investigation. The oral administration of
geraniin-rich extract of Geranium thunbergii significantly lowered the
lipid peroxide level in the serum and the liver of rats in which liver injury
was induced by feeding them with peroxidized oil. The levels of serum
cholesterol, GOT and GPT in the rats treated with peroxidized oil were
also reduced in the presence of geraniin (Kimura et al ., 1984).

1.7.5 Absorption and metabolism of ellagitannins in animals

The metabolic conversion of ellagic acid in animals into 3,8-
dihydroxybenzo-[b,d]pyran-6-one and related compounds was reported
in 1980 (Doyle and Griffiths, 1980). This compound and 3-hydroxy-6 H -
dibenzo[b,d]pyran-6-one were detected in the urine and serum of a sheep
that was fed with Terminalia oblongata leaves containing chebulagic
acid, punicalagin and teroblongin ( i.e. , 1-α- O -galloylpunicalagin). 3- O -
Glucuronide of 3-hydroxy-6 H -dibenzo[b,d]pyran-6-one was also isolated
from the urine and serum of the sheep (Okuda et al ., 1995). These
aspects and other related to the bioavailability of ellagitannins are
discussed in greater details in Chapters 7 and 8.

R OH

3,8-Dihydroxy-6 H -dibenzo[b,d]pyran-6-one : R = OH
3-Hydroxy-6 H -dibenzo[b,d]pyran-6-one : R = H

O

O

1.8 Bibliography

Amakura, Y., Miyake, M., Ito, H., Murakaku, S., Araki, S., Itoh, Y., Lu, C.-F., Yang, L.-
L., Yen, K.-Y., Okuda, T. and Yoshida, T. (1999). Acalyphidins M 1 , M 2 , and D 1 ,
ellagitannins from Acalypha hispida , Phytochemistry , 50, pp. 667-675.
Chen, L.-G., Yen, K.-Y., Yang, L.-L., Hatano, T., Okuda, T. and Yoshida, T. (1999).
Macrocyclic ellagitannin dimers, cuphiins D 1 and D 2 , and accompanying tannins
from Cuphea hyssopifolia , Phytochemistry , 50, pp. 307-312.
Doyle, B. and Griffiths, L. A. (1980). The metabolism of ellagic acid in the rat,
Xenobiotica , 10, p. 247-256.