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revealed similarities between both β-PGG and
81
, with low levels of
TNFα generated at 4 hours and a maximum release at 24 hours (Fig.
6.16). However, the two tannins were observed to have considerably
different TNFα eliciting proficiency, as the dimeric species
81
was
found to be significantly more potent than β-PGG at every time point
examined.
OH
OH
OH
O
GO
O
OH
G =
GO
O
O
GO
O
OH
GO
O
HO
OG
OG
O
O
model
gallotannin/ellagitannin
hybrid
81
GO
GO
HO
OH
Fig. 6.15 Structures of an analogue of coriariin A.
14
12
10
TNF
α
(ng/mL)
8
6
4
PGG 66
Model Dimer 81
LPS
2
0
0
10
20
30
40
50
Time (hr)
Fig. 6.16 Time course for TNFα release from hPBMC's that were stimulated by β-PGG,
model dimer
81
, and LPS.
6.3.2 Structure/activity profile of ellagitannins and gallotannins
A comparison between the dose-response curves of the monomeric
gallotannin β-PGG (
66
) and the tannin dimers coriariin A (
62
) and
81
for
TNFα output after 24 hours of incubation with hPBMC's showed very
different responses. Therefore, the secretion of TNFα appears to be
responsive to the size of the tannin. The monomer β-PGG was less
