Biology Reference
In-Depth Information
OH
Ar
Ar
Ar
OH
OH
OH
O
OH
O
O
O
HOH
2
C
O
O
n
O
HO
O
O
OH
OH
OH
OH
HO
HO
O
O
O
OH
OH
O
HO
OH
or
OH
OH
Ar
=
HO
OH
HO
n
= 0-50
OH
OH
HO
Hydrolyzable tannin
Condensed tannin (B type)
Figure 3.1 Chemical structures for hydrolyzable tannin and condensed tannin (B type).
agents, and inhibitors for enzymes including
a
-glucosidase and
a
-amylase.
two main classes of polyphenolic compounds are capable of interaction with
proteins through nonspecific binding and thus often purposefully removed
with carrying out screening of natural products for enzyme inhibition
activity. The interaction with protein positively correlated with higher
molecular weight and degree of polymerization. There are a number of
hydrolyzable tannins isolated show potent inhibition activity on yeast
Li, Yuan, & Seeram, 2012
)
and rugosin D, rugosin A, and Tellimagrandin
II from rose flower grown in Xinjiang province, China. These compounds
show much higher inhibition activity toward microbial
a
-glucosidase than
if they are effective when combined with food matrix (such as rice and flour)
where proteins are abundant and nonspecific binding becomes a major factor.
Condensed tannins or oligomeric proanthocyanidins were shown to be
potent inhibitors of
a
-glucosidase. Their inhibition activity is higher with
high degree of polymerization, which is consistent with the notion that
the inhibition may be due to nonspecific binding with proteins (
Lee,
Cho, Tanaka, & Yokozawa, 2007
)
. In human digestion tract, there are pro-
teases that can hydrolyze the proteins and may be able to release the
proanthocyanidins bound on protein once they are hydrolyzed. This
hypothesis needs to be evaluated in simulated digestion conditions where
pancreatic juice or related proteases can be added together to mimic the
in vivo
digestion conditions. Proanthocyanidins are abundant in plant king-
dom and would be a highly attractive active ingredient for low GI foods
