Biology Reference
In-Depth Information
1
2
) were found to be responsible for the rat
intestinal
a
-glucosidase inhibition activity of the ethanol extract of Azuki
may enable their interaction with the active sites of the enzyme. The activity
is highly dependent on the position of the glycosyl moieties as
Vitexin (
) and isovitexin (
(IC
50
,
0.4 mg/mL or 926
m
M) gave much stronger inhibition activity than
1
2
(IC
50
, 4.8 mg/mL or 11 mM). Such a low inhibitory activity of
2
makes them unattractive for potential usage as active ingredients in foods.
Saponarin (
1
and
) isolated from the leaves of
Tinospora cordifolia
showed inhi-
a
-glucosidase, yeast invertase, rat intestinal maltase, and sucrase, respec-
tively. In addition, saponarin showed mixed-type inhibition on activities
of different enzyme origins. Other than the leaves of
T. cordifolia
, saponarin
was also reported to be present appreciably in barley leaves (
Ohkawa et al.,
1998; Saunders & McClure, 1973
)
, some mosses
(
Basile, Sorbo, Lopez-
Biskup, 2007
).
5,7,3
0
,4
0
-Tetramethoxyflavone (
3
), 5,7,4
0
-trimethoxyflavone (
4
5
), and
3,5,7,3
0
,4
0
-pentamethoxyflavone (
) isolated from rhizomes of
Kaempferia
parviflora
, a Zingiberaceae family plant, were used as a traditional herb in
the northeast of Thailand. The IC
50
values of 20.4, 54.3, and 64.3
m
Min
inhibition of
a
-glucosidase catalyzed hydrolysis of 4-methylumbelliferyl
their inhibition mechanisms and inhibitory activity when natural substrate
maltose was used remains to be studied.
Quercetin (
6
) inhibited the activity of yeast
a
-glucosidase with IC
50
values of 530 and 160
m
M, respectively, as mea-
sured by pNPG assay (
Escand´n-Rivera et al., 2012
). The Lineweaver-Burk
and Dixon plots show that isorhamnetin is a mixed-type
a
-glucosidase
inhibitor with a large
K
i
value of 1.91 mM. Previously, Xu proposed that
7,3,3
0
,4
0
hydroxy groups in the flavonoid core were important structure fea-
based on the results obtained from Sonia et al., 3
0
substituent is not relevant
for better activity against the enzyme since
7
) and isorhamnetin (
8
with a 3
0
methoxy group was
8
possessing a 3
0
hydroxy moiety. Another research group
also measured the inhibition activity of quercetin and its glucoside,
isoquercetin and rutin, which exhibited yeast
a
-glucosidase inhibition activity
more active than
7
