Biology Reference
In-Depth Information
Although this report used pNPG assay, the IC
50
values for quercetin are about
30 times lower than the previous report. Unfortunately, it is hard to pinpoint
the actual cause of the difference without a reference standard used in both
studies. This is the drawback of IC
50
values, which are highly dependent
on experimental conditions and enzyme activity in the actual assays. Appar-
ently, substituting the 3-OH group with glycosyl moiety greatly decreased
the inhibition activity by over 10 times. A structurally similar compound,
myricetin-3-
O
-rhamnoside (
)showed
much stronger yeast
a
-glucosidase inhibition activity with IC
50
values of 1.1
with caution because the possibly different experimental conditions applied
and the lack of a reference standard.
Four isoprenylated flavanes, kazinol A (
9
) and europetin-3-
O
-rhamnoside (
10
)
were isolated from the roots of paper mulberry
Broussonetia papyrifera via
bioassay-
guided fractionation (
Ryu et al., 2010
)
. They show strong inhibition activity
on yeast
a
-glucosidase with IC
50
values of 12 and 26.3
m
M. The structural
change from
11
) and its derivative kazinol B (
12
seems to have a big impact on its activity. Prenylated quer-
cetin derivatives, 8-(1,1-dimethylallyl)-5
0
-(3-methylbut-2-enyl)-3
0
,4
0
,5,7-
tetrahydroxyflavonol (
11
to
12
13
) and its isomer papyriflavonol A (
14
) are much more
active with IC
50
of 3.6 and 2.1
m
M as mixed inhibitors.
) was identified in the leaves of soybean (
Glycine max
), and it
was found to be the most potent component in the inhibition activity on
IC
50
value of 6
m
M. However, there is no data for its inhibition activity for
mammal
a
-glucosidase. Dolichandroside A (
15
)
isolated from heartwood of
Dolichandrone falcata
showed inhibition activity
values for
16
) and aloe saponarin II (
17
were 61 and 71.3
m
M for yeast
a
-glucosidase, respec-
tively. For rat intestinal
a
-glucosidase, IC
50
values were 28.7 and 34.5
m
M,
respectively.
Hispidin (
18
), hispolon (
19
), and inotilone (
20
) were isolated from the
fruiting body of
Phellinus merrillii
, which is a mushroom and is commonly
called “Sangwhang” in Taiwan (
Huang et al., 2011
). Compounds
16
and
17
19
and
20
exhibited very potent inhibition activity on
a
-glucosidase with IC
50
values of 56.3 and 85.4
m
M. In contrast,
18
showed much weaker inhibition
activity with an IC
50
value of 1.2 mM.
