Biology Reference
In-Depth Information
stomach. At this moment, such potent and food grade inhibitors are lacking.
Acarbose and certain glycomimetics are the exception.
4.2. Low GI starchy foods containing starch
hydrolase inhibitors
Low GI starchy food could be found naturally or made by addition of starch
hydrolase inhibitors. Natural low GI food could be due to the presence of
considerable amount of resistant starch, or food inherently containing some
antidiabetic compounds. Herein, we summarized the research progress on
low GI starchy foods naturally containing bioactive compounds and the
starchy foods fortified with botanical extracts.
4.2.1 Sweet potato
Some types of sweet potato (
Ipomoea batatas
) are found to be beneficial to dia-
betes patients. For example, purple sweet potato,
I. batatas
cv. Ayamurasaki
(YGM), contents high amount of anthocyanins which have antidiabetic
effects. Matsui et al. found out that anthocyanin extracts from YGM root
had potent maltase inhibitory activitymeasured using
a
-glucosidase inhibition
assay to have IC
50
of 0.36 mg/mL. YGM extract also inhibited
a
-amylase
were later isolated from YGM extract and identified as diacylated antho-
cyanins (YGM3 and YGM-6). Yet they are not particularly potent inhibitors
judging from the high IC
50
values of 0.239 mg/mL for YGM3 and 0.245
mg/mL for YGM-6. YGM3 and YGM6 are cyanidin and peonidin [3-
O
-(2-
O
-(6-
O
-
E
-Fer-ß-
D
-glucopyranosyl)-6-
O
-
E-
Caf-ß-
D
-glucopyranoside)-
male rats were fed with diacylated anthocyanin (100 mg/kg) followed
by maltose (2 g/kg), a maximal blood glucose level at 30 min was
significantly decreased by 16.5% in comparison with untreated one.
A reduction of serum insulin secretion was also observed corresponding
to the decrease in blood glucose level. No significant change in blood
glucose concentrationwas observedwhen sucrose or glucose was ingested,
suggesting that the antihyperglycemic effect of the anthocyanin was
achieved by maltase inhibition, not by sucrase or glucose transport inhibi-
tion at the intestinal membrane (
Matsui et al., 2002
)
.
4.2.2 Cinnamon
Cinnamon is used as a flavor ingredient in food preparation. It has an addi-
tional role in type 2 diabetes prevention. Procyanidin oligomers in cinnamon
