Starch Hydrolase Inhibitors from Edible Plants - Advances in Food and Nutrition Research - page 124

belongs to Myrtaceae family. Hu, Luo, Li, Joshi, and Lu (2012) isolated and
purified 2 0 4 0 -dihydroxy-6 0 -methoxy-3 0 5 0 -dimethylchalcone (DMC) from
the dried flower buds of C. operculatus . The compound displayed a non-
competitive inhibitory mechanism toward PPA ( Hu et al., 2012) .
Tiliroside (

)( Fig. 3.8 ) , isolated from the seeds of dog rose, Rosa canina
L., inhibits PPA with IC 50 of 280 mM, and kinetic study shows that it is a
noncompetitive inhibitor with K i values of 84.2 m M quantified using
p -nitrophenyl-alpha- D -pentaglucoside as a substrate. Unlike acarbose,
tiliroside shows no inhibition activity against a -glucosidase. Perhaps due
to its weak a -amylase inhibition activity in animal model, high-dosage
tiliroside (600 mg/kg) is needed to reduce the postprandial plasma glucose
concentration of mice treated with starch at 2 g/kg. Tiliroside may exhibit
antihyperglycemia through inhibition of both sodium-dependent glucose
transporter 1 and glucose transporter 2 mediated glucose uptake in
enterocytes ( Goto et al., 2012 ) .
Curcumin and its derivatives have been suggested to be multitargeting
compounds that have a very broad range of health benefits. As a potential
agent for mitigating starch digestion rates, bisdemethoxycurcumin (

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)
( Fig. 3.8 ) from the rhizome of Curcuma longa has HPA and PPA inhibition
activity with IC 50 values of approximately 25 m M using DNSA assay.
Kinetic study shows that it is an uncompetitive inhibitor of HPAwith appar-
ent K i of 3.0 m M ( Ponnusamy et al., 2012 ).
Mono- and disubstituted caffeoylquinic acids are the main polyphenolic
compounds found in green coffee beans. Due to the presence of three sec-
ondary hydroxyl groups in the quinic acid ring, there are three inter-
converting position isomers of monosubstituted caffeoylquinic acids and
three dicaffeoyl quinic acids, which were all purified from green coffee
beans. Their inhibition activity on PPA-I ( Narita & Inouye, 2011 ) were
measured using p -nitrophenyl-diglucoside, which produces p -nitrophenol
and maltose upon hydrolysis. It is remarkable that the inhibitory activity is
highly dependent on the position of caffeoyl groups in monocaffeoyl
quinic acid. 5-Caffeoylquinic acid (or commonly known as chlorogenic
acid) ( Fig. 3.8 ) has the higher inhibition activity with IC 50 of 80 m M, com-
pared to that of 4-caffeoylquinic acid (120 m M) and 3-caffeoylquinic acid
(230 m M). For the three dicaffeoyl quinic acid isomers, the inhibitory
activity is much higher and are not as sensitive to the position of the ester
groups because 3,4- and 4,5-dicaffeoyl quinic acids ( Fig. 3.8 ) have the same
IC 50 values (20 mM), and 4,5-dicaffeoyl quinic acid has IC 50 of 30 m M
( Narita & Inouye, 2011 ) .

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