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Inhibitory Effects of Pomegranate Extracts on Recombinant Human Maltase–Glucoamylase
Author(s) -
Kawakami Kayoko,
Li Peng,
Uraji Misugi,
Hatanaka Tadashi,
Ito Hideyuki
Publication year - 2014
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/1750-3841.12568
Subject(s) - aril , acarbose , chemistry , polyphenol , alpha glucosidase , ic50 , biochemistry , maltase , food science , traditional medicine , enzyme , in vitro , antioxidant , medicine
α‐Glucosidase inhibitors are currently used in the treatment of type 2 diabetes. In this study, we investigated the inhibitory activities of aril and pericarp extracts from pomegranates obtained various regions against recombinant human maltase–glucoamylase (MGAM). The inhibitory activities of the aril extracts tended to be stronger than those of the pericarp extracts. The Iranian aril extract was the most effective inhibitor. We investigated the polyphenol content of the pomegranate extracts using the Folin–Ciocalteu method. Among the aril extracts, the Iranian aril extract showed the highest polyphenol content. We further evaluated inhibitory activity against α‐glucosidase from the rat small intestine. Pomegranate extract used in this study showed slightly different inhibitory activities according to α‐glucosidase origin. Iranian aril extract was the most effective inhibitor of α‐glucosidases, especially recombinant human MGAM. Bioassay‐guided fractionation of the pomegranate arils led to identification of punicalagin and oenothein B as potent inhibitors of α‐glucosidase. Oenothein B showed inhibitory activity with a half‐maximal inhibitory concentration (IC 50 ) value of 174 μM. Its potency was comparable to that of the α‐glucosidase inhibitor acarbose with an IC 50 value of 170 μM. Dixon plot kinetic analysis of oenothein B showed a noncompetitive inhibition with a K i value of 102 μM. These results suggest that pomegranate arils would be useful for suppressing postprandial hyperglycemia.