Abstract
The potent α-glucosidase inhibitor (compound I) was isolated from coffee brews by the activity-based fractionation and identified as a β-carboline alkaloid norharman (9H-pyrido[ 3.4-b]indole) on the basis of mass spectroscopy and nuclear magnetic resonance spectra ((1)H NMR, (13)C NMR, and COSY). The norharman showed a potent inhibition against α-glucosidase enzyme in a concentration dependent manner with an IC50 value of 0.27 mM for maltase and 0.41 mM for sucrase, respectively. A Lineweaver-Burk plot revealed that norharman inhibited α-glucosidase enzyme uncompetitively, with a Ki value of 0.13 mM.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Carbolines / metabolism*
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Coffee / chemistry*
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Glycoside Hydrolase Inhibitors / chemistry*
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Glycoside Hydrolase Inhibitors / isolation & purification*
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Glycoside Hydrolase Inhibitors / pharmacology
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Hypoglycemic Agents / chemistry
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Hypoglycemic Agents / isolation & purification
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Hypoglycemic Agents / pharmacology
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Magnetic Resonance Spectroscopy
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Mass Spectrometry
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Sucrase / antagonists & inhibitors
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alpha-Glucosidases / metabolism*
Substances
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9H-pyrido(3.4-b)indole
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Carbolines
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Coffee
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Glycoside Hydrolase Inhibitors
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Hypoglycemic Agents
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alpha-Glucosidases
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Sucrase