title: Α-glucosidase inhibitor isolated from coffee.
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.
authors.affiliation: Department of Chemical and Biological Engineering, Seokyeong University, Seoul 136-704, Republic of Korea.
authors.forename: Shin Duk
authors.initials: SD
authors.lastname: Kim
mesh_terms: D002243:Carbolines / Q000378:metabolism*; D003069:Coffee / Q000737:chemistry*; D065089:Glycoside Hydrolase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D013393:Sucrase / Q000037:antagonists & inhibitors; D000520:alpha-Glucosidases / Q000378:metabolism*
chemical_list: C000603590:9H-pyrido(3.4-b)indole; D002243:Carbolines; D003069:Coffee; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D000520:alpha-Glucosidases; D013393:Sucrase