title: Structure activity relationships of flavonoids as potent alpha-amylase inhibitors.
abstract: The effects of three flavonoids (quercetin, luteolin, diosmetin) on alpha-amylase were examined by enzymatic kinetics and fluorescence spectroscopy. The three test flavonoids were non-competitive inhibitors of the enzyme. Addition of flavonoids led to fluorescence quenching of alpha-amylase. The quenching was initiated from the formation of a complex between the flavonoids and the enzyme, corresponding to a static quenching process. An alpha-amylase molecule provides a binding site for the test flavonoid. The main binding force was hydrophobic. The decreasing order of inhibition of alpha-amylase by flavonoids and the binding force was luteolin, diosmetin, and quercetin. It is demonstrated that hydroxylation in ring C and methylation of the hydroxyl group in ring B of flavonoids may weaken the binding affinities to alpha-amylase.
authors.forename: Erdong
authors.initials: E
authors.lastname: Yuan
authors.forename: Benguo
authors.initials: B
authors.lastname: Liu
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Wei
authors.forename: Jiguo
authors.initials: J
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Qiong
authors.initials: Q
authors.lastname: Li
mesh_terms: D004791:Enzyme Inhibitors / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D013329:Structure-Activity Relationship; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000737:chemistry
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D000516:alpha-Amylases