title: Inhibition of type A monoamine oxidase by coptisine in mouse brain.
abstract: The inhibitory effects of coptisine, a protoberberine isoquinoline alkaloid, on type A and type B monoamine oxidase (MAO-A and MAO-B) activities in mouse brain were investigated. Coptisine showed an inhibitory effect on MAO-A activity in a concentration-dependent manner using a substrate kynuramine, but coptisine did not inhibit MAO-B activity. Coptisine exhibited 54.3% inhibition of MAO-A activity at 2 microM. The values of Km and Vmax of MAO-A were 151.9 +/- 0.6 microM and 0.40 +/- 0.03 nmol/min/mg protein, respectively (n=5). Coptisine competitively inhibited MAO-A activity with kynuramine. The Ki value of coptisine was 3.3 microM. The inhibition of MAO-A by coptisine was found to be reversible by dialysis of the incubation mixture. These results suggest that coptisine is a potent reversible inhibitor of MAO-A, and that coptisine functions to regulate the catecholamine content.
authors.affiliation: College of Pharmacy, Chungbuk National University, Chengju, Republic of Korea.
authors.forename: J S
authors.initials: JS
authors.lastname: Ro
authors.forename: S S
authors.initials: SS
authors.lastname: Lee
authors.forename: K S
authors.initials: KS
authors.lastname: Lee
authors.forename: M K
authors.initials: MK
authors.lastname: Lee
mesh_terms: D000818:Animals; D001599:Berberine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D001600:Berberine Alkaloids / Q000737:chemistry; D001667:Binding, Competitive; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D003010:Clorgyline / Q000494:pharmacology; D003956:Dialysis; D004305:Dose-Response Relationship, Drug; D007490:Iproniazid / Q000494:pharmacology; D007735:Kynuramine / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D001600:Berberine Alkaloids; D008996:Monoamine Oxidase Inhibitors; C034384:coptisine; D001599:Berberine; D007735:Kynuramine; D007490:Iproniazid; D008995:Monoamine Oxidase; C005413:palmatine; D003010:Clorgyline