title: Inhibition of monoamine oxidase B (MAO-B) by Chinese herbal medicines.
abstract: Monoamine oxidase (MAO) catalyzes the oxidative deamination of biogenic amines accompaned by the release of H2O2. Two subtypes, MAO-A and MAO-B, exist on the basis of their specificities to substrates and inhibitors. The regulation of MAO-B activity is important in the treatment of neurodegenerative diseases. Twenty-seven species of plants used in traditional Chinese medicines, selected from an enthnobotanical survey, were used in an investigation of their inhibitory effect on MAO-B in rat brain homogenates. The 50% aqueous methanol extracts of four active extracts, Arisaema amurense, Lilium brownii var. colchesteri, Lycium chinense, and Uncaria rhynchophylla, exhibited the best activity and selectivity towards MAO-B with IC50 values of 0.44, 0.29, 0.40, and 0.03 mg/ml, respectively. A kinetic study of MAO-B inhibition by the four extracts using the Lineweaver-Burk plot for each active extract revealed the IC50 concentrations, and results show that: Ki = 0.59 mg/ml for A. amurense for the mixed-type mode, Ki = 0.58 mg/ml for L. brownii var. colchesteri for the mixed-type mode, Ki = 5.01 mg/ml for L. chinense for the uncompetitive mode, and Ki = 0.02 mg/ml for U. rhynchophylla for the uncompetitive mode. These may therefore be candidates for use in delaying the progressive degeneration caused by neurological diseases.
authors.affiliation: Department of Internal Medicine, Municipal Taipei Ho-Ping Hospital, Taiwan.
authors.forename: R D
authors.initials: RD
authors.lastname: Lin
authors.forename: W C
authors.initials: WC
authors.lastname: Hou
authors.forename: K Y
authors.initials: KY
authors.lastname: Yen
authors.forename: M H
authors.initials: MH
authors.lastname: Lee
mesh_terms: D000818:Animals; D031057:Arisaema; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D020128:Inhibitory Concentration 50; D027762:Lilium; D032305:Lycium; D008297:Male; D008995:Monoamine Oxidase / Q000187:drug effects*; D008996:Monoamine Oxidase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D008517:Phytotherapy; D010946:Plants, Medicinal; D051381:Rats; D017208:Rats, Wistar; D032070:Uncaria
chemical_list: D004365:Drugs, Chinese Herbal; D008996:Monoamine Oxidase Inhibitors; D008995:Monoamine Oxidase