title: Molecular recognition of rosmarinic acid from Salvia sclareoides extracts by acetylcholinesterase: a new binding site detected by NMR spectroscopy.
abstract: Acetylcholinesterase (AChE) inhibition is one of the most currently available therapies for the management of Alzheimer's disease (AD) symptoms. In this context, NMR spectroscopy binding studies were accomplished to explain the inhibition of AChE activity by Salvia sclareoides extracts. HPLC-MS analyses of the acetone, butanol and water extracts eluted with methanol and acidified water showed that rosmarinic acid is present in all the studied samples and is a major constituent of butanol and water extracts. Moreover, luteolin 4'-O-glucoside, luteolin 3',7-di-O-glucoside and luteolin 7-O-(6''-O-acetylglucoside) were identified by MS(2) and MS(3) data acquired during the LC-MS(n) runs. Quantification of rosmarinic acid by HPLC with diode-array detection (DAD) showed that the butanol extract is the richest one in this component (134 μg mg(-1) extract). Saturation transfer difference (STD) NMR spectroscopy binding experiments of S. sclareoides crude extracts in the presence of AChE in buffer solution determined rosmarinic acid as the only explicit binder for AChE. Furthermore, the binding epitope and the AChE-bound conformation of rosmarinic acid were further elucidated by STD and transferred NOE effect (trNOESY) experiments. As a control, NMR spectroscopy binding experiments were also carried out with pure rosmarinic acid, thus confirming the specific interaction and inhibition of this compound against AChE. The binding site of AChE for rosmarinic acid was also investigated by STD-based competition binding experiments using Donepezil, a drug currently used to treat AD, as a reference. These competition experiments demonstrated that rosmarinic acid does not compete with Donepezil for the same binding site. A 3D model of the molecular complex has been proposed. Therefore, the combination of the NMR spectroscopy based data with molecular modelling has permitted us to detect a new binding site in AChE, which could be used for future drug development.
authors.affiliation: Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciênias da Universidade de Lisboa, Ed. C8, 5° Piso, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: Filipa
authors.initials: F
authors.lastname: Marcelo
authors.forename: Catarina
authors.initials: C
authors.lastname: Dias
authors.forename: Alice
authors.initials: A
authors.lastname: Martins
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Madeira
authors.forename: Tiago
authors.initials: T
authors.lastname: Jorge
authors.forename: M Helena
authors.initials: MH
authors.lastname: Florêncio
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Cañada
authors.forename: Eurico J
authors.initials: EJ
authors.lastname: Cabrita
authors.forename: Jesús
authors.initials: J
authors.lastname: Jiménez-Barbero
authors.forename: Amélia P
authors.initials: AP
authors.lastname: Rauter
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy*; D001665:Binding Sites; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D002934:Cinnamates / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D053630:Depsides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D000077265:Donepezil; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D007189:Indans / Q000493:pharmacokinetics / Q000627:therapeutic use; D047311:Luteolin / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D008958:Models, Molecular; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010880:Piperidines / Q000493:pharmacokinetics / Q000627:therapeutic use; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D011174:Portugal; D027544:Salvia / Q000737:chemistry*; D000097123:Rosmarinic Acid
chemical_list: D002800:Cholinesterase Inhibitors; D002934:Cinnamates; D053630:Depsides; D000077265:Donepezil; D005960:Glucosides; D007189:Indans; D047311:Luteolin; D010880:Piperidines; D010936:Plant Extracts; D000097123:Rosmarinic Acid; C585087:luteolin 3',7-di-O-glucoside; C120646:luteolin 4'-O-glucoside; C585086:luteolin 7-O-(6''-O-acetylglucoside)