title: Solid-phase synthesis and insights into structure-activity relationships of safinamide analogues as potent and selective inhibitors of type B monoamine oxidase.
abstract: Safinamide, (S)-N2-{4-[(3-fluorobenzyl)oxy]benzyl}alaninamide methanesulfonate, which is in phase III clinical trials as an anti-Parkinson drug, and a library of alkanamidic analogues were prepared through an expeditious solid-phase synthesis and evaluated for their monoamine oxidase B (MAO-B) and monoamine oxidase A (MAO-A) inhibitory activity and selectivity. (S)-3-Chlorobenzyloxyalaninamide (8) and (S)-3-chlorobenzyloxyserinamide (13) derivatives proved to be more potent MAO-B inhibitors than safinamide (IC50 = 33 and 43 nM, respectively, vs 98 nM) but with a lower MAO-B selectivity (SI = 3455 and 1967, respectively, vs 5918). The highest MAO-B inhibitory potency (IC50 = 17 nM) and a good selectivity (SI = 2941) were displayed by (R)-21, a tetrahydroisoquinoline analogue of safinamide. Structure-affinity relationships and docking simulations pointed out strong negative steric effects of alpha-aminoamide side chains and para substituents of the benzyloxy groups and favorable hydrophobic interactions of meta substituents. The significantly diverse MAO-B affinities of a number of R and S alpha-aminoamide enantiomers, including the two rigid analogues (21) of safinamide, indicated likely enantioselective interactions at the enzymatic binding sites.
authors.affiliation: Dipartimento Farmaco-Chimico, University of Bari, Via Orabona 4, I-70125 Bari, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Leonetti
authors.forename: Carmelida
authors.initials: C
authors.lastname: Capaldi
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pisani
authors.forename: Orazio
authors.initials: O
authors.lastname: Nicolotti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Muncipinto
authors.forename: Angela
authors.initials: A
authors.lastname: Stefanachi
authors.forename: Saverio
authors.initials: S
authors.lastname: Cellamare
authors.forename: Carla
authors.initials: C
authors.lastname: Caccia
authors.forename: Angelo
authors.initials: A
authors.lastname: Carotti
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D008958:Models, Molecular; D008996:Monoamine Oxidase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D044005:Tetrahydroisoquinolines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology