Relevance of benzyloxy group in 2-indolyl methylamines in the selective MAO-B inhibition.
1. Previous studies with indolyl derivatives as monoamine oxidase (MAO) inhibitors have shown the relevance of the indole structure for recognition by the active site of this enzyme. We now report a new series of molecules with structural features which determine the selectivity of MAO inhibition. 2. A benzyloxy group attached at position 5 of the indole ring is critical for this selective behaviour. Amongst all of these benzyloxy-indolyl methylamines, N-(2-propynyl)-2-(5-benzyloxyindol)methylamine FA-73 was the most potent MAO-B 'suicide' inhibitor studied. 3. The Ki values for MAO-A and MAO-B were 800+/-60 and 0.75+/-0.15 nM, respectively. These data represent a selectivity value of 1066 for MAO-B, being 48 times more selective than L-deprenyl (Ki values of 376+/-0.032 and 16.8+/-0.1 nM for MAO A and MAO-B, respectively). The IC50 values for dopamine uptake in striatal synaptosomal fractions from rats were 150+/-8 microM for FA-73 and 68 +/- 10 microM for L-deprenyl whereas in human caudate tissue the IC50 values were 0.36+/-0.015 microM for FA-73 and 0.10+/-0.007 microM for L-deprenyl. Moreover, mouse brain MAO-B activity was 90% ex vivo inhibited by both compounds 1 h after 4 mg kg(-1) administration, MAO-A activity was not affected. 4. These novel molecules should provide a better understanding of the active site of monoamine oxidase and could be the starting point for the design of further selective, non-amphetamine-like MAO-B inhibitors with therapeutic potential for the treatment of neurological disorders.
Pérez
V
V
Departament de Bioquímica i Biologia Molecular Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Marco
J L
JL
Fernández-Alvarez
E
E
Unzeta
M
M
D000818:Animals; D004298:Dopamine / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008930:Mitochondria, Liver / Q000201:enzymology; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship; D014363:Tryptamines / Q000494:pharmacology*
D008996:Monoamine Oxidase Inhibitors; D014363:Tryptamines; D004298:Dopamine