Selective inhibition of the "B form" of monoamine oxidase.

Deprenyl (phenyl-isopropyl-methyl-propinylamine) is a potent inhibitor of monoamine oxidase (MAO) and like the acetylenic type of inhibitors it induces irreversible inhibition of the enzyme. Its levorotatory isomer is a more potent inhibitor than the dextrorotatory one. Deprenyl elevates the concentration of 3H-noradrenaline (3H-NA) in the synaptosomal fraction of rat heart homogenate while pargyline, probably due to its releasing effect, decreases 3H-NA content in the same fraction. Deprenyl is a selective inhibitor of the "B form" of MAO, which preferentially oxidizes beta-phenylethylamine as substrate.