Effect of beta-fluorophenethylamine analogs on monoamine oxidase substrate preference.

A novel potentiometric assay was employed to evaluate the effects of beta-fluorination of phenethylamine (PEA) on brain MAO substrate preference. Through the use of the substrate selective MAO inhibitors clorgyline (type A) and Deprenyl (type B), F-PEA and F2-PEA were found to be preferred substrates for MAO type B. Since various degrees of fluorination of the parent PEA molecule proportionally decrease the pKa values, as well as their substrate activity for MAO, it is suggested that the protonated form of PEA and its respective mono and difluoro analogs are the preferred substrate forms for catalysis by brain MAO.