3-(Methyleneaminoxy)methylpiperidine derivatives as uptake inhibitors of biogenic amines in the brain synaptosomal fraction

A series of 3-(methyleneaminoxy)methylpiperidines (5a–h) and their corresponding N-methyl derivatives (6a–h) with a variety of substituents on the imino carbon were synthesized and tested for their potential antidepressant properties; their capacity to inhibit the re-uptake of biogenic amines (NA, 5-HT and DA) in rabbit brain synaptosomal fractions was also evaluated. The biological results obtained for the piperidine derivatives 5a–h and 6a–h and viloxazine 1, the reference drug, on the 3 re-uptake systems revealed that compounds 5 and 6 are generally able to inhibit biogenic amine uptake. The IC50 values for 5 and 6 were often lower than that of viloxazine 1, in particular for the serotonin- and/or dopamine-uptake systems. A higher activity was found for compounds substituted with at least one phenyl ring on the imino carbon with respect to completely aliphatic systems, and for N-unsubstituted compounds with respect to N-methyl-substituted compounds.