Antioxidative activities of novel diphenylalkyl piperazine derivatives with high affinities for the dopamine transporter

A new series of diphenylalkyl piperazine derivatives with high affinities for the dopamine transporter (DAT), which were modified at both the diphenylalkyl moiety and the phenyl ring in the phenylamino moiety of 1-[4,4-bis(4-fluorophenyl)butyl]-4-[2-hydroxy-3-(phenylamino)propyl]piperazine 1, was evaluated for their inhibitory activities against auto-oxidative lipid peroxidation in canine brain homogenates. Some of these were approximately equivalent in activity to α-tocopherol as a potent antioxidant with IC50 values of low micromolar order, and the 4-hydroxyphenyl derivative 11 showed the most potent antioxidative activity with an IC50 value of 0.32 μM, exhibiting approximately 5-fold more potent activity than α-tocopherol. The structure–activity relationship (SAR) studies of the antioxidative activity of these derivatives are presented.