Synthesis and biological evaluation of pentacyclo[5.4.0.0 2,6.0 3,10.0 5,9]undecane derivatives as potential therapeutic agents in Parkinson's disease

Abstract

In previous studies, the polycyclic cage amine 8-benzylamino-8,11-oxapentacyclo[5.4.0.0 2,6.0 3,10.0 5,9]undecane (NGP1-01) and a number of its derivatives showed positive effects in neuroprotection studies with MPTP, in vivo. In view of these findings, we examined these compounds for their effects on [ 3H]dopamine ([ 3H]DA) release and uptake inhibition in murine striatal synaptosomes, as well as for inhibition of baboon liver monoamine oxidase (MAO) B. In order to assess specificity, initial experiments focused on compounds that blocked dopamine uptake without causing appreciable release (<40% at 100 μM) of the transmitter. NGP1-01 blocked the uptake of [ 3H]DA with an IC 50 of 57 μM, while another compound, 8-phenylethyl-8,11-oxapentacyclo[5.4.0.0 2,6.0 3,10.0 5,9]undecane, blocked uptake at an IC 50 value of 23 μM. These values were comparable to that of another polycyclic cage amine, amantadine (IC 50; 82 μ), that is used in parkinsonian therapy. Structure–activity relationships of this series of compounds support the importance of geometric and steric, rather than electronic effects, in determining biological activity. MAO-B inhibition for this group was weak, with less than 50% inhibition at 300 μM for any of the compounds in the series. The present study suggests that blockage of the dopamine transporter may underlie, at least in part, their neuroprotective effects against MPTP-induced parkinsonism. These compounds may be considered as potential lead compounds for Parkinson's Disease therapy.