Molecular hybridization of 4-azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecane-3-ol with sigma (σ) receptor ligands modulates off-target activity and subtype selectivity.

A series of N-substituted 4-azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecan-3-ols incorporating the respective arylalkyl subunits from several known sigma (σ) receptor ligands were synthesized and evaluated for their affinity against σ receptors and dopamine receptors. The hybrid trishomocubane-derived ligands (4-6) showed good selectivity for σ(1) and σ(2) receptors over multiple dopamine receptors. The molecular hybrid obtained from haloperidol and 4-azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecan-3-ol (4, σ(1)K(i)=27 nM, σ(2)K(i)=55 nM) showed reduced affinity for D(1)-D(5) dopamine receptors when compared to haloperidol itself. The compound with the greatest σ(1) affinity in the series, benzamide 4 (σ(1)K(i)=7.6 nM, σ(2)K(i)=225 nM) showed a complete reversal of the subtype selectivity displayed by the highly σ(2) selective parent benzamide, RHM-2 (3, σ(1)K(i)=10412 nM, σ(2)K(i)=13.3 nM).
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