Synthesis and in vitro Evaluation of Novel Indole-Based Sigma Receptors Ligands

To investigate the molecular features involved in sigma (σ) receptors binding, a series of compounds based on indole scaffolds were synthesized and their chemical structures were confirmed by (1) H-NMR, IR, and elemental analysis. Their affinity toward σ(1) and σ(2) receptor subtypes was evaluated. 1-{[4-(2-phenylethyl)piperazin-1-yl]methyl}-3-methyl-1H-indole 3b had a high affinity to σ(1) receptors, while three compounds, 1-{3-[4-(substitutedphenyl)piperazin-1-yl]propyl}-1H-indole derivatives 4a-c had shown high affinity and selectivity for σ(2) receptors. Cytotoxicity of the compounds was demonstrated on cancer cell lines from liver (HUH7), breast (MCF7), and colon (HCT-116) cancer cell lines. Compound 1c (3-{[4-(3,4-dichlorobenzyl)piperazin-1-yl]methyl}-1H-indole) showed significant cell growth inhibitory activity on the selected cancer cell lines.