In this investigation, a number of phenoxyindole derivatives were designed, synthesized, and tested for their neuroprotective ability on SK-N-SH cells against Aβ42-induced cell death and biologically specific activities involved in anti-Aβ aggregation, anti-AChE, and antioxidant effects. The proposed compounds, except compounds 9 and 10, could protect SK-N-SH cells at the IC50 of anti-Aβ aggregation with cell viability values ranging from 63.05% ± 2.70% to 87.90% ± 3.26%. Compounds 3, 5, and 8 demonstrated striking relationships between the %viability of SK-N-SH cells and IC50 values of anti-Aβ aggregation and antioxidants. No significant potency of all synthesized compounds against AChE was found. Among them, compound 5 showed the strongest anti-Aβ and antioxidant properties with IC50 values of 3.18 ± 0.87 and 28.18 ± 1.40 μM, respectively. The docking data on the monomeric Aβ peptide of compound 5 demonstrated good binding at regions involved in the aggregation process, and the structural feature made it possible to be a superior radical scavenger. The most effective neuroprotectant belonged to compound 8, with a cell viability value of 87.90% ± 3.26%. Its unique mechanisms for enhancing the protective impact may serve additional purposes since it demonstrated mild biological-specific effects. In silico prediction of CNS penetration shows strong passive penetration ability across the blood-brain barrier from blood vessels to the CNS for compound 8. In light of our findings, compounds 5 and 8 appeared as potentially intriguing lead compounds for new therapeutic approaches to Alzheimer's disease. More in vivo testing will be revealed in due course.
Keywords: Alzheimer’s disease; antiamyloid beta aggregation; antioxidant; indole-based scaffold; neuroprotective activity.