Novel 3-phenylcoumarin-lipoic acid conjugates as multi-functional agents for potential treatment of Alzheimer's disease

New series of triazole-containing 3-phenylcoumarin-lipoic acid conjugates were designed as multi-functional agents for treatment of Alzheimer's disease. The target compounds 4a-o were synthesized via the azide-alkyne cycloaddition reaction and their biological activities were primarily evaluated in terms of neuroprotection against H2O2-induced cell death in PC12 cells and AChE/BuChE inhibition. The promising compounds 4j and 4i containing four carbons spacer were selected for further biological evaluations. Based on the obtained results, the benzocoumarin derivative 4j with IC50 value of 7.3 mu M was the most potent AChE inhibitor and displayed good inhibition toward intracellular reactive oxygen species (ROS). This compound with antioxidant and metal chelating ability showed also protective effect on cell injury induced by A beta(1-42) in SH-SY5Y cells. Although the 8-methoxycoumarin analog 4i was slightly less active than 4j against AChE, but displayed higher protection ability against H2O2-induced cell death in PC12 and could significantly block A beta-aggregation. The results suggested that the prototype compounds 4i and 4j might be promising multi-functional agents for the further development of the disease-modifying treatments of Alzheimer's disease.