Synthesis, biological evaluation of 9-N-substituted berberine derivatives as multi-functional agents of antioxidant, inhibitors of acetylcholinesterase, butyrylcholinesterase and amyloid-β aggregation.

A series of 9-N-substituted berberine derivatives were synthesized and biologically evaluated as antioxidant and inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase and amyloid-β aggregation. Most of these compounds exhibited very good antioxidant activities, inhibitive activities of AChE and amyloid-β aggregation. Among them, compound 8d, (o-methylphenethyl)amino linked at the 9-position of berberine, was found to be a good antioxidant (with 4.05 μM of Trolox equivalents), potent inhibitor of AChE (an IC(50) value of 0.027 μM), and high active inhibitor of amyloid-β aggregation (an IC(50) value of 2.73 μM).