Abstract A series of tacrine–ebselen hybrids were synthesised and evaluated as possible multifunctional anti-Alzheimer's disease (AD) agents. Compound 6i, which is tacrine linked with 5, 6-dimethoxybenzo [d][1, 2] selenazol-3 (2H)-one by a six-carbon spacer, was the most potent acetylcholinesterase (AChE) and butylcholinesterase (BuChE) inhibitor, with IC 50 values of 2.55 and 2.80 nM, respectively. Furthermore, this compound demonstrated ...