The anti-dementia drug candidate, (−)-clausenamide, improves memory impairment through its multi-target effect

Multi-target drugs, such as the cocktail therapy used for treating AIDS, often show stronger efficacy than single-target drugs in treating complicated diseases. This review will focus on clausenamide (clau), a small molecule compound originally isolated from the traditional Chinese herbal medicine, Clausenalansium. The finding of four chiral centers in clau molecules predicted the presence of 16 clau enantiomers, including (−)-clau and (+)-clau. All of the predicted enantiomers have been successfully synthesized via innovative chemical approaches, and pharmacological studies have demonstrated (−)-clau as a eutomer and (+)-clau as a distomer in improving cognitive function in both normal physiological and pathological conditions. Mechanistically, the nootropic effect of (−)-clau is mediated by its multi-target actions, which include mild elevation of intracellular Ca2+ concentrations, modulation of the cholinergic system, regulation of synaptic plasticity, and activation of cellular and molecular signaling pathways involved in learning and memory. Furthermore, (−)-clau suppresses the pathogenesis of Alzheimer's disease by inhibiting multiple etiological processes: (1) beta amyloid protein-induced intracellular Ca2+ overload and apoptosis and (2) tau hyperphosphorylation and neurodegeneration. In conclusion, the nature of the multi-target actions of (−)-clau substantiates it as a promising chiral drug candidate for enhancing human cognition in normal conditions and treating memory impairment in neurodegenerative diseases.