Identification of a novel BACE1 inhibitor, timosaponin A-III, for treatment of Alzheimer's disease by a cell extraction and chemogenomics target knowledgebase-guided method

Abstract

BackgroundRhizoma Anemarrhenae (RA) has been conventionally used for treatment of Alzheimer's disease (AD) in Traditional Chinese Medicine, and thus, the active components from RA can be screened. PurposeThis research aimed to identify the active components of RA and their targets and further clarify the molecular mechanisms underlying its anti-AD activity. MethodsFirst, the potential active compounds from RA were screened by neurocyte extraction and micro-dialysis methods. Second, the potential targets were predicted by a chemogenomics target knowledgebase and further explored by surface plasmon resonance and enzyme activity assays. Third, the pharmacological effects were evaluated by employing APP/PS1 transgenic mice and SH-SY5Y-APP cells. ELISAs and Western blot analyses were used to evaluate the expression of key molecules in the amyloidogenic and NMDAR/ERK pathways. ResultsTimosaponin A-III (TA-III) was screened and identified as a potential active component for the anti-AD activity, and BACE1 was proven to be a potential high-affinity target. Enzyme kinetic analysis showed that TA-III had strong noncompetitive inhibitory activity against BACE1. The in vitro and in vivo assays indicated that TA-III had pharmacological effects through improving memory impairment, reducing Aβ aggregation via the amyloidogenic pathway and preventing neuronal impairment through downregulating the NMDAR/ERK signaling pathway. ConclusionTA-III targets BACE1 to reduce Aβ aggregation through down-regulating the NMDAR/ERK pathway for treating AD.