Objective: To explore the effects of azure B on metabolism of amyloid precursor protein (APP) and generation of amyloid-beta (Aβ) protein. Methods: Neuron-2a cells that stably expressed APP695 gene (N2a-APP695) was treated with azure B.Levels of APP

soluble APPα (sAPPα) and β-site APP cleaving enzyme 1 (BACE1) were measured by Western bolt. Aβ levels were measured by ELISA. The BACE1 enzyme inhibition was determined by using BACE1 activity assay kit. Data were analyzed by t test. Results: ①Azure B was not able to influence the cell viability of N2a-APP695 cells with final concentration of 5

10

15 and 20 μmol/L.②According to ELISA results

azure B was able to decrease levels of Aβ1-40 (P=0.002) and Aβ1-42 (P=0.036). ③Western blot demonstrated that azure B was able to reduce levels of full length APP (P=0.018) and sAPPα (P=0.006)

but not influence the protein level of BACE1 (P>0.05).④BACE1 activity assaying results showed that the activity of the BACE1 enzyme was significantly inhibited by azure B

with inhibition rate of 66.0% (P=0.000). Conclusion: Azure B inhibits the generation of Aβ by inhibiting the expression of APP and the activity of BACE1.