Abstract: AimTo compare the effects of salvianolic acid B (Sal B) and Ginkgo biloba extract EGb 761 on β-amyloid peptide (β-AP) fibril formation and cytotoxicity to PC12 cells. MethodsThe inhibitory effects of Sal B and EGb 761 on β-AP_1-40 fibril formation were determined by using fluorescence analysis with Thioflavin T (ThT) and electron microscopic image. β-AP_25-35 was aged by incubating at 37 ℃ for 7 d, then the protein was incubated with PC12 cells. The protective effects of Sal B and EGb 761 against cytotoxicity induced by aged β-AP_25-35 in PC12 cells were evaluated by MTT reduction assay and flow cytometric analysis. β-AP_25-35-induced accumulation of intracellular reactive oxygen species (ROS) was determined by fluorescence analysis. ResultsBoth Sal B and EGb 761 inhibited the formation of amyloid fibrils, protected PC12 cells from β-AP_25-35-induced cytotoxicity, and decreased ROS accumulation caused by β-AP_25-35. The effective doses of Sal B were far lower than those of EGb 761. ConclusionSal B was much more efficient than EGb 761 in inhibiting β-AP aggregation and in protecting PC12 cells from β-AP-induced cytotoxicity.