In vitro Aβ fibrillogenesis in the presence or absence of EGb761. (A) Thioflavin T fluorescence assay. Aβ (46 μM) was incubated in the absence (control) or presence of 100 μg/ml of EGb761 (EGb), or 29 μg/ml of bilobalide (BB) or ginkgolides A, B, C, and J (GA, GB, GC, and GJ, respectively) for 96 h at room temperature. The whole extract EGb761 was tested in four independent experiments, the difference was statistically significant: P = 0.0014 by the unpaired two-tailed t test. The individual components were only tested once, therefore no variability or statistical significance is given. (B) Electron microscopy. Aβ peptide was incubated overnight either alone (a) or with 100 μg/ml of EGb761 (b) and examined by electron microscopy. (Bar = 100 nm.) The results were qualitatively reproduced in three independent experiments. (C) Immunoblotting of Aβ species using the antibody 6E10. Lane 1, freshly prepared Aβ; lanes 2 and 3, Aβ incubated without or with EGb761 for 24 h, respectively; lanes 4 and 5, Aβ incubated without or with EGb761 for 8 days, respectively. Arrows indicate Aβ monomers (Aβ) or oligomers (nAβ).