3.5. Inhibition Assay of β-Amyloid Aggregation

According to an already reported 96-well plate procedure [25], the test compounds at 100 μM were incubated with Aβ₄₀ (30 μM) and 2% HFIP (1,1,1,3,3,3-hexafluoro-2-propanol), used as aggregation enhancer in PBS pH 7.4 for 2 h at room temperature. After the addition of ThT, the fluorescence was read at the 440/485 nm excitation/emission wavelength. Experiments were performed in triplicate, and the % inhibition values calculated as mean ± SD. For compounds showing more than 60% inhibition at a 100-μM concentration, typically, seven scalar concentrations (from 100 to 0.1 μM) of the test compound were evaluated, and IC₅₀ values were calculated by nonlinear regression of the response/concentration (log) curve by using Prism GraphPad software (ver. 5.01).