Allium roseumL. extract inhibits amyloid beta aggregation and toxicity involved in Alzheimer's disease

Allium roseumis an important medicinal and aromatic plant, specific to the North African flora and a rich source of important nutrients and bioactive molecules including flavonoids and organosulfur compounds whose biological activities and pharmacological properties are well known. In the present study, the inhibition of amyloid beta protein toxicity by the ethanolic extract of this plant is investigated for the first time. Preliminary biochemical analyses identified k AE mpferol and luteolin-7-o-glucoside as the more abundant phenolic compounds. The effects ofA.roseumextract (ARE) on aggregation and aggregate cytotoxicity of amyloid beta-42 (A beta(42)), whose brain aggregates are a hallmark of Alzheimer's disease, were investigated by biophysical (ThT assay, Dynamic light scattering and transmission electron microscopy) and cellular assays (cytotoxicity, aggregate immunolocalization, ROS measurement and intracellular Ca(2+)imaging). The biophysical data suggest that ARE affects the structure of the A beta(42)peptide, inhibits its polymerization, and interferes with the path of fibrillogenesis. The data with cultured cells shows that ARE reduces Ass(42)aggregate toxicity by inhibiting aggregate binding to the cell membrane and by decreasing both oxidative stress and intracellular Ca2+. Accordingly, ARE could act as a neuroprotective factor against A beta aggregate toxicity in Alzheimer's disease.