Tanshinones Inhibit Amyloid Aggregation by Amyloid-βPeptide Disaggregate Amyloid Fibrils and Protect Cultured Cells

摘要

The misfolding and aggregation of amyloid-β (Aβ) peptides into amyloid fibrils is regarded as one of the causative events in the pathogenesis of Alzheimer’s disease (AD). Tanshinones extracted from Chinese herb Danshen (Salvia Miltiorrhiza Bunge) were traditionally used as anti-inflammation and cerebrovascular drugs due to their antioxidation and antiacetylcholinesterase effects. A number of studies have suggested that tanshinones could protect neuronal cells. In this work, we examine the inhibitory activity of tanshinone I (TS1) and tanshinone IIA (TS2), the two major components in the Danshen herb, on the aggregation and toxicity of Aβ1–42 using atomic force microscopy (AFM), thioflavin-T (ThT) fluorescence assay, cell viability assay, and molecular dynamics (MD) simulations. AFM and ThT results show that both TS1 and TS2 exhibit different inhibitory abilities to prevent unseeded amyloid fibril formation and to disaggregate preformed amyloid fibrils, in which TS1 shows better inhibitory potency than TS2. Live/dead assay further confirms that introduction of a very small amount oftanshinones enables protection of cultured SH-SY5Y cells against Aβ-inducedcell toxicity. Comparative MD simulation results reveal a generaltanshinone binding mode to prevent Aβ peptide association, showingthat both TS1 and TS2 preferentially bind to a hydrophobic β-sheetgroove formed by the C-terminal residues of I31-M35 and M35-V39 andseveral aromatic residues. Meanwhile, the differences in binding distribution,residues, sites, population, and affinity between TS1-Aβ andTS2-Aβ systems also interpret different inhibitory effects onAβ aggregation as observed by in vitro experiments. More importantly,due to nonspecific binding mode of tanshinones, it is expected thattanshinones would have a general inhibitory efficacy of a wide rangeof amyloid peptides. These findings suggest that tanshinones, particularlyTS1 compound, offer promising lead compounds with dual protectiverole in anti-inflammation and antiaggregation for further developmentof Aβ inhibitors to prevent and disaggregate amyloid formation.