Cryptotanshinone against vascular dementia through inhibition of Aβ aggregation and inflammatory responses in cerebrovascular endothelial cells

Abnormal aggregation of amyloid-β (Aβ) peptides and associated inflammation and apoptosis in cerebrovascular endothelial cells are prelude to inhibition of onset of vascular dementia (VaD). Although small molecules have been widely used to mitigate the cell damage induced by aggregated species of Aβ, its molecular mechanism based on anti-amyloid properties and corresponding mitigation of cytotoxicity against cerebrovascular endothelial cells have not been elucidated. Herein, we used cryptotanshinone as the major bioactive compound from the root of Salvia miltiorrhiza Bunge to effectively inhibit Aβ fibrillation and associated cytotoxicity. Thoflavin T (ThT) and 1-Anilino-8-naphthalene sulfonate (ANS) fluorescence, Congo red, and circular dichroism (CD) analyses indicted that cryptotanshinone potentially inhibit Aβ1-42 aggregation through elongation of nucleation phase, apparent decrease in the slope of the growth phase, and the final fluorescence intensity in a concentration-dependent manner. Also, cell viability, inflammation and capsae-3 assays showed that co-incubation of Aβ1-42 peptide with cryptotanshinone in the aggregation buffer not only mitigated their cytotoxicity, but also reduced the levels of TNF-α, IL-1β, IL-6 and caspase-3 activity in cerebrovascular endothelial cells induced by Aβ1-42. This study suggested that cryptotanshinone may show a great promise in the development of small molecule-based platforms for the treatment of VaD.