Abstract
Literary evidence depicts that aggregated β-amyloid (Aβ) leads to the pathogenesis of Alzheimer's disease (AD). Although many traditional Chinese medicines (TCMs) are effective in treating neurodegenerative diseases, there is no effective way for identifying active compounds from their complicated chemical compositions. Instead of using a traditional herbal separation method with low efficiency, we herein apply UHPLC-DAD-TOF/MS for the accurate identification of the active compounds that inhibit the fibrillation of Aβ (1-42), via an evaluation of the peak area of individual chemical components in chromatogram, after incubation with an Aβ peptide. Using the neuroprotective herbal plant Scutellaria baicalensis (SB) as a study model, the inhibitory effect on Aβ by its individual compounds, were validated using the thioflavin-T (ThT) fluorescence assay, biolayer interferometry analysis, dot immunoblotting and native gel electrophoresis after UHPLC-DAD-TOF/MS analysis. The viability of cells after Aβ (1-42) incubation was further evaluated using both the tetrazolium dye (MTT) assay and flow cytometry analysis. Thirteen major chemical components in SB were identified by UHPLC-DAD-TOF/MS after incubation with Aβ (1-42). The peak areas of two components from SB, baicalein and baicalin, were significantly reduced after incubation with Aβ (1-42), compared to compounds alone, without incubation with Aβ (1-42). Consistently, both compounds inhibited the formation of Aβ (1-42) fibrils and increased the viability of cells after Aβ (1-42) incubation. Based on the hypothesis that active chemical components have to possess binding affinity to Aβ (1-42) to inhibit its fibrillation, a new application using UHPLC-DAD-TOF/MS for accurate identification of inhibitors from herbal plants on Aβ (1-42) fibrillation was developed.