Enantiomeric 8-O-4 ' type neolignans from red raspberry as potential inhibitors of beta-amyloid aggregation

Red raspberry (Rubus idaeus L.) is an edible fruit-producing species belonging to the Rosaceae family. In our search for potential agents for treating Alzheimer's disease in this functional food, we decided to investigate the chemical constituents of red raspberry. Four pairs of enantiomeric 8-O-4'-type neolignans (1a/lb-4a/4b), including three new compounds (la/lb and 2a), were identified from the fruit of red raspberry. Their chemical structures were determined by spectroscopic data analyses, and all these isolated compounds were evaluated for their inhibition of self-induced A/beta aggregation, and 1b, 2a and 2b exhibited significant A/I aggregation inhibition ability. The results of the docking study of enantiomeric compounds la/lb and 3a/3b were consistent with the results of the thioflavin-T assay, and were used to further interpret the effects of a variety of stereochemical configurations on the A beta aggregation assay. Moreover, their neuroprotective activities were also evaluated. (C) 2017 Elsevier Ltd. All rights reserved.