Dithiothreitol (DTT) was adopted as a nucleophile to develop a new acid-catalyzed degradation method for grape seed proanthocyanidin extraction (GSPE). Backpropagation neural network and Box-Behnken design were employed and compared to establish the optimized degradation conditions. GSPE was reacted with DTT at a ratio of 1:1 under mild conditions with 0.14 M HCl at 40.8 °C for 60 min. Three monomeric proanthocyanidins and six novel flavan-3-ol-DTT conjugates consisting of three pairs of diastereomers were simultaneously obtained with a high yield (929 mg/g). All the degradation products showed protective effects against Aβ25-35-induced neurotoxicity in PC-12 cells and prevented Aβ25-35 aggregation based on the results from MTT and thioflavin T fluorescence assays, respectively. Detailed intermolecular interactions leading to the prevention of Aβ25-35 aggregation were elucidated using molecular docking. This work would provide new compounds from functional foods that can be explored for their neuroprotective potential.
Keywords: Amyloid fibrils; Back Propagation neural network; Degradation; Dithiothreitol; Grape seed proanthocyanidin extract; Molecular docking.
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