Apple Procyanidins Suppress Amyloid beta-Protein Aggregation

Procyanidins (PCs) are major components of the apple polyphenols (APs). We previously reported that treatment with PC extended the mean lifespan of Caenorhabditis elegans (Sunagawa et al., 2011). In order to estimate the neuroprotective effects of PC, we investigated the antiaggregative activity of PC on amyloid beta-protein (A beta) aggregation, which is a pathological hallmark of Alzheimer's disease. We herein report that PC significantly suppressed A beta 42 aggregation and dissociated A beta 42 aggregates in a dose-dependent manner, indicating that PC is a potent suppressor of A beta aggregation. Furthermore, PC significantly inhibited A beta 42 neurotoxicity and stimulated proliferation in PC-12 cells. These results suggested that the PC and AP acted as neuroprotective factors against toxic A beta aggregates.