Epicatechin and Catechin in Cocoa Inhibit Amyloid β Protein Induced Apoptosis

To elucidate additional health benefits of cocoa phytochemicals on the neurotoxicity induced by amyloid β protein (Aβ), PC12 cells were treated with toxic peptide (Aβ25 - 35) and the effects of epicatechin, catechin, and cocoa were studied using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction, lactate dehydrogenase (LDH) release, and trypan blue exclusion methods. Significant increase in neuronal cell death was observed on PC12 cells treated with Aβ25 - 35 (25 μM), while epicatechin and catechin and their mixture prevented the Aβ-induced neuronal cell death. Aβ treatment also led to the increased membrane instability of PC12 cells. The membrane protective effects of the phenolics determined by LDH release and trypan blue exclusion assays demonstrated that epicatechin, catechin, and their mixture protect cellular membrane from Aβ-induced cytotoxicity. In these three different cell viability assays, the mixture of epicatechin and catechin showed the highest protective effect and synergistic activity. The present results showed that the major flavonoids of cocoa, epicatechin and catechin, protect PC12 cells from Aβ-induced neurotoxicity, and suggest that cocoa may have anti-neurodegenerative effect in addition to other known chemopreventive effects. Keywords: Alzheimer's disease; amyloid β protein; catechin; cocoa; epicatechin