The amyloid β-protein (Aβ) is the principal component of the senile plaques characteristic of Alzheimer's disease (AD) and elicits a toxic effect on neurons in vitro and in vivo. Many environmental factors including antioxidants and proteoglycans modify Aβ toxicity. In this study, we have investigated the effects of methanol-extracts of Liliaceae root on Aβ-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. For this study, we used three different Aβ fragments (Aβ_25-35, Aβ_1-42 Aβ_1-43) for the induction of cytotoxicities to PC12 cells. We previously measured cytotoxicities of the extracts of Liliaceae to both human neuronal SK-N-MC and PC12 cells. Fifteen out of the 19 Liliaceae extracts at 100μg/ml showed no cytotoxic effects to both SK-N-MC and PC12 cells. Three different Aβ fragments (Aβ_25-35, Aβ_1-42 Aβ_1-43) exhibited cytotoxicities to both SK-N-MC and PC12 cells, each possessing 1, 5, and 5μg/ml IC₅₀ values, respectively. Among the Liliaceae roots, methanol-extracts of Polygonatum falcatum, Ophiopogon japonicus, Liriope platyphylla, and Hemerocallis fulva strongly attenuated cytotoxicities induced by the three Aβ fragments. Especially methanol-extracts of Ophiopogon japonicus was the most effective in protecting PC12 cells from the Aβ_25-35-induced oxidative cell death. These results suggest that extracts of Liliaceae root may contain the protective component (s) against Aβ-induced cell death in PC12 cells. (Cancer Prev Res 10, 242-250, 2005)

Keywords: Amyloid β-protein, Liliaceae, Oxidative stress, PC12, Neuronal SK-N-MC