Protective Effects of Hemerocallis Fulva Extracts on Amyloid $\beta$-Protein-Induced Death in Neuronal Cells

아밀로이드 베타 단백질에 의해 유도된 신경세포 독성에 대한 원추리의 억제 효과 탐색

Objectives : The amyloid $\beta$-protein ($A\beta$) 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 $A{\beta}toxicity$. In this study, we have investigated the protective effects of water- and organic solvent-extracts of Hemerocallis fulva root fractions pre-extracted with methanol on $A\beta$-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. Methods : For this study, we used MTT reduction assay for detection of protective effects of water- and organic solvent-extracts of Hemerocallis fulva root fractions pre-extracted with methanol on $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells. We also used cell-based $\beta$-secretase assay system to investigate the inhibitory effect of water- and organic solvent-extracts of Hemerocallis fulva root on $\beta$-secretase activity. Results : We previously reported that methanol extracts of Hemerocallis fulva root strongly attenuated cytotoxicity induced by the three $A\beta$ fragments ($A{\beta}_{25-35},\;A{\beta}_{1-42}\;A{\beta}_{1-43}$) to both SK-N-MC and PC12 cells. In the present study, we found that butanol-, ethylacetate-, chloroform-, and water-extracts of Hemerocallis fulva root fractions pre-extracted with methanol had strong protective effects against $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells and inhibitory potency to $\beta$-secretase activity. Conclusion : These results suggest that butanol-, ethylacetate-, chloroform-, and water-extracts of Hemerocallis fulva root fractions pre-extracted with methanol may contain the protective component(s) against $A\beta$-induced cell death in PC12 cells as well as inhibitory component(s) to $\beta$-secretase activity.