Protection of Differentiating Neuronal Cells from Amyloid β Peptide-induced Injury by Alkaline Extract of Leaves of Sasa senanensis Rehder

We have previously reported the protection of doxorubicin-induced keratinocyte toxicity by alkaline extract of the leaves of Sasa senanensis Rehder (SE). In order to extend the generality of the cell protective effect of SE, we investigated whether it also protects rat PC12 and human SH-SY5Y neuron model cells from amyloid β-peptide (Aβ)-induced injury. Viability of cells was determined by the MTT method. Cytotoxicity was evaluated by the concentration that reduces the cell viability by 50% (CC ). Protection from Aβ-induced cytotoxicity was evaluated by the concentration that reversed the Aβ-induced reduction of viability by 50% (EC ). The selectivity index (SI) of neuroprotective activity was defined as the ratio of EC to CC Aβ aggregation was assayed using Aβ ammonium hydroxide. SE showed hormetic growth stimulation at lower concentrations in both neuron precursors and differentiated cells. SE reproducibly inhibited Aβ-induced cytotoxicity against both undifferentiated and differentiated neuron cells. Both the extent of differentiation induction and viability depended on the cell density, suggesting the release of growth and differentiation stimulation substances into culture supernatant. Higher concentrations of SE partially reduced the Aβ aggregation. Hormetic growth stimulation and inhibition of aggregation may be involved in the neuroprotective activity of SE.