Objectives: To investigate the neuroprotective efficacy of Valeriana wallichii DC rhizome extract against 1-methyl-4-phenlypyridinium (MPP+) and tunicamycin induced cell death.
Methods: The 50% methanolic extract of V. wallichii rhizome (VWE) was evaluated for free radical scavenging properties. Cell viability analysis and IC50 determination for VWE in SH-SY5Y neuroblastoma cell line was performed by MTT assay. The neuroprotective efficacy of VWE in SH-SY5Y cells against the damages induced by the neurotoxin, MPP+ and the endoplasmic reticulum stress inducer, tunicamycin was assessed by MTT assay and by morphological analysis with phase contrast microscope. MTT assay was performed using 3 different concentrations (0.1, 0.5 and 1 mg/mL) of VWE that were added at 0, 8 and 16 h post MPP+ and tunicamycin treatment. Results: VWE showed good free radical scavenging properties. From the cell viability analysis the IC50 value of VWE was calculated as 2.207 mg/mL in SH-SY5Y cells. In MPP+ treated cells 0.5mg and 1mg/mL concentrations of VWE brought significant improvement in cell viability at 0h, while at 8h and 16h post MPP+ treatment the effect was significant at 1mg/ml concentration. VWE exhibited significant protective effect in tunicamycin treated cells only at 0h but not at 8h and 16h post treatment. MPP+ and tunicamycin induced cell shrinkage and condensation were inhibited by treatment with 1mg/mL of VWE.
Conclusions: The present work is the first study that sheds light on the cytoprotective effect of Valeriana wallichii DC rhizome and provides lead for identification and isolation of novel drugs for various neurodegenerative diseases.