The mechanism of neuroprotective effect of Viola odorata against serum/glucose deprivation-induced PC12 cell death

Objective: Oxidative stress is associated with the pathogenesis of brain ischemia and other neurodegenerative disorders. Previous researches have shown the antioxidant activity of Viola odorata L. In this project, we studied neuro-protective and reactive oxygen species (ROS) scavenging activities of methanol  (MeOH) extract and other fractions isolated from V. odorata in PC12 cell line in serum/glucose deprivation  (SGD) condition. Materials and Methods: The PC12 neuronal cells were pretreated for 6 hr with MeOH extract and fractions of V. odorata (1 to 25 μg/ml) followed by 24 hr incubation under SGD condition. Cell viability was measured by Alamar Blue® assay. The level of ROS was calculated using DCFH-DA. Also, Bax/Bcl-2 protein ratio was analyzed by western blot assay. Results: SGD condition significantly decreased cells viability (p<0.001). Pretreatment with EtOAc (12.5 and 25 µg/ml), BuOH (12, 25, 50 µg/ml) and CH2Cl2 (1.5 µg/ml) fractions of V. odorata reduced SGD-induced cytotoxicity. MeOH extract could not increase the viability significantly. All four semi polar fractions (EtOAc, BuOH, CH2Cl2 and MeOH) decreased SGD-induced ROS production and changed Bax/Bcl-2 ratio. Conclusion: V. odorata showed promising effects against SGD condition; further mechanistic and clinical studies are warranted before application of V. odorata as a neuro-protective agent.