Evaluation of Neuroprotective Effect of Althaea Officinalis Flower Aqueous and Methanolic Extracts against H2O2-Induced Oxidative Stress in PC12 Cells

Objective: This study was conducted to evaluate the possible antioxidant activity and neuroprotective effects of aqueous and methanolic extracts of Althaea officinalis flowers against H2O2-induced oxidative stress in PC12 cells. Material and Methods: The antioxidant potential of extracts was evaluated by radical scavenging activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. For cytoprotective activity, the cells were pretreated with different concentrations (12.5, 25, 50, 100, 200 and 400 µg/ml) of the extracts for 24h and then incubated with H2O2 (480 μM) for 3 h. In co-treatment protocol, cells were simultaneously treated with H2O2 (480 μM) and the same concentrations of extracts, used in pretreatment protocol. Percentage of viability was measured using MTT assay. Results: The aqueous and methanolic extracts did not show strong DPPH radical scavenging activity (IC50 value of 128 and 255 μg/ml respectively) in comparison with ascorbic acid (IC50 value of 6.1 μg/ml). The cytoprtection study revealed that neither the methanolic, nor the aqueous extracts at tested concentrations could protect the cells against H2O2-induced cytotoxicity compared to H2O2 alone, in either co-treatment or pre-treatment experiments. Conclusion: Despite reporting the antioxidant activity of A. officinalis L. flowers, it seems that such a negligible cytoprotective activity may be related to some other factors. On the other hand, the presence of moderate antioxidant activity does not guarantee the protective activity against oxidative stress.