Abstract

Natural products have been reported to exert positive impact on neurodegenerative diseases which arise as a result of neuronal loss associated with oxidative stress. Therefore, this study was conducted to evaluate the neuroprotective potential of ethanolic extract of Centella asiatica (CA) compared to that of tocotrienol rich fraction (TRF) using human neuroblastoma, SH-SY5Y cells. Cytotoxicity and neuroprotective effects of CA and TRF were measured by using 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) against BSO-induced neuron cell death. The rate of apoptotic cell death was measured via FITC Annexin V apoptosis flow cytometer. Presence of live and apoptotic cells were further confirmed with calcein-AM and propidium iodide fluorescence staining. Caspase-8 and -9 were measured to determine the mechanism of activation of the apoptotic pathway. Results showed that CA extract was toxic to neuron cell culture at ≥100 µg/ml. TRF (1 to 50 µg/ml), as positive control and CA (1 to 50 µg/ml) conferred significant protection against BSO-induced cell death. Post-treatment with CA also significantly reduced caspase-9 activity against BSO-induced cell death. In conclusion, this study shows that low concentration of ethanolic extract of CA is able to protect neuron cells from oxidative stress probably by inhibiting the activation of caspase-9 pathway but it can exert neurocytotoxic effect at high concentrations.

Key words: Centella asiatica L., antioxidant, neuroprotection, apoptosis, Caspase.