Rheum turkestanicum Janisch Root Extract Mitigates 6-OHDA-Induced Neuronal Toxicity Against Human Neuroblastoma SH-SY5Y Cells

Background and Objective: Rheum turkestanicum (R. turkestanicum) has been known to reduce inflammation and has antioxidant properties such as protective effect in neurons. This study aimed to determine the effects of R. turkestanicum on neuronal toxicity induced by the pro-parkinsonian neurotoxin 6-hydroxydopamine (6-OHDA) in neuroblastoma SH-SY5Y cells. Materials and Methods: MTT and DNA fragmentation by PI staining (sub-G1 peak) assays were used to determine cell viability and induction of apoptosis, respectively. Fluorimetry methods measured lipid peroxidation malondialdehyde (MDA) and reactive oxygen species (ROS) levels. The amount of glutathione (GSH) and the activity of superoxide dismutase (SOD) were measured by DTNB (5, 5′-Dithiobis(2-nitrobenzoic acid)  and pyrogallol respectively. Results: Pretreatment with 12.5 to 100 μg/mL of R. turkestanicum extract for 24 hours attenuated 6-OHDA (final concentration 42.5 μg/mL)-induced cytotoxicity. Also, the pretreatment of SH-SY5Y cells with R. turkestanicum inhibited 6-OHDA-stimulated apoptosis in a dose-dependent manner. Additionally, R. turkestanicum extract repressed 6-OHDA-induced oxidative stress as measured by the MDA, ROS, GSH, and SOD levels. Conclusion: The findings suggest that R. turkestanicum extract has neuroprotective activity on 6-OHDA-induced neuronal toxicity of neuroblastoma cells.