Neuroprotective Effect of Tephrosia purpurea Against Mitochondrial Dysfunction by Regulation of the Caspase3/9 and Pink1/Parkin Complexes

Abstract

Background: Tephrosia pupurea is a perennial shrub that has been widely incorporated in Indian traditional medicine for its anti-inflammatory and hepatoprotective effects. Recent studies have identified T. purpurea as a source of acetylcholine esterase inhibitors. Aim: In this study, we have established the potential of T. purpurea as a potential source of drugs against Parkinsonism using an oxidopamine (6-OHDA) model. Methods: Metabolomics profiling of T. purpurea extract (TPE) was obtained using the HR-LCMS method. Enzymatic activities of Catalase, Glutathione, Superoxide Dismutase and Malondialdehyde were measured in vitro. Reactive Oxygen Species generation capacity and the mitochondrial membrane potential were also determined. The zebrafish embryos were treated with oxidopamine along with varying concentrations of T. purpurea extract and the swimming pattern and total distance travelled was evaluated. The mRNA expression of mitophagy related genes were measured using RT-PCR studies. Results: The metabolite profile of T. purpurea identified the presence of various polyphenols such as Genistein, Esculetin, and Chrysin that have neuroprotective effects. 6-OHDA-induced PD causes an increase in oxidative stress, reactive oxygen species generation, and affects mitochondrial stability. There was a significant increase in the catalase, glutathione, and superoxide dismutase levels and a decrease in Malondialdehyde and Reactive Oxygen Species levels in cells treated with TPE when compared to 6-OHDA treated cells. We then treated zebrafish embryos with 6-OHDA along with varying concentrations of T. purpurea extract, and the mRNA expression and swimming pattern were evaluated. The embryos cotreated with TPE showed improved swim pattern similar to untreated embryos, whereas those treated with the positive control failed to do so. T. purpurea extract also significantly decreased the expressions of casp3, casp9, lrrk2, and increased pink1 and parkin expression. Conclusion: Our study identifies Tephrosia purpurea extract as a viable candidate against 6-OHDA induced-neurotoxicity, and further studies of its effect in models of neurodegenerative diseases are required.