Title: Pharmacological evaluation of the anti-Parkinson activity of leaf extract of Senna auriculata: In vivo animal models and In vitro experimental studies

Background: Parkinson's disease (PD) is a chronic, progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra, resulting in motor dysfunction, oxidative stress, neuroinflammation, and impaired quality of life. Current pharmacological therapies primarily provide symptomatic relief and are associated with long-term adverse effects, highlighting the need for safer and more effective therapeutic alternatives. Medicinal plants rich in bioactive phytoconstituents have gained considerable attention because of their antioxidant and neuroprotective properties. Objective: The present study aimed to evaluate the anti-Parkinson potential of the leaf extract of Senna auriculata using in vivo experimental animal models and in vitro antioxidant and neuroprotective assays. Materials and Methods: Leaf extract of Senna auriculata was subjected to phytochemical evaluation followed by assessment of antioxidant activity using in vitro methods such as DPPH, nitric oxide, and hydrogen peroxide scavenging assays. Anti-Parkinson activity was investigated using established experimental animal models, including haloperidol-induced catalepsy and reserpine-induced Parkinsonism. Behavioral parameters including catalepsy, locomotor activity, muscle rigidity, and motor coordination were evaluated. Biochemical estimations such as superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), malondialdehyde (MDA), and dopamine levels were performed, along with histopathological examination of brain tissues to assess neuroprotection. Results: The leaf extract demonstrated significant antioxidant activity in vitro and improved behavioral performance in Parkinsonian animal models. Treatment significantly reduced catalepsy and motor deficits, restored endogenous antioxidant enzyme levels, decreased lipid peroxidation, preserved dopamine content, and improved neuronal architecture compared with disease control animals, indicating marked neuroprotective activity. Conclusion: The findings suggest that Senna auriculata leaf extract possesses promising anti-Parkinson potential through its antioxidant, anti-inflammatory, and neuroprotective mechanisms. The plant may serve as a potential natural therapeutic candidate for the management of Parkinson's disease. However, further molecular investigations and clinical studies are warranted to confirm its efficacy and safety.