Astragenol alleviates neuroinflammation and improves Parkinson's symptoms through amino acid metabolism pathway and inhibition of ferroptosis.

Background: Astragalus membranaceus (Fisch.) Bunge, as a tonifying medicine, is widely used in the traditional Chinese medicine treatment of Parkinson's disease (PD). We found Astragenol (AST) in the acid hydrolysis product of Astragalus membranaceus, which has anti-inflammatory and neuroprotective effects. However, the pharmacological effects and molecular mechanisms of AST in MPTP induced PD models have not been elucidated.

Objective: This study aims to verify whether AST can improve the symptoms of MPTP induced PD model and elucidate the molecular mechanisms underlying its pharmacological effects.

Methods: The pharmacological effects of AST on cell viability, cytotoxicity, behavior, and pathology were evaluated using PD in vitro (MPP+ induced SH-SY5Y cells) and in vivo models (MPTP induced mouse model). In addition, through metabolomics and transcriptomics, we investigate differential metabolites and differentially expressed genes, analyze potential signaling pathways, and conduct validation experiments around signaling pathways to explore molecular mechanisms.

Results: The results showed that AST can protect SH-SY5Y cells from the cytotoxic effects of MPP+. Pharmacodynamic experiments on PD in vivo have shown that AST can alleviate motor disorders caused by MPTP, reduce inflammatory factors in serum and brain tissue, and improve abnormal aggregation of α-synuclein in PD models. Furthermore, metabolomics analysis revealed that AST may exert a relieving effect on neuroinflammation and PD symptoms by regulating amino acid metabolism. Transcriptomic analysis revealed that the VDR gene is a potential gene for AST to exert pharmacological effects, and differential gene analysis suggests that the "Ferroptosis" signaling pathway may be a key pathway. Therefore, based on the "Ferroptosis" signaling pathway, we conducted validation analysis and the results showed that AST can intervene in the expression of iron transport related proteins to significantly alleviate the abnormal aggregation of iron ions in brain tissue, regulate the Nrf2/HO-1/GPX4 signaling pathway to inhibit the process of ferroptosis. In addition, we demonstrated at the cellular level that AST can reverse the increase in ROS levels induced by MPP+, and thus observed that AST improves the cellular morphological changes of ferroptosis.

Conclusions: In summary, this study explored the potential application of AST in neurodegenerative diseases and found that AST can intervene in the progression of neuroinflammation and alleviate symptoms of PD by inhibiting ferroptosis. This discovery provides scientific basis for the development of drugs or dietary supplements for the neuroprotective effect of AST, and lays data support for the comprehensive elucidation of the development and application of Astragalus membranaceus in the "medicinal food homology".