It is necessary to explore potent therapeutic agents via regulating gut microbiota and metabolism to combat Parkinson's disease(PD).Dioscin,a bioactive steroidal saponin,shows various activities.How-ever,its effects and mechanisms against PD are limited.In this study,dioscin dramatically alleviated neuroinflammation and oxidative stress,and restored the disorders of mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).16 S rDNA sequencing assay demonstrated that dioscin reversed MPTP-induced gut dysbiosis to decrease Firmicutes-to-Bacteroidetes ratio and the abundances of Enterococcus,Streptococcus,Bacteroides and Lactobacillus genera,which further inhibited bile salt hy-drolase(BSH)activity and blocked bile acid(BA)deconjugation.Fecal microbiome transplantation test showed that the anti-PD effect of dioscin was gut microbiota-dependent.In addition,non-targeted fecal metabolomics assays revealed many differential metabolites in adjusting steroid biosynthesis and pri-mary bile acid biosynthesis.Moreover,targeted bile acid metabolomics assay indicated that dioscin increased the levels of ursodeoxycholic acid,tauroursodeoxycholic acid,taurodeoxycholic acid and β-muricholic acid in feces and serum.In addition,ursodeoxycholic acid administration markedly improved the protective effects of dioscin against PD in mice.Mechanistic test indicated that dioscin significantly up-regulated the levels of takeda G protein-coupled receptor 5(TGR5),glucagon-like peptide-1 receptor(GLP-1R),GLP-1,superoxide dismutase(SOD),and down-regulated NADPH oxidases 2(NOX2)and nu-clear factor-kappaB(NF-κB)levels.Our data indicated that dioscin ameliorated PD phenotype by restoring gut dysbiosis and regulating bile acid-mediated oxidative stress and neuroinflammation via targeting GLP-1 signal in MPTP-induced PD mice,suggesting that the compound should be considered as a prebiotic agent to treat PD in the future.