Untargeted Metabolomic Profiling of Astragalus membranaceus Aqueous Extracts Fermented by Pediococcus acidilactici Using UHPLC-Orbitrap MS

Astragalus membranaceus (AM) is a traditional medicinal and edible herb whose bioactive constituents suffer from low bioavailability. This study employed untargeted metabolomics based on ultra-high-performance liquid chromatography coupled with Orbitrap mass spectrometry (UHPLC-Orbitrap MS) to investigate metabolic alterations in AM aqueous extracts fermented by Pediococcus acidilactici (P. acidilactici) for 48 h. Multivariate statistical and pathway enrichment analyses identified 659 significantly altered metabolites (350 upregulated and 309 downregulated), which were primarily associated with organic acids, flavonoids, amino acid derivatives, alkaloids, phenylpropanoids and polyphenols. Fermentation markedly activated pathways related to arginine metabolism, carbon metabolism, and nicotinate and nicotinamide metabolism, accompanied by a substantial accumulation of functional compounds such as lactate, phenyllactic acid, indolelactic acid, and nicotinamide adenine dinucleotide (NAD+). Overall, P. acidilactici fermentation induced extensive metabolic reprogramming of AM aqueous extracts, leading to the enrichment of multiple bioactive metabolites and the activation of key functional processes. These findings provide mechanistic insights into probiotic fermentation of medicinal and edible herbs and offer a scientific basis for the development of value-added fermented AM beverages with improved nutritional and functional properties.