Enhance Uric Acid-Lowering Activity of Astragalus membranaceus via Gut Microbiota Biotransformation: Correlation of Chemical Composition With Efficacy.

Hyperuricemia is a common metabolic disorder associated with gout, renal dysfunction, and cardiovascular complications. Although Astragalus membranaceus has long been used in traditional medicine, the influence of gut microbiota biotransformation on its potential urate-lowering activity remains unclear. In this study, ethanol and water extracts of Astragalus membranaceus were subjected to in vitro fecal microbiota biotransformation, and their xanthine oxidase (XO) inhibitory activities before and after biotransformation were compared. The transformed ethanol extract was further fractionated by solvent partitioning, and the resulting fractions were characterized by UPLC-MS/MS. The results showed that biotransformation altered the XO inhibitory activity of both extracts, with a more evident increase in the ethanol extract than in the water extract. Among the solvent fractions, the ethyl acetate fraction exhibited the strongest inhibitory activity. Chemical profiling tentatively characterized 62 compounds and revealed marked compositional changes after biotransformation, particularly a reduction in glycosidic constituents together with enrichment of corresponding aglycone-related compounds. These findings suggest that gut microbiota biotransformation may be an important factor influencing the potential urate-lowering activity of Astragalus membranaceus and provide a basis for further identification of its bioactive constituents.