The inhibitory effect of Astragalus flavone extract on hyperuricemia and its underlying molecular mechanism by targeting JNK/AP-1/NLRP3/IL-1β signaling pathway.

Background: Hyperuricemia (HUA) is a metabolic disease disturbing human health caused by the overproduction or underexcretion of uric acid (UA). Astragalus is the root of Astragalus membranaceus (Fisch.) Bunge, has notable regulatory effect on chronic nephritis, proteinuria and spontaneous sweating, suggesting it could be a potential anti-HUA agent. However, limited research has been conducted on its anti-HUA effect and mechanism.

Methods: The present study performed untargeted and plasma metabolomics of Astragalus extract to identify the main constituents that can be absorbed and exert effect in mice, and further investigated the underlying mechanism by enzyme activity assay, Western Blotting and molecular docking.

Results: The results showed that Astragalus flavone extract inhibited UA synthesis by binding to XOD to hinder substrate binding and inhibiting xanthine oxidase (XOD) protein expression, inhibited JNK/AP-1/NLRP3/IL-1β signaling pathway to alleviate prolonged HUA-induced inflammation and abnormal UA metabolism, and protected the kidney by reducing serum renal function index and improving renal tissue atrophy, fibrosis and tubular dilatation both in vitro and in vivo. Besides, glycitein and isoformononet were identified as the main flavones in Astragalus extract absorbed into the bloodstream of mice, isoformononetin was found to inhibit UA synthesis by direct binding to XOD, and glycitein was found to interact with c-Jun to facilitate UA excretion and inhibit inflammation.

Conclusion: This paper represents the pioneering investigation that firstly identifying two flavonoids of Astragalus extract that can be absorbed to fight against HUA, and elucidating their diverse molecular mechanism by targeting JNK/AP-1/NLRP3/IL-1β signaling pathway, UA metabolism and kidney protection.