New triterpenoid saponins from Astragalus membranaceus Bunge and their anti-neuroinflammatory activity

Two new triterpenoid saponins named astralanosaponins M and N (1-2), including a rare 20S, 24S cycloartane-type triterpenoid and three known compounds (3-5) were isolated from Astragalus membranaceus Bunge. Their chemical structures were clarified through spectroscopic data analytics, with their corresponding absolute configurations measured through ECD calculations. The anti-neuroinflammatory activity was assessed using LPS-stimulated BV-2 microglia. Compounds 1, 2 and 5 significantly suppressed LPS-induced NO production with IC₅₀ values ranging from 8.23 to 35.95 μM. The research results demonstrated that compound 2 exerts neuroprotective effects by inhibiting the NLRP3 inflammasome and suppressing inflammation in BV-2 cells.