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

Two new triterpenoid saponins named astralanosaponins M and N (<b>1-2</b>), including a rare 20<i>S</i>, 24<i>S</i> cycloartane-type triterpenoid and three known compounds (<b>3-5</b>) were isolated from <i>Astragalus membranaceus</i> 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 <b>1</b>, <b>2</b> and <b>5</b> significantly suppressed LPS-induced NO production with IC₅₀ values ranging from 8.23 to 35.95 μM. The research results demonstrated that compound <b>2</b> exerts neuroprotective effects by inhibiting the NLRP3 inflammasome and suppressing inflammation in BV-2 cells.