Structural diversity of bioactive triterpenoids from Alangium salviifolium and their attenuation of acute lung injury through AKT/MAPK signaling.

Seventeen undescribed triterpenoids, comprising three structural types-protostanes (1-5), multifloranes (6-8), and oleanane analogs (10-18), along with eight known compounds (9, and 19-25), were isolated from the leaves of Alangium salviifolium, a plant of the genus Alangium (family Cornaceae). Their structures were elucidated through extensive NMR and HRESIMS analyses, and the absolute configurations of 1a, 6, 7, 10, and 11 were confirmed by X-ray diffraction. Interestingly, compound 1 underwent an intramolecular electrophilic addition to form derivative 1a spontaneously. Bioactivity evaluation demonstrated that compounds 11, 19, 20, 22, and 24 significantly inhibited nitric oxide (NO) production in LPS-induced RAW264.7 cells, with 19 showing the most potent activity. Further investigation confirmed that 19 alleviated LPS-induced inflammation in macrophages and lung injury in mice by modulating the AKT/MAPK pathway. These findings underscore the potential of A. salviifolium leaves as a source of anti-inflammatory agents.