Undescribed steroidal alkaloids from the bulbs of Fritillaria ussuriensis Maxim and their anti-inflammatory activities

In total, 16 undescribed steroidal alkaloids (1-16), along with nine known ones (17-25), were isolated from the bulbs of Fritillaria ussuriensis Maxim. Among the undescribed compounds mentioned, compounds 1-6, 8 bearing an 16fl-hydroxy substituent, as well as compounds 13 and 14 exhibited an unusual seven-membered skeleton. Their structures were established based on extensive spectroscopic analyses, including HRESIMS and NMR (1D and 2D), and comparison with the data reported in the literature. Furthermore, all the compounds were evaluated for their anti-inflammatory effect on the NO production of LPS-stimulated RAW264.7 cells. Compounds 1, 4, 11, 15, 22 and 24 could significantly inhibit NO production with IC50 values below 10 mu M.