Cirrhosinones A-H, 24-hydroxy cevanine-type alkaloids from Fritillaria cirrhosa

Eight undescribed isosteroidal alkaloids cirrhosinones A-H (1–8), along with six known isosteroidal alkaloids (9–14), were isolated from the bulbs of Fritillaria cirrhosa D. Don. Their structures were determined by HRESIMS and 2D NMR analysis, and their absolute configurations were established by X-ray analysis. Compounds 1–8 possessed a typical cevanine-type alkaloid skeleton with a hydroxyl group rarely substituted at C-24 and compounds 4–8 possessed rare 7α or 7β-hydroxyl groups. This was the first report of both C-7 and C-24 hydroxyl groups substituted cevanine-type alkaloids. In addition, an approach for distinguishing D/E cis and trans conformations of cevanine-type alkaloids by 1H NMR data was developed. Moreover, the correlations between the relative configurations of 3-OH, 7-OH, 22-C, 24-OH, and 25-Me and the 1H NMR and 13C NMR data were also summarized. Compounds 1–9 exhibited moderate NO inhibitory activities in LPS-stimulated BV-2 cells at the concentration of 40 μM. The acetylcholinesterase inhibitory activities of compounds 1–7 and 9–10 were also evaluated and none of them showed acetylcholinesterase inhibitory activities at the concentrations of 20–80 μM.