Alkaloids from Fritillaria przewalskii Bulbs and Their Anti-Alzheimer's Disease Activities.

Three undescribed isosteroidal alkaloids, przewalskines A-C (1-3), as well as seven known alkaloids (4-10) were obtained from Fritillaria przewalskii bulbs. Their structures were deduced by extensive HRESIMS, 1D NMR, and 2D NMR analyses, and their bioactivities were evaluated involving the anti-inflammatory and inhibitory potencies on AChE, BChE, and Aβ aggregation. Compound 4 revealed the potent effect on inhibiting Aβ aggregation activity with IC 50 value of 33.1 μM, AChE activity with IC 50 value of 6.9 μM, and also showed NO release inhibitory acitivity with IC 50 value of 32.6 μM. These findings contribute new multi-.target anti-AD agents and embody the chemical diversity of F. przewalskii.