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 IC₅₀ value of 33.1 μM, AChE activity with IC₅₀ value of 6.9 μM, and also showed NO release inhibitory acitivity with IC₅₀ value of 32.6 μM. These findings contribute new multi-.target anti-AD agents and embody the chemical diversity of F. przewalskii.