Two new alkaloids from the bulbs of Lycoris sprengeri.

Two new alkaloids, lycosprenine (1) and 2α-methoxy-6-O-methyllycorenine (2), along with 22 known alkaloids (3-23b), were isolated from the bulb of Lycoris sprengeri. Their structures were elucidated on the basis of spectral analysis and by comparison of the spectroscopic data with those of known compounds. Selected compounds (1-3 and 6-9) were tested for their neuroprotective activities against H2O2-, CoCl2- and Aβ25-35-induced SH-SY5Y cell injury, most of which exhibited neuroprotective effects of different degrees.