Cytotoxic and Antimalarial Amaryllidaceae Alkaloids from the Bulbs of Lycoris radiata

Phytochemical investigation of the 80% ethanol extract of the bulbs of Lycoris radiata resulted in the isolation of five new Amaryllidaceae alkaloids: (+)-5,6-dehydrolycorine (1), (+)-3 alpha,6 beta-diacetyl-bulbispermine (2), (+)-3 alpha-hydroxy-6 beta-acetylbulbispermine (3), (+)-8,9-methylenedioxylhomolycorine-N-oxide (5), and 5,6-dihydro-5-methyl-2-hydroxyphenanthridine (7), together with two known compounds, (+)-3 alpha-methoxy-6 beta-acetylbulbispermine (4) and (+)-homolycorine-N-oxide (6). Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (H-1-H-1 COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. Alkaloid 1 showed potent cytotoxicity against astrocytoma and glioma cell lines (CCF-STTG1, CHG-5, SHG-44, and U251), as well as HL-60, SMMC-7721, and W480 cell lines with IC50 values of 9.4-11.6 mu M. Additonally, compound 1 exhibited antimalarial activity with IC50 values of 2.3 mu M for D-6 strain and 1.9 mu M for W-2 strain of Plasmodium falciparum.