A new lycorine derivative LT1 (4) was isolated from the aerial part and bulbs of 
Lycoris traubii Hayward (Amaryllidaceae). Its structure including absolute 
configuration was established by spectroscopic analysis and semi-synthesis to be 
1-O-(3'S)-hydroxybutanoyllycorine. Some lycorine ester derivatives including LT1 
were examined for their inhibitory activity against Trypanosoma brucei brucei, 
the parasite associated with sleeping sickness, and against Plasmodium 
falciparum, the causative agent of malaria. Among them, 2-O-acetyllycorine (6) 
showed the most potent activity against parasitic T. b. brucei, and LT1 (4), 
1-O-(3'R)-hydroxybutanoyllycorine (8), 1,2-di-O-butanoyllycorine (11), and 
1-O-propanoyllycorine (12) showed significant activity against P. falciparum in 
an in vitro experiment.