Abstract. The in vitro antimalarial activities against Plasmodium falciparum K1 of four extracts from the stembark
of Picrasma javanica Bl; ie water, methanol, chloroform and hexane extracts were studied using a modification
of the [3
H]hypoxanthine incorporation method. It was found that the hexane extract showed in vitro antimalarial
activity with IC50 of 3.3 μg/ml. The extract was further fractionated using quick column chromatography, resulting
in ten fractions. Fraction V was the most effective against P. falciparum K1 with IC50 of 4.4 μg/ml. Further
isolation of fraction V using a column chromatographic technique provided six fractions. According to 1
H- and 13C-NMR spectra, it could be concluded that the major compound in fraction V-3 was β-sitosterol. Unfortunately,
the antimalarial activity of β-sitosterol could not be determined because of its low solubility in DMSO. However,
fractions V-2 and V-4 still showed in vitro antimalarial activities with IC50 of 2.8 and 3.4 μg/ml, respectively. The
further fractionation of these two active fractions could lead to promising candidates as antimalarial agents.