Activity against Plasmodium falciparum of Lactones Isolated from the Endophytic Fungus Xylaria sp.

Three lactones were isolated from the culture medium of the endophytic fungus Xylaria sp. Grev. (Xylariaceae). The major compound, which showed weak activity (13 mu g/mL) against a chloroquine-resistant strain of Plasmodium falciparum, was identified as (+)-phomalactone (1). The others were 6-(1-propenyl)-3,4,5,6-tetrahydro-5-hydroxy-4H-pyran-2- one (2) and 5-hydroxymellein (3). Compounds 1 and 2 are reported for the first time as constituents of Xylaria. Also, this is the first report of the activity of the compounds 1-3 against a chloroquine-resistant Plasmodium falciparum strain.