Antileishmanial cyclic peroxides from the Palauan sponge Plakortis aff. angulospiculatus

Abstract As part of a program to discover new drugs for the treatment of tropical diseases, we have isolated and identified six new metabolites from the Palauan sponge Plakortis aff. angulospiculatus . Two cyclic peroxides show strong in vitro antiproliferative effects on promastigotes of Leishmania mexicana , a flagellate protozoan that causes leishmaniasis. The structures of the cyclic peroxides 1, 2 and 5 and furans 3, 4 and 6 were elucidated by interpretation of spectroscopic data, molecular modelling, and chemical interconversions.