The CH,CI, extract of the leaves of Annona purpurea L. (Annonaceae) showed strong brine shrimp toxicity and pronounced activity against larvae of the yellow-fever mosquito Aedes aegypti. Activity-directed fractionation of the extract by a combination of column chromatography on silica gel, gel filtration, and high-pressure liquid chromatography led to the isolation of acetogenins 1 4 as the main active principles. The structures of two novel acetogenins named purpureacin 1 (5) and purpureacin 2 (6) were elucidated by spectroscopic analysis (UV, Eland DCI-MS, EI-MS of Me$i derivatives, 'Hand I3C-NMR). The configuration of 5 and 6 was not established due to the limited sample amount. Compounds M i also showed antifungal activity against Candida albicans, and 5 was slightly active against Bacillus subtilis.
Introduction. -Annonapurpurea L. (Annonaceae) is a bushy tree native to Middle and South America. Its fruit is edible, and its wood is used for the manufacture of paper. Various parts of the tree are employed in traditional medicine: the fruit juice is a remedy for fever, chills, and jaundice, and a decoction of the inner bark is prescribed for cases of dysentry and edema. In Panama, the leafy branch tips are boiled with those of Aegyphila martinicensis, and the resulting decoction is drunk to clear up skin eruptions [l]. The powdered seeds of A.purpurea were reported to be insecticidal [2], and several cytotoxic alkaloids [3] were isolated from this plant prior to our own investigation.
During preliminary screening, the CH,Cl, extract of the leaves of A.purpurea exerted strong toxicity towards larvae of the crustacean Artemia salina (brine shrimp) and pronounced activity against larvae of the mosquito Aedes aegypti, vector of yellow fever. We report here on the activity-guided isolation and structure elucidation of the active constituents, four known and two new y-lactone acetogenins.
Results. -The air-dried leaves of A.purpurea collected in Panama were extracted successively with petroleum ether and CH,Cl,. The CH,Cl, extract was submitted to activity-guided fractionation using the brine shrimp toxicity assay [4] and Aedes aegypti mosquito larvae toxicity [5]. Compounds 1-6 were isolated by a combination of open column chromatography on silica gel, gel filtration on Sephadex LH-20, and low-pressure and semi-preparative high-pressure liquid chromatography (HPLC; see Exper. Part).
The structures of the known acetogenins 1 4 were confirmed by UV, MS, and [a],, measurements. Compounds 1 and 2 were identified as rolliniastatin 1 [6] and bullatacin [7], respectively. They belong to the family of the bi(tetrahydr0furan)-