GC-MS and NMR analysis of Phyllidiella pustulosa and one of its dietary sources, the sponge Phakellia carduus.

Gas-chromatographic and mass-spectrometric and NMR analyses of the lipophilic extract of the nudibranch Phyllidiella pustulosa and the sponge Phakellia carduus clearly showed that the sponge formed a major part of the nudibranchs diet. The analyses also indicated that the nudibranch accumulates some of the sponge metabolites in preference to others. The main components of the extracts were identified as the new natural product 10-isothiocyano-4-cadinene (1), axisonitrile-3 (2), and a number of other sesquiterpenes similar to 1 and 2. Also positively identified, in the extract of the sponge were the two sterols (3beta,22E)-ergosta-5,8,22-trien-3-ol (4) and (3beta,22E)-stigmasta-5,7,22-trien-3-ol (5), and in the nudibranch extract caryophyllene (3). The new natural product 10-isothiocyano-4-cadinene (1) was shown to have moderate antiplasmodial activity (IC(50) 1.5 microgram/ml towards Plasmodium falciparum clones K1, and NF54).