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Chemical investigation of a Korean marine sponge, Monanchora sp., yielded nine new sesterterpenoids (1-9) along with phorbaketals A-C (10-12). The planar structures were established on the basis of NMR and MS analysis, and the absolute configurations of 1-9 were defined using the modified Mosher's method and CD spectroscopic data analysis. Compounds 1-8, designated as phorbaketals D-K, possess a spiroketal-modified benzopyran moiety such as phorbaketal A, and their structural variations are due to oxidation and/or reduction of the tricyclic core or the side chain. Compound 9, designated as phorbin A, has a monocyclic structure and is proposed to be a possible biogenetic precursor of the phorbaketals. Compounds 1-9 were evaluated for cytotoxicity against four human cancer cell lines (A498, ACHN, MIA-paca, and PANC-1), and a few of them were found to exhibit cytotoxic activity.

Three new (1-3) and seven known (4-10) cytotoxic furanosesterterpenes were isolated from a marine sponge Psammocinia sp. by bioactivity-guided fractionation. The structures were established on the basis of NMR and MS analyses. The geometry and absolute configuration were determined on the basis of optical rotation, NMR, and CD data. These compounds were evaluated for cytotoxicity against a small panel of five human tumor cell lines, and most of the compounds showed toxicity to SK-MEL-2. The mixture of compounds 7 and 8 displayed significant inhibition of DNA replication and moderate antioxidant profile.

Three new butenolides (1-3), a new cyclopentenone derivative (4), and a known alcohol (5) were isolated from a marine sponge Homaxinella sp. by bioactivity-guided fractionation. The planar structures were established on the basis of NMR and MS analyses. The stereochemistry of the butenolides and cyclopentenone derivative was defined on the basis of optical rotation and CD spectroscopy. The compounds were tested for cytotoxicity against a panel of five human solid tumor cell lines and displayed marginal to significant activity.

Two new acyclic furanoditerpene compounds, saurufuran A (1) and B (2), were obtained from the root of Saururus chinensis, and their structures were elucidated by means of 1D and 2D NMR spectroscopic analyses. Saurufuran A (1) is effective on the activation of peroxisome proliferator-activated receptor gamma (PPARgamma) with an EC(50) value of 16.7 microM; however, saurufuran B (2), with an EC(50) value of >100 microM, weakly activated the PPARgamma.

Five new (1-3, 5, and 7) and two known (4, 6) furanosesterterpene tetronic acids were isolated from the marine sponge Sarcotragus sp. by bioactivity-guided fractionation. These compounds showed cytotoxicity against a panel of five human tumor cell lines. The gross structures were established on the basis of NMR and MS analyses. The compounds showed interesting variations of geometry and absolute configuration.

Three new tetrahydrofuran-type sesquilignans, called saucerneol A, saucerneol B and saucerneol C were isolated from the underground parts of Saururus chinensis (Saururaceae), together with known lignans, di-O-methyltetrahydrofuriguaiacin B, machilin D and machilin D 4-methyl ether. Their structures were established from several spectral data.