Six new meroterpenoids (1-6), along with arenarol (7), a known rearranged drimane sesquiterpene hydroquinone, were isolated from a Dysidea sp. sponge collected from the Federated States of Micronesia. On the basis of the results of combined spectroscopic analysis, compound 1 was determined to be the cyclic ether derivative of 7, whereas 2 and 3 were assigned as the corresponding sesquiterpene quinones containing taurine-derived substituents. Compounds 4-6 possess a novel tetracyclic skeleton formed by a direct linkage between the quinone and sesquiterpene moieties. The configurations of these new compounds were assigned on the basis of combined NOESY and ECD analysis. These compounds exhibited cytotoxic and antimicrobial activities and weak inhibition against Na(+)/K(+)-ATPase.

A new peptide, gombamide A (1), was isolated from the marine sponge Clathria gombawuiensis, collected from Korean waters. On the basis of the results of combined spectroscopic analyses, the structure of this compound was determined to be a cyclic C-terminally modified thiohexapeptide containing the unusual amino acid residues para-hydroxystyrylamide (pHSA) and pyroglutamic acid (pyroGlu). The absolute configurations of all amino acid residues were determined to be l by advanced Marfey's analysis. The new compound exhibited weak cytotoxicity against A549 and K562 cell lines as well as moderate inhibitory activity against Na(+)/K(+)-ATPase.

Gombaspiroketals A-C (1-3), tetracyclic sesterterpenes of a novel skeletal class, were isolated from the Korean marine sponge Clathria gombawuiensis. On the basis of the combined spectroscopic analyses, the structures of these compounds were determined to be highly rearranged sesterterpene spiroketal methoxyacetals (1 and 2) and a corresponding hemiacetal (3). The relative and absolute configurations were assigned by NOESY analysis and ECD calculations, respectively. These compounds exhibited moderate cytotoxicities and antibacterial activities.

Three new terpene metabolites (1-3) were isolated from the marine sponge Clathria gombawuiensis collected from Korean waters. On the basis of the results of combined spectroscopic analyses, the structures of phorone B (1) and ansellone C (2) were determined to be the sesterterpenes of the phorone and ansellone classes, respectively, whereas the saponin gombaside A (3) was a nortriterpene sodium O-sulfonato-glucuronide of the rare 4,4,14-trimethylpregnane class. The absolute configuration of the glucuronate of 3 was assigned by an application of the phenylglycine methyl ester (PGME) method. The new compounds exhibited moderate cytotoxicity against A549 and K562 cell lines, and compound 3 showed antibacterial activity. The cytotoxicity of 1 may be related to the presence of a free phenolic -OH group, as the corresponding O-methoxy derivative 4 is inactive.

Six new polyoxygenated steroids (1-6) along with clathriol (7) were isolated from the Korean marine sponge Clathria gombawuiensis. Based upon the results of combined spectroscopic analyses, the structures of gombasterols A-F (1-6) were elucidated to be those of highly oxygenated steroids possessing a 3β,4α,6α,7β-tetrahydroxy or equivalent (7β-sodium O-sulfonato for 3) substitution pattern and a C-15 keto group as common structural motifs. The relative and absolute configurations of these steroids, including the rare 14β configuration of 1-4, were determined by a combination of NOESY, J-based analyses, the 2-methoxy-2-(trifluoromethyl)phenylacetic acid (MTPA) method, and X-ray crystallographic analysis. The absolute configuration of 7 was also assigned by these methods. These compounds moderately enhanced 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d-glucose (2-NBDG) uptake in differentiated 3T3-L1 adipocytes and phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in differentiated mouse C2C12 skeletal myoblasts.