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Three new scalarane-based sesterterpenes, 1- 3, were isolated from a marine sponge of the genus Spongia, and their chemical structures were elucidated by analysis of HRMS and 2-D NMR spectra. The isolated compounds 1 and 3 showed inhibition against the farnesoid X-activated receptor (FXR) with IC50 values of 2.4 and 24 microM, respectively. In particular, compound 3 directly inhibited the interaction between FXR and a coactivator peptide (SRC-1) as determined by surface plasmon resonance (SPR) spectroscopy.

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.

One isoprenoid, tuberatolide A (1), meroterpenoids tuberatolide B (2) and 2'-epi-tuberatolide B (3), and the known meroterpenoids yezoquinolide (4), (R)-sargachromenol (5), and (S)-sargachromenol (6) were isolated from the Korean marine tunicate Botryllus tuberatus. The structures of these compounds were elucidated by NMR, MS, and CD spectroscopic analyses. These terpenoids antagonized the chenodeoxycholic acid (CDCA)-activated human farnesoid X receptor (hFXR) in a cell-based co-transfection assay with IC(50) values as low as 1.5 μM without significant effect on steroid receptors. Furthermore, they released the co-activator peptide from the CDCA-bound hFXR ligand binding domain in cell-free surface plasmon resonance experiments.

Two unprecedented phosphorus-containing iodinated polyacetylenes, phosphoiodyns A and B (1-2), were isolated from a Korean marine sponge Placospongia sp. Their structures were elucidated by spectroscopic data analysis. Phosphoiodyn A exhibited potent agonistic activity on human peroxisome proliferator-activated receptor delta (hPPARδ) with an EC(50) of 23.7 nM.

A chemical investigation of a Korean marine sponge, Phorbas sp., yielded unprecedented sesterterpenoids phorone A (1) and isophorbasone A (2) along with ansellone B (3) and phorbasone A acetate (4). Their complete structures were elucidated by the combination of spectroscopic data and chemical manipulation. Phorone A (1) and isophorbasone A (2) have the new "phorane"(5) and "isophorbasane"(6) sesterterpenoid carbon skeletons, respectively. Ansellone B (3) and phorbasone A acetate (4) exhibited potent inhibitory activity on nitric oxide production in RAW 264.7 LPS-activated mouse macrophage cells with IC(50) values of 4.5 and 2.8 μM, respectively.

Six seongsanamides were isolated from the culture broth of Bacillus safensis KCTC 12796BP, and their structures were elucidated by spectroscopic data analysis combined with Marfey's method, electronic circular dichroism calculations, and biosynthetic gene cluster analysis. Compounds 1−4 were bicyclic peptides with isodityrosine residues; 5 and 6 were monocyclic peptides. Only the bicyclic seongsanamides inhibited degranulation and LTC 4 /PGD 2 generation in IgE/Ag-stimulated bone marrow-derived mast cells. Oral administration of 1 suppressed mast cell-dependent passive cutaneous anaphylaxis reaction.

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