Dongyup Hahn

Phosphoiodyns A and B, Unique Phosphorus-Containing Iodinated Polyacetylenes from a Korean Sponge Placospongia sp.

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.

Bioactive sesterterpenoids from a Korean sponge Monanchora sp.

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 Moshers 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.

Acredinones A and B, Voltage-Dependent Potassium Channel Inhibitors from the Sponge-Derived Fungus Acremonium sp. F9A015

Two new benzophenones, acredinones A (1) and B (2), were isolated from a marine-sponge-associated Acremonium sp. fungus. Their chemical structures were elucidated on the interpretation of spectroscopic data. The structure of 1 was confirmed by palladium-catalyzed hydrogenation, followed by spectroscopic data analysis. Acredinones A (1) and B (2) inhibited the outward K(+) currents of the insulin secreting cell line INS-1 with IC50 values of 0.59 and 1.0 μM, respectively.

Monanchosterols A and B, Bioactive Bicyclo[4.3.1]steroids from a Korean Sponge Monanchora sp.

Chemical investigation of a Korean marine sponge, Monanchora sp., led to the isolation of three new steroids (1-3). Compounds 1 and 2, designated as monanchosterols A and B, respectively, represent the first examples of steroids possessing the bicyclo[4.3.1] A/B ring system from a natural source. Compounds 1-3 were investigated for their anti-inflammatory activity by evaluating their inhibitory effects on the mRNA expression of IL-6, TNF-α, and COX-2 in the LPS-stimulated murine RAW264.7 macrophage cells. Compounds 2 and 3 exhibited significant inhibitory effects on the mRNA expression of IL-6 without notable cytotoxicity to the cells in a dose-dependent manner.

The Halicylindramides, Farnesoid X Receptor Antagonizing Depsipeptides from a Petrosia sp. Marine Sponge Collected in Korea.

Three new structurally related depsipeptides, halicylindramides F-H (1-3), and two known halicylindramides were isolated from a Petrosia sp. marine sponge collected off the shore of Youngdeok-Gun, East Sea, Republic of Korea. Their planar structures were elucidated by extensive spectroscopic data analyses including 1D and 2D NMR data as well as MS data. The absolute configurations of halicylindramides F-H (1-3) were determined by Marfeys method in combination with Edman degradation. The absolute configurations at C-4 of the dioxyindolyl alanine (Dioia) residues of halicylindramides G (2) and H (3) were determined as 4S and 4R, respectively, based on ECD spectroscopy. The C-2 configurations of Dioia in 2 and 3 were speculated to both be 2R based on the shared biogenesis of the halicylindramides. Halicylindramides F (1), A (4), and C (5) showed human farnesoid X receptor (hFXR) antagonistic activities, but did not bind directly to hFXR.

Fluvirucin B6, a new macrolactam isolated from a marine-derived actinomycete of the genus Nocardiopsis

A new 14-membered macrolactam natural product, fluvirucin B6 (1), was isolated from a marine-derived actinomycete, Nocardiopsis sp. CNQ-115, via HPLC-UV guided isolation. The chemical structure of 1 was elucidated by 1D and 2D NMR spectroscopic data analysis. Compound 1 showed a weak activity against Gram-positive bacteria, whereas it was inactive against Gram-negative bacteria.

Antartin, a Cytotoxic Zizaane-Type Sesquiterpenoid from a Streptomyces sp. Isolated from an Antarctic Marine Sediment

Antartin (1), a new zizaane-type sesquiterpene, was isolated from Streptomyces sp. SCO736. The chemical structure of 1 was assigned from the interpretation of 1D and 2D NMR in addition to mass spectrometric data. The relative stereochemistry of 1 was determined by analysis of NOE data, while the absolute stereochemistry was decided based on a comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Antartin (1) showed cytotoxicity against A549, H1299, and U87 cancer cell lines by causing cell cycle arrest at the G1 phase.

Enantioselective Synthesis of a Novel Thiazoline Core as a Potent Peroxisome Proliferator-Activated Receptor δ Agonist

The convergent and enantioselective synthesis of a highly potent human peroxisome proliferator-activated receptor delta agonist is presented. More specifically, the thiazoline structure, which constitutes the biosynthetically distinctive core structure of pulicatin (a secondary metabolite of symbiotic bacteria), was synthesized from a commercially available and inexpensive chiral pool of l-threonine.

Identification of Antiangiogenic Potential and Cellular Mechanisms of Napyradiomycin A1 Isolated from the Marine-Derived Streptomyces sp. YP127

Angiogenesis is the process of new blood vessel formation. Excessive angiogenesis is a critical factor in the progression of cancer, macular degeneration, and other chronic inflammatory diseases. When investigating the effects of crude extracts of cultured marine microorganisms, an extract of the cultured Streptomyces sp. YP127 strain was found to inhibit human umbilical vein endothelial cell (HUVEC) tube formation. Bioassay-guided fractionation and spectroscopic data analyses led to the identification of napyradiomycin A1 (1) as an antiangiogenic component of the extract. Compound 1 inhibited HUVEC tube formation in a concentration-dependent manner. It inhibited endothelial cell proliferation but did not affect human dermal fibroblast proliferation. Compound 1 also suppressed migration and invasion of vascular endothelial cells. In addition, compound 1 suppressed vascular endothelial cadherin expression and increased the permeability of the endothelial cell membrane. These results suggested that compound 1 modulates cell permeability and inhibits the angiogenesis of endothelial cells.