Phorbaketals A, B, and C, sesterterpenoids with a spiroketal of hydrobenzopyran moiety isolated from the marine sponge Phorbas sp.

Three new sesterterpenoids, phorbaketals A (1), B (2), and C (3) which have a spiroketal of the hydrobenzopyran moiety, were isolated from the Korean marine sponge Phorbas sp. Their complete structures were elucidated by spectral and chemical methods. They exhibited moderate cytotoxicity against human colorectal, hepatoma, and lung cancer cell lines. Furthermore, the cultivation of the bacterial fraction from the sponge afforded compound 1.

Phorbasins G--I: three new diterpenoids from the sponge Phorbas gukulensis.

Phorbasins G--I (1--3) were isolated from the sponge Phorbas gukulensis collected from Gagu-Do, Korea. The complete structure of the compounds was determined by NMR and MS spectroscopy, along with chemical reaction. Phorbasin G (1) was found to be a diterpene possessing a taurine residue.

Renierosides, cerebrosides from a marine sponge Haliclona (Reniera) sp.

Guided by the brine shrimp lethality assay, eight new cerebrosides (1-8) have been isolated from an extract of the marine sponge Haliclona (Reniera) sp. A novel feature of these cerebrosides was the presence of unprecedented amide-linked long-chain fatty acid moieties. The planar structures of the cerebrosides (1-8) were established by 1D and 2D NMR spectroscopic techniques, mass spectrometric analyses, and chemical degradation methods. The isolated compounds did not display cytotoxicity to a panel of five human solid tumor cell lines.

Identification of genes suitable for DNA barcoding of morphologically indistinguishable Korean Halichondriidae sponges.

The development of suitable genetic markers would be useful for defining species and delineating the species boundaries of morphologically indistinguishable sponges. In this study, genetic variation in the sequences of nuclear rDNA and the mitochondrial cytochrome c oxidase subunit 1 and 3 (CO1 and CO3) regions were compared in morphologically indistinguishable Korean Halichondriidae sponges in order to determine the most suitable species-specific molecular marker region. The maximal congeneric nucleotide divergences of Halichondriidae sponges in CO1 and CO3 are similar to those found among anthozoan cnidarians, but they are 2- to 8-fold lower than those found among genera of other triploblastic metazoans. Ribosomal internal transcribed spacer regions (ITS: ITS1 + ITS2) showed higher congeneric variation (17.28% in ITS1 and 10.29% in ITS2) than those of CO1 and CO3. Use of the guidelines for species thresholds suggested in the recent literature indicates that the mtDNA regions are not appropriate for use as species-specific DNA markers for the Halichondriidae sponges, whereas the rDNA ITS regions are suitable because ITS exhibits a low level of intraspecific variation and a relatively high level of interspecific variation. In addition, to test the reliability of the ITS regions for identifying Halichondriidae sponges by PCR, a species-specific multiplex PCR primer set was developed.

Cytotoxic oxylipins from a marine sponge Topsentia sp.

By a bioactivity-guided fractionation, seven new oxylipins, topsentolides A(1)-C(2) (1-7), were isolated from the MeOH extract of a marine sponge Topsentia sp. Detailed NMR and MS analyses established the planar structures of these structurally related oxylipins, which are proposed to be biosynthesized by lipoxygenation followed by cyclization of unsaturated fatty acids. Acetonide derivatives and MTPA esters were prepared to elucidate the stereochemistry of topsentolides B(1) (3), B(2) (4), and C(2) (7). All compounds were tested against a panel of five human solid tumor cell lines and displayed moderate cytotoxicity.

Cytotoxic bisindole alkaloids from a marine sponge Spongosorites sp.

Three new bisindole alkaloids of the hamacanthin class (1-3) and one new bisindole alkaloid of the topsentin class (6) were isolated along with known bisindole alkaloids (4, 5, 7-11) from the MeOH extract of a marine sponge Spongosorites sp. by bioactivity-guided fractionation. The planar structures were established on the basis of NMR, MS, and IR spectroscopic analyses. Configurations of compounds 1-4 were derived from 1H NMR data and optical rotation. Compounds 1, 4, 5, and 11 showed moderate to significant cytotoxicity against five human tumor cell lines, and compounds 1-5 showed weak antibacterial activity against clinically isolated methicillin-resistant strains.

Cytotoxic furanosesterterpenes from a marine sponge Psammocinia sp.

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.

New cytotoxic metabolites from a marine sponge Homaxinella sp.

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.

New cytotoxic sesterterpenoids and norsesterterpenoids from two sponges of the genus Sarcotragus.

New norsesterterpenoids (3 and 4), a sesterterpenoid (6), pyrroloterpenoids (7-10), and a stereoisomer of kurospongin (5) were isolated, along with known furanosesterterpenes (11-15), from two marine sponges of the genus Sarcotragus. The gross structures were established on the basis of NMR and MS analysis. The stereochemistry was defined by combined use of NMR and CD spectroscopy. The compounds were evaluated for cytotoxicity against five human tumor cell lines and were found to exhibit marginal to moderate activity.

Diversity of symbiotic archaeal communities in marine sponges from Korea.

A molecular analysis of archaeal communities in eight sponges collected along the coast of Cheju Island, Korea was conducted using terminal-restriction fragment length polymorphism (T-RFLP) in conjunction with sequencing analysis of 16S rDNA clones. The terminal-restriction fragment (T-RF) profiles showed that each sponge had a simple archaeal community represented by a single major peak of the same size except for one unidentified sponge (01CJ20). In order to identify the components of the community, 170 archaeal 16S rDNA clones were recovered from sponges and analyzed by RFLP typing. Sequences of 19 representative clones for all RFLP types found in each sponge were determined and phylogenetic analysis was carried out. Seventeen of these archaeal 16S rDNA clones showed a high similarity to marine group I, belonging to the crenarchaeotes. In the phylogenetic tree, 15 archaeal clones were grouped into five sponge-associated archaeal clusters. In the unidentified sponge sample (01CJ20), one major T-RF peak was represented by a single RFLP type (40 clones), which implied a specific relationship between the sponge and its symbiotic archaeal components.

New acetylenic acids from the marine sponge Stelletta species.

Four new acetylenic acids were isolated from the marine sponge Stelletta sp. by bioactivity-guided fractionation. The planar structures were established on the basis of NMR and MS analysis. The stereochemistry was defined by combined use of CD spectroscopy and a chiral anisotropic reagent, phenylglycine methyl ester (PGME). The compounds were evaluated for cytotoxicity against a small panel of five human tumor cell lines and exhibited marginal to moderate cytotoxicity.