Ki Woong Cho

New Bromotyrosine Metabolites from the Sponge Aplysinella rhax

Abstract Four new bromotyrosine metabolites (3–6) along with the previously described compounds psammaplin A (1) and bisaprasin (2) have been isolated from the sponge Aplysinella rhax collected from Guam, Palau, and Pohnpei. Based upon the results of extensive spectroscopic analysis and chemical reaction, the structures of psammaplins A1 (3) and A2 (4) have been determined to be a N,N-dimethylguanidium salt of psammaplin A sulfate and its bis-N,N-dimethylguanidium disulfate derivative, respectively. Aplysinellin A (5) possesses an additional bromotyrosine-derived C9 unit connected directly to the carbon framework of psammaplin A by a biphenylic linkage while aplysinellin B (6) is the corresponding cyclic enol ether. These compounds exhibited moderate cytotoxicity and inhibitory activities against farnesyl protein transferase and leucine aminopeptidase.

Sarcotragins A and B, new sesterterpenoid alkaloids from the sponge Sarcotragus sp.

Abstract Sarcotragins A ( 1 ) and B ( 2 ), two terpenoid alkaloids of an unusual structural class, have been isolated from the sponge Sarcotragus sp. collected from Jaeju Island, Korea. The structures of these compounds have been determined as linear trisnorsesterterpenes containing a phenethylamine lactam or the corresponding glycine lactam moiety by combined chemical and spectral methods.

Lipid content and composition of the Antarctic lamellibranch, Laternula elliptica (King & Broderip) (Anomalodesmata : Laternulidae), in King George Island during an austral summer

Abstract Total lipid content, lipid classes and fatty acid composition were studied in various tissues of the Antarctic clam Laternula elliptica in an early austral summer. A histological examination of the gonads revealed that most of the clams examined were spawning or ready to spawn. Lipid content was highest in gills (14.9% of tissue dry weight), followed by gonads (10.9%) and digestive glands (9.9%), and averaged 8.2% for the soft tissues. The overall lipid contents were relatively low compared to temperate bivalves at a similar reproductive stage. Lipid class composition in the total lipid of L. elliptica was quite similar to those of most marine bivalves at lower latitudes, being dominated by triacylglycerols (19.3–41.4% of total lipids) and phospholipids (18.9–28.3%) in most of the organs. Large amounts of triacylglycerol deposits in non-reproductive tissues, particularly in siphon and gill, indicate a potential role of lipid as maintenance energy reserve, although the low lipid contents suggest that lipid may not serve as an energy reserve for any food-limited periods. Fatty acid composition in L. elliptica was also typical of marine bivalves with predominance of 16:0 (26%) and 20:5n-3 (18%) acids. Total fatty acids from the soft tissues showed a moderate level of unsaturation (50.6%), and about 35% of the total fatty acids were polyunsaturated. These values were not significantly different from, or even lower than those of marine bivalves in warmer waters. However, the content of 20:5n-3 (18.2% of total fatty acids), which dominated n-3 polyunsaturated fatty acids, was similar to those reported for other marine bivalve species in temperate waters. The fatty acid composition of L. elliptica reflected dietary input of some microalgal species. The nanoflagellates Cryptomonas spp., which were reportedly rich in 16:0, 18:3n-3 and 20:5n-3, predominated in the water column during the present investigation.

Enzymatic Properties of an Extracellular Phospholipase C Purified from a Marine Streptomycete

A novel extracellular phospholipase C (PLC) was purified from a marine streptomycete. It had a molecular mass of 28 kDa as estimated by SDS-polyacrylamide gel electrophoresis. Its enzyme activity was optimal at pH 8.0 at 45 °C. The PLC hydrolyzed only phosphatidylcholine. Its activity was enhanced 300% by Na+ (200 mM), suggesting that the purified PLC is a typical marine-type enzyme.

New xenicane diterpenoids from the gorgonian Acalycigorgia inermis.

Eight diterpenes and norditerpenes including five new xenicane metabolites (4--8) have been isolated from the gorgonian Acalycigorgia inermis. The structures of these compounds have been determined by combined spectroscopic analysis. The new compounds exhibited significant cytotoxicity against a human leukemia cell-line.

New Farnesylhydroquinone Glycosides from the Gorgonian Euplexaura anastomosans

Abstract Euplexides F (3) and G (4), novel farnesylhydroquinone glycosides, have been isolated as minor constituents of the gorgonian Euplexaura anastomosans. The structures of these compounds have been determined by combined spectroscopic methods. These compounds exhibited moderate cytotoxicity and inhibitory activity against PLA2.

Growth Inhibition and Apoptosis with H31 Metabolites from Marine Bacillus SW31 in Head and Neck Cancer Cells

Objectives To determine whether a novel marine micro-organism with anticancer properties, H31, the metabolic product of Bacillus SW31, has anti-tumor effects on head and neck cancer, and potential for apoptotic-enhancing anti-cancer treatment of affected patients. Methods The cell viability and apoptosis assays were performed. Changes in the signal pathway related to apoptosis were investigated. Then, the therapeutic effects of H31 were explored in mouse xenograft model and drug toxicity of H31 was examined in zebrafish model. Results We identified the anticancer activity of H31, a novel metabolic product of Bacillus SW31. Bacillus SW31, a new marine micro-organism, has 70% homology with Bacillus firmus and contains potent cytotoxic bioactivity in head and neck cancer cells using MTT assay. Combined with c-JUN, p53, cytochrome C, and caspase-3, H31 induced apoptosis of KB cells, a head and neck cancer cell line. In a separate in vivo model, tumor growth in C3H/HeJ syngeneic mice was suppressed by H31. In addition, in a zebrafish model used for toxicity testing, a considerable dose of H31 did not result in embryo or neurotoxicity. Conclusion Growth inhibition and apoptosis were achieved both in vitro and in vivo in head and neck cancer cells after exposure to H31, a metabolite from the marine Bacillus species, without any significant toxicity effects even at considerable H31 dose concentrations.

Bioluminescent assay for sphingolipid ceramide N-deacylase using Vibrio harveyi dark mutant M-17

A new bioluminescent assay method for the activity of sphingolipid ceramide N-deacylase (SCDase: EC 3.5.1.69) as well as ceramidase (CDase: EC 3.5.1.23) was developed using bioluminescent marine bacteria. Enzymatically synthesized ceramide (N-myristoyl sphigosine, C14:0-18:l) and commercial SCDase were used in this demonstration, and myristic (tetradecanoic, C14:0) acid produced by the SCDase hydrolysis was quantified using Vibrio harveyi M-17, a dark mutant of V. harveyi. The in vivo light intensity of M-17 was stimulated up to thousands fold in the presence of myristic acid, was used for this assay. SCDase activity with as little as 10 μU and 5 nM of myristic acid production were detected in less than one min. The assay worked well for the determination of Km and chromatographic fraction assay.