Nitrogenous sesquiterpenes from the Thai marine sponge Halichondria sp.

Five nitrogenous sesquiterpenes having an isonitrile [(−)-axisonitrile-3], a formamide [(+)-axamide-3, axamide-2 and (3S^*,5R^*,6R^*,9R^*)-3-formamido-1(10)-cadinene], and an amine [(−)-halichamine] functionality were isolated from the Thai marine sponge Halichondria sp., together with two steroids, ergosterol and ergosterol peroxide. (−)-Axisonitrile-3 was isolated from the natural source for the first time, while (+)-axamide-3 and (−)-halichamine were new metabolites. The structures of these compounds were elucidated on the basis of their spectroscopic data and by chemical transformations. All sesquiterpenes were tested for their cytotoxic activity against six cancer cell lines (HeLa, HuCCA-1, A549, MOLT-3, HepG2, MDA-MB231). Only (−)-axisonitrile-3 showed strong activity to the HepG2 cell line with an IC₅₀ value of 1.3 μM.     

Halichonadins A-D, new sesquiterpenoids from a sponge Halichondria sp.

A new dimeric sesquiterpenoid with two eudesmane skeletons through a urea linkage, halichonadin A (1), as well as three new eudesmane sesquiterpenoids having a carbamate, an isonitrile, or an amino functionality, halichonadins B (2), C (3), and D (4), respectively, have been isolated from a marine sponge Halichondria sp., and the gross structures and relative stereochemistry of 1-4 were elucidated on the basis of spectral data and chemical means.     

Halichonadins G-J, new sesquiterpenoids from a sponge Halichondria sp.

Three new dimeric sesquiterpenoids, halichonadins G-I (1-3), and one new eudesmane sesquiterpenoid possessing a 1-phenethyl urea moiety, halichonadin J (4), were isolated from a marine sponge Halichondria sp. Halichonadins G (1) and H (2) are homo-dimers of eudesmane sesquiterpenoid, linked through a methyl 2-{1-(2-amino-2-oxoethyl)ureido}acetate fragment and a 2-hydroxymalonamide fragment, respectively, while halichonadin I (3) is a new hetero-dimer of eudesmane sesquiterpenoid linked through a urea fragment. The structures of 1-4 were elucidated on the basis of spectroscopic data.     

Cell differentiation inducers from a marine sponge Biemna sp.

Two pyridoacridines closely related to the known isocystodamine were isolated from the marine sponge Biemna sp. together with isocystodamine. Their structures were determined on the basis of spectroscopic data. They induce the erythroid differentiation of human leukemia K562 cells with an ED₅₀ value of 5 nM each.     

Bromine-containing alkaloids from the marine sponge Penares sp.

Two new unusual alkaloids were isolated from the sponge Penares sp., collected from Viet Nam waters (the South China Sea). The structures of these compounds were established by analysis of 1D, 2D NMR (¹H-¹H COSY, DEPT, HSQC, HMBC, H2BC, and NOE), and MS data. Compound 1 shows moderate cytotoxicity against the human tumor cells HL-60 and HeLa.     

Ircinamine B, bioactive alkaloid from marine sponge Dactylia sp.

Ircinamine B was isolated from the marine sponge Dactylia sp., which was collected at Cape Sada in Japan. Based on extensive spectral analysis, the structures of the isolated metabolites were established. This novel compound showed moderate activity against the murine leukemia cell line P388 (IC₅₀ 0.28 μg/mL).     

Cyclosmenospongine, a new sesquiterpenoid aminoquinone from an Australian marine sponge Spongia sp.

A new sesquiterpenoid aminoquinone, cyclosmenospongine (1), containing a dihydropyran ring, was isolated from an Australian marine sponge Spongia sp., along with the known metabolites, smenospongiarine, ilimaquinone and smenospongine. The structure of 1 was determined from spectroscopic data.     

Miyakosynes A-F, cytotoxic methyl branched acetylenes from a marine sponge Petrosia sp.

Cytototoxic linear acetylenes, miyakosynes A-F, were isolated from a marine sponge Petrosia sp. Their structures were elucidated by a combination of spectroscopic analyses and chemical methods. The absolute configuration of the secondary alcohols at each terminus was determined by the modified Mosher’s analysis. Miyakosynes show cytotoxicity against HeLa cells at submicromolar concentrations.     

Diplopuupehenone, a new unsymmetrical puupehenone-related dimer from the marine sponge Dysidea sp.

A new unsymmetrical puupehenone-related dimer, diplopuupehenone, comprising puupehenone and puupehenol segments, was isolated from the marine sponge Dysidea sp., along with the known metabolites, puupehenone and bispuupehenone. The structure of diplopuupehenone was established from spectroscopic data and by spectroscopic analysis of an acetoxy derivative. Diplopuupehenone showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with an IC₅₀ value of 8 μM.     

Untenolide A, a new polyketide from an Okinawan marine sponge Plakortis sp.

A new polyketide, untenolide A (1), has been isolated from an Okinawan marine sponge Plakortis species, and the structure was elucidated from spectroscopic data and X-ray analysis. Untenolide A (1) is a new polyketide possessing a fused-pentacyclic skeleton with two hexadecanyl chains.     

Jaspines A and B: two new cytotoxic sphingosine derivatives from the marine sponge Jaspis sp.

The ethanolic extract of the sponge Jaspis sp. collected in Vanuatu showed cytotoxicity against KB tumour cells (IC₉₅=10 μg/ml). A bioassay-guided fractionation led to the isolation of two new cytotoxic sphingosine derivatives, jaspine A and jaspine B. Structures were elucidated by spectroscopic methods, and absolute configuration by chemical derivatisation. The cytotoxicity of jaspine B hydrochloride was evaluated against the A549 lung tumour cell line (IC₅₀=3.4×10⁻⁷ M).     

Xestosaprol D and E from the Indonesian marine sponge Xestospongia sp.

Chemical investigation of an extract of the marine sponge Xestospongia yielded a suite of pentacyclic compounds, including two new xestosaprol derivatives. Xestosaprol D (1) and E (2) are regioisomers, whose structures were defined through analysis of spectroscopic data.     

Njaoamines G and H, two new cytotoxic polycyclic alkaloids and a tetrahydroquinolone from the marine sponge Neopetrosia sp.

Two new polycyclic alkaloids, njaoamines G (1) and H (2) and 1,2,3,4-tetrahydroquinolin-4-one (3) have been isolated from the sponge Neopetrosia sp. collected at Pemba Island, Tanzania. Compounds 1 and 2 are close in structure to njaoamines A-F. Compound 3, known synthetically, is a new natural compound. The structures and relative stereochemistries of compounds 1 and 2 were elucidated on the basis of spectroscopic data. Njaoamines G and H are potent brine shrimp toxins with LD₅₀ values of 0.17 μg/mL and 0.08 μg/mL for 1 and 2, respectively.     

Dactylospongiaquinone, a new meroterpenoid from the Australian marine sponge Dactylospongia n. sp.

Chemical investigation of the sponge Dactylospongia n. sp. collected near Mooloolaba, S.E. Queensland, has led to the isolation of dactylospongiaquinone (7) together with the known quinones (2-5). The new metabolite 7 possesses a different carbon framework from the known dictyoceratidaquinone (9) and is suggested to possess a cis-fused ring junction by extensive NOESY studies combined with molecular modelling calculations. The relative stereochemistry of the previously described cyclospongiaquinone-1 (3) and dehydrocyclospongiaquinone-1 (4) is also assigned on the basis of NOESY analyses. Full NMR spectroscopic assignments are provided for all compounds.     

Formamidobisabolene-based derivatives from a sponge Axinyssa sp.

Chemical examination of a Chinese sponge Axinyssa sp. resulted in the isolation of 12 new formamidobisabolene-based analogues named axinyssines A–L (1–12), along with a new natural product (13) and three known formamidobisabolenes (14–16). Their structures were determined on the basis of extensive NMR and mass spectroscopic analyses in association with ICD data, Mosher reaction and chemical conversion for the assignment of absolute configurations. All compounds were evaluated for antitumor and antimicrobial activities.     

Plakoridine C, a novel piperidine alkaloid from an Okinawan marine sponge Plakortis sp.

A new piperidine alkaloid plakoridine C (1) has been isolated from an Okinawan marine sponge Plakortis species, and the structure was elucidated from spectroscopic data. Plakoridine C (1) is a new alkaloid possessing a piperidine ring connected to a β-keto-γ-lactone through a double bond.     

Callipeltins F-I: new antifungal peptides from the marine sponge Latrunculia sp.

Four new antifungal peptides, callipeltins F-I, were isolated from the marine sponge Latrunculia sp., collected off Vanuatu islands. Their structures were elucidated by NMR and MS analysis. The new callipeltins exhibited anti Candida activity in the 10⁻⁴ M range.     

Cytotoxic polyacetylenes related to petroformyne-1 from the marine sponge Petrosia sp.

Four polyacetylenes related to petroformyne-1 were isolated from the marine sponge Petrosia sp. Their structures were determined on the basis of spectroscopic data and the modified Mosher analysis. They exhibit cytotoxic activity against P388 murine leukemia cells.     

Fascioquinols A-F: bioactive meroterpenes from a deep-water southern Australian marine sponge, Fasciospongia sp.

Chemical investigation of a southern Australian deep-water marine sponge, Fasciospongia sp., returned the new meroterpene sulfate fascioquinol A (1) together with a series of acid mediated hydrolysis/cyclization products, fascioquinols B (2), C (3) and D (4), and strongylophorine-22 (5). Additional co-metabolites include the new meroterpenes fascioquinol E (6) and fascioquinol F (8), together with the known sponge metabolite geranylgeranyl 1,4-hydroquinone (7). Structures were assigned to 1-8 on the basis of detailed spectroscopic analysis, chemical interconversion, mechanistic and biosynthetic considerations, and literature comparisons. The known 1,4-hydroquinone 7 was identified as the dominant cytotoxic principle in the Fasciospongia sp. extract, with selective inhibitory activity against gastric adenocarcinoma (AGS, IC₅₀ 8 μM) and neuroblastoma (SH-SY5Y, IC₅₀ 4 μM) cell lines. By contrast, while the fascioquinols displayed little or no inhibitory activity towards human cell lines, 1 and 2 displayed promising Gram-positive selective antibacterial activity towards Staphylococcus aureus (IC₅₀ 0.9-2.5 μM) and Bacillus subtilis (IC₅₀ 0.3-7.0 μM).     

Solid phase total synthesis of callipeltin E isolated from marine sponge Latrunculia sp.

Solid phase total synthesis of callipeltin E (1), truncated linear peptide isolated from marine sponge, Latrunculia sp. was achieved. Our strategy based on traditional Fmoc-SPPS was in common use TFA-treatment final deprotection to reach callipeltin E (1) contained acid-sensitive βMeOTyr.