Njaoamine I,a cytotoxic polycyclic alkaloid from the Haplosclerida sponge Haliclona (Reniera) sp.

A new cytotoxic polycyclic alkaloid containing a quinoline moiety, njaoamine I (1) has been isolated from the methanol extract of the sponge Haliclona (Reniera) sp. collected at Okuza Island, Tanzania. The structure of compound 1 was determined by 1D and 2D NMR and HRMS data analysis. Its relative configuration was elucidated by a NOESY experiment and confirmed by comparison of its NMR spectral data to those of njaoamines A–H. Moreover, njaoamine G (2) was also detected by LC/MS analysis of the methanol extract. Njaoamine I (1) displays cytotoxic activity against a panel of three human tumor cell lines in the micromolar range.     

Hyrtimomines,indole alkaloids from Okinawan marine sponges Hyrtios spp.

Six new indole alkaloids, hyrtimomines F–K (1–6), were isolated from Okinawan marine sponges Hyrtios spp. The structures of 1–6 were elucidated on the basis of spectroscopic analysis. Hyrtimomine F (1) is a structurally unique bisindole alkaloid possessing an α-keto-?-caprolactam ring, while hyrtimomine G (2) is a symmetrical bisindole alkaloid. Hyrtimomines H–K (3–6) are indole alkaloids possessing β-carboline skeleton with an imidazolium unit. Antimicrobial activities of hyrtimomines F–K (1–6) were evaluated.     

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.     

Spironaamidine, a new spiroquinone-containing alkaloid from the marine sponge Leucetta microraphis

Spironaamidine (1), a unique spiroquinone-containing alkaloid, was isolated from the marine sponge, Leucetta microraphis, along with two known imidazole alkaloids, naamidine H (2) and (9E)-clathridine 9-N-(2-sulfoethyl)imine (3). Spironaamidine (1) showed antimicrobial activity against Bacillus cereus.     

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.     

Poecillastrin E,F, and G,cytotoxic chondropsin-type macrolides from a marine sponge Poecillastra sp.

Poecillastrin E (1), F (2), and G (3) were isolated from a marine sponge Poecillastra sp. as the cytotoxic constituents. Their planar structures were determined by analyzing the MS and NMR spectra. They are closely related to the known poecillastrin C (4). The absolute configuration of the β-hydroxyaspartic acid (OHAsp) residue was determined to be D-threo by Marfey's analysis of the hydrolysate. The mode of lactone ring formation of OHAsp residue in 1–3 was determined by selective reduction of the ester linkage followed by acid hydrolysis.     

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.     

Synthesis of CD-ring structure of cortistatin A, an anti-angiogenic steroidal alkaloid from marine sponge

Stereoselective synthesis of the CD-ring structure of cortistatin A (1), a novel anti-angiogenic steroidal alkaloid from Indonesian marine sponge, was achieved. The stereogenic tertiary carbon center bearing the isoquinoline moiety was constructed by 1,3-chiral transfer method using Johnson-Claisen rearrangement of the chiral allylic alcohol 5. Subsequent intramolecular Michael-aldol reaction afforded the targeted trans-hydrindane skeleton with moderate stereoselectivity.     

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).     

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.     

Agelasine G, a new antileukemic alkaloid from the Okinawan marine sponge Agelas sp.

A new antileukemic alkaloid, agelasine G (1a), has been isolated from the Okinawan marine sponge Agelas sp. and its structure elucidated to be a bromopyrrole alkaloid containing 9-methyladenine and diterpene moieties on the basis of the spectroscopic data.     

Halichonic acid,a new rearranged bisabolene-type sesquiterpene from a marine sponge Halichondria sp.

A new compound, halichonic acid (1), was isolated from a marine sponge Halichondria sp., together with (6R,7S)-7-amino-7,8-dihydro-α-bisabolene (2). The structure of 1 was elucidated by spectroscopic analysis and ECD spectrum calculation to be a rearranged bisabolene-type sesquiterpene having a 3-azabicyclo[3.3.1]nonene moiety. Compound 2 was cytotoxic against HeLa cells with an IC₅₀ value of 50?μM, whereas 1 did not show cytotoxicity even at 50?μM. It is possible that 1 is biosynthesized from farnesyl pyrophosphate and glycine, with rearrangement.     

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.     

Synthesis of (±)-halipanicine, a marine sesquiterpene isothiocyanate isolated from an Okinawan marine sponge Halichondria panicea

(±)-Halipanicine, 4-isothiocyanato-1-cadinene, isolated from an Okinawan marine sponge Halichondria panicea was synthesized from (±)-cryptone in 21 steps in 7.7% total yield. The regio- and stereospecific synthesis esablished the relative stereochemistry of halipanicine.     

Exiguolide, a new macrolide from the marine sponge Geodia exigua

A new 20-membered macrolide designated exiguolide has been isolated from the marine sponge Geodia exigua, and its structure determined by interpretation of spectroscopic data. Exiguolide specifically inhibited fertilization of sea urchin (Hemicentrotus pulcherrimus) gametes but not embryogenesis of the fertilized egg.     

Axiplyns A-E, new sesquiterpene isothiocyanates from the marine sponge Axinyssa aplysinoides

Five new isothiocyanate sesquiterpenes, designated axiplyns A-E (1-5) have been isolated, together with two known isothiocyanate sesquiterpenes (6, 7), from the sponge Axinyssa aplysinoides collected at Misali Island, Tanzania. Axiplyns 4 and 5 embody a new indane sesquiterpene skeleton, and compounds 1, 2, and 5 contain unprecedented ring systems, namely a 6,8-dioxabicyclo[3.2.1]octane and a 2-oxabicyclo[2.2.1]heptane. Axiplyns A, B, and C are potent brine shrimp toxins with LD₅₀ values between 1.5 and 1.8 μg/mL.     

Synthesis of tokaramide A, a cysteine protease inhibitor from marine sponge Theonella aff. mirabilis

The first synthesis of tokaramide A (1) is described. Tokaramide A (1) was synthesized via the peptide with a side-chain unprotected arginine residue on Weinreb AM resin by reductive cleavage.     

Stellatolide H,a cytotoxic peptide lactone from a deep-sea sponge Discodermia sp.

Stellatolide H (1) was isolated from a deep-sea sponge Discodermia sp. as the cytotoxic constituent. The planar structure of 1 was elucidated on the basis of the NMR spectroscopic and mass spectrometric data. The absolute configurations of the constituent amino acid residues were determined by the Marfey’s method. Stellatolide H (1) is a peptide lactone of the callipeltin class with its N-terminus blocked by 3-hydroxy-6,8-dimethyldeca-(4Z,6E)-dienoic acid (Hdda).     

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.     

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.