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A new polyketide-based metabolite, spiroplakortone (1), characterized as an unprecedented γ-spiroketal-γ-lactone, was obtained from the Chinese sponge Plakortis simplex. Structural characterization of spiroplakortone (1) was based on extensive spectroscopic analysis and its configuration was partly established by GIAO 13C-NMR, supported by DP4 probability analysis, and ECD calculations. A plausible pathway for the biosynthesis of spiroplakortone (1), envisaging the formation of a carbon–carbon linkage between polyketide and aminoacid (leucine)-derived moieties, has been proposed.

Two new pyridine-containing limonoids, xylogranatopyridines A (I) and B (II) and their formal precursor, prexylogranatopyridine (III), are isolated and evaluated for their protein tyrosine phosphatase 1B (PTP1B) activity.

The isolation, structure elucidation and biosynthetic pathway of the title compound are described.

Two new steroidal derivatives, named clionastatins A and B, have been isolated from the burrowing sponge Cliona nigricans. These molecules are tri-and tetra-chlorinated androstane derivatives, respectively, and they represent the first polyhalogenated steroids found in a natural organism, either marine or terrestrial, and the first examples of halogenated androstanes in nature. Both clionastatins proved to be potently cytotoxic.

Four new diterpenoids (I-III) have been isolated together with five already known, structurally related diterpenoids.

Title compound (I) moderately inhibits LPS-induced NO release, providing interesting insights into the poorly understood SAR for anti-inflammatory glycolipids.

isolation and structure elucidation of cannabioxepane (I), which does not show cannabinoid activity, and isocannabispiradienone (II)

Agelongine ( 1 ), a novel bromopyrrole alkaloid containing a pyridinium ring in place of the imidazole nucleus, usually found in Agelas alkaloids, has been isolated from the Caribbean sponge Agelas longissima , and its structure established by spectroscopic analysis and chemical degradation. Agelongine exhibited an antiserotonergic activity tested in vitro on the rat stomach fundus strip.

A purine derivative. 3,7-dimethylisoguanine ( 1 ), and a novel alkaloid with the unusual pyrrolopiperazine nucleus, longamide ( 2 ), were isolated from the sponge Agelas longissima , and their structures established on the basis of spectroscopic data. In addition, 2 exhibited a mild antibacterial activity.

Clathramide A ( 1a ) and B ( 1b ) are two novel isomeric bromopyrrole alkaloids containing the uncommon N-methylimidazolinium moiety, isolated from the Caribbean sponge Agelas clathrodes . Their structures, elucidated on the basis of a detailed spectroscopic analysis, appear not biosynthetically related to oroidin and its derivatives. In addition, 1a-1b exhibited a mild antifungal activity tested in an agar disk assay on Aspergillus niger .

Four Caribbean Agelas sponges ( A. clathrodes, A. conifera, A. dispar, A. longissima ) have been investigated for the alkaloid composition. Along with a series of known bromopyrrole alkaloids, two related novel compounds of this class, dispacamides C ( 7 ) and D ( 8 ), were found and their structures determined with spectroscopic methods. All the isolated Agelas bromopyrrole alkaloids have been evaluated for the antihistaminic activity on the guinea pig ileum.

The absolute configuration of title compound (I) is tentatively assigned in analogy to that of cannabidiol.

Two novel norlanostane triglycosides, ectyoplasides A (1) and B (2), have been isolated from the methanolic extracts of the Caribbean sponge Ectyoplasiaferox (Raspaliidae, Axinellida). Their structures have been established by extensive application of high-resolution FABMS and two-dimensional NMR techniques, supported by chemical and enzymatic degradation methods. Ectyoplasides A and B have been shown to possess identical sugar chains (composed of two β-galactose units and one α-arabinose unit), but to differ in their aglycone moieties, which possess nortriterpene skeletons with an unprecedented substitution pattern on ring A. Ectyoplasides A and B show moderate cytotoxic activity when tested in vitro towards various cell lines

The polyketides dihydroplakortin ( 3 ), and the dodecanoic acid derivatives 4 and 5 , were isolated from the Caribbean marine sponge Plakortis simplex , and their structures fully characterized by spectroscopic and chemical means. The absolute stereochemistries of the known plakortin ( 1 ) and of compounds 3–5 were determined by applying Mosher's and Kusumi's methods on opportune degradation products. The isolated compounds exhibited cytotoxic activity tested in vitro on WEHI 164, murine fibrosarcoma cell line.

Three novel cembrane diterpenoids, decaryiols B–D (5–7), characterized by a bicyclic skeleton of the decaryiol-type, have been isolated from the Indonesian soft coral Lobophytum sp., along with three known cembranoids. The stereostructures of these metabolites have been established through extensive NMR spectroscopic analysis, application of the modified Mosher method, and chemical conversion. Cembranoids obtained from Lobophytum sp. (2–7) and six semisynthetic derivatives (9–14) prepared from decaryiol were tested for cell growth inhibitory activity against three different cell lines. O-Methyl decaryiol (10) exhibited a significant and selective activity against glioma cell lines.

Four novel xenicane diterpenoids, xenimanadins A–D (1–4), characterized by the unusual 2,6-dimethoxytetrahydropyran functionality, have been isolated from the Indonesian soft coral Xenia sp., together with three known xeniolides. The stereostructure of these metabolites has been established through extensive interpretation of NMR data and application of the modified Mosher method. Xenimanadins were tested against tumor cell lines, revealing details about the cytotoxic potential of xenicane diterpenoids.

A new member of the family of zoanthamine-type alkaloids, lobozoanthamine (1), has been isolated from the Indonesian soft coral Lobophytum sp. This represents the first report of a zoanthamine-type alkaloid from a marine invertebrate different from zoanthids. The densely functionalized heptacyclic stereostructure of lobozoanthamine (1) has been established through the interpretation of 2D NMR data and application of the modified Mosher method.

Seven new diterpenoids belonging to the briarane [erythrolides R (5), S (6), T (7), and U (8)], erythrane [erythrolide V (9)], and aquariane [aquariolides B (10) and C (11)] skeletal classes have been isolated from the encrusting gorgonian Erythropodium caribaeorum. The structures of the new compounds were elucidated by spectroscopic analysis and chemical interconversions. A biogenetic proposal that links carbon skeletons found in E. caribaeorum diterpenoids is presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The novel pyrrole-imidazole alkaloids cyclooroidin (7) and taurodispacamide A (8) have been isolated from the Mediterranean sponge Agelas oroides, and their structures established from spectroscopic data. Although both these alkaloids may be conceived as derivatives of the C11N5 skeleton of the known oroidin (1), remarkably cyclooroidin (7) possesses the unprecedented N1/C9 connection. Taurodispacamide A (8) exhibited a good antihistaminic activity, tested on the isolated guinea pig ileum.