Polycyclic Guanidine Alkaloids from Poecilosclerida Marine Sponges.

Sessile marine sponges provide an abundance of unique and diversified scaffolds. In particular, marine guanidine alkaloids display a very wide range of biological applications. A large number of cyclic guanidine alkaloids, including crambines, crambescins, crambescidins, batzelladines or netamins have been isolated from Poecilosclerida marine sponges. In this review, we will explore the chemodiversity of tri- and pentacyclic guanidine alkaloids. NMR and MS data tools will also be provided, and an overview of the wide range of bioactivities of crambescidins and batzelladines derivatives will be given.

Nepheliosyne B, a new polyacetylenic acid from the new caledonian marine sponge Niphates sp.

A new C47 polyoxygenated acetylenic acid, nepheliosyne B (2), along with the previously described nepheliosyne A (1), have been isolated from the New Caledonian marine sponge Niphates sp. Their structures have been elucidated on the basis of extensive spectroscopic analyses. These metabolites exhibited a moderate cytotoxicity against K562, U266, SKM1, and Kasumi cancer cell lines.

Cytotoxic and haemolytic steroidal glycosides from the Caribbean sponge Pandaros acanthifolium.

Six new steroidal saponins, pandarosides K-M (1-3) and their methyl esters (4-6), were isolated as minor components, after a careful chemical reinvestigation of the Caribbean sponge Pandaros acanthifolium. Their structures were established on the basis of spectroscopic analyses and comparison with the data obtained from previous metabolites of this family. All new compounds showed moderate to weak activity against four parasitic protozoa. Additionally, these compounds and previously reported pandarosides and acanthifoliosides were tested on three human tumour cell lines, and their haemolytic and liposome permeabilizing activity were assessed. Two pandarosides exhibited moderate to strong cytotoxic effect, while three acanthifoliosides showed strong haemolytic activity.

A new hydroxylated nonaprenylhydroquinone from the Mediterranean marine sponge Sarcotragus spinosulus.

Chemical investigation of the Mediterranean sponge Sarcotragus spinosulus led to the isolation of a new hydroxylated nonaprenylhydroquinone, along with two known metabolites, hepta- and octaprenylhydroquinones. The structure of the new metabolite was assigned by extensive 1D and 2D NMR analyses and MS studies. The antileukemic effect of the three compounds towards the chronic myelogenous leukemia (CML) cells line K562 was also evaluated.

Antiprotozoal steroidal saponins from the marine sponge Pandaros acanthifolium.

The chemical composition of the Caribbean sponge Pandaros acanthifolium was reinvestigated and led to the isolation of 12 new steroidal glycosides, namely, pandarosides E-J (1-6) and their methyl esters (7-12). Their structures were determined on the basis of extensive spectroscopic analyses, including two-dimensional NMR and HRESIMS data. Like the previously isolated pandarosides A-D (13-16), the new compounds 1-12 share an unusual oxidized D-ring and a cis C/D ring junction. The absolute configurations of the aglycones were assigned by interpretation of CD spectra, whereas the absolute configurations of the monosaccharide units were determined by chiral GC analyses of the acid methanolysates. The majority of the metabolites showed in vitro activity against three or four parasitic protozoa. Particularly active were the compounds 3 (pandaroside G) and its methyl ester (9), which potently inhibited the growth of Trypanosoma brucei rhodesiense (IC(50) values 0.78 and 0.038 microM, respectively) and Leishmania donovani (IC(50)'s 1.3 and 0.051 microM, respectively).

Plumisclerin A, a diterpene with a new skeleton from the soft coral Plumigorgia terminosclera.

A novel compound, named plumisclerin A (1), was isolated from samples of the soft coral Plumigorgia terminosclera collected at Mayotte Island. The compound possesses the novel plumisclerane carbon skeleton, including a tricyclo[4,3,1,0(1,5)]decane ring. Its structure and relative stereochemistry were elucidated by extensive spectroscopic analysis, including HREIMS, COSY, HSQC, HMBC, TOCSY, and NOESY experiments. In addition, the novel compound displayed in vitro cytotoxicity against selected cancer cell lines.

Bioactive guanidine alkaloids from two Caribbean marine sponges.

Seven new guanidine alkaloids (1-7) together with the known batzelladines A, F, H, and L, ptilomycalin A, and fromiamycalin were isolated from the Caribbean marine sponges Monanchora arbuscula and Clathria calla. Molecular structures were assigned on the basis of detailed analysis of 1D and 2D NMR spectra and mass spectrometry data, and bioactivities of the alkaloids were evaluated against human cancer cell lines and malaria protozoa.

Parazoanthines A-E, hydantoin alkaloids from the Mediterranean sea anemone Parazoanthus axinellae.

Five new hydantoin alkaloids, named parazoanthines A-E (1-5), were isolated as the major constituents of the Mediterranean sea anemone Parazoanthus axinellae. Their structural elucidation was achieved through NMR spectroscopic and mass spectrometric analyses. The absolute configuration of the chiral compounds 1 and 4 was determined by comparison between experimental and TDDFT-calculated CD spectra. The configuration of the trisubstituted double bond of 2, 3, and 5 was deduced from the (3)J(H6-C4) coupling constant value. This family of alkaloids represents the first example of natural 3,5-disubstituted hydantoins that do not exhibit a methyl at N-3. All compounds were tested for their natural toxicity (Microtox assay), and parazoanthine C (3) exhibited the highest natural toxicity.

Steroidal glycosides from the marine sponge Pandaros acanthifolium.

The chemical composition of the Caribbean sponge Pandaros acanthifolium was investigated and led to the isolation of seven new steroidal glycosides namely pandarosides A-D (1, 3, 4 and 6) along with the three methyl esters of pandarosides A, C, and D (2, 5 and 7). Their structures were characterized as 3beta-[beta-glucopyranosyl-(1-->2)-beta-glucopyranosyloxyuronic acid]-16-hydroxy-5alpha,14beta-poriferast-16-ene-15,23-dione (1) and its methyl ester (2), 3beta-[beta-glucopyranosyloxyuronic acid]-16-hydroxy-5alpha,14beta-poriferast-16-ene-15,23-dione (3), 3beta-[beta-glucopyranosyl-(1-->2)-beta-glucopyranosyloxyuronic acid]-16-hydroxy-5alpha,14beta-cholest-16-ene-15,23-dione (4) and its methyl ester (5), 3beta-(beta-glucopyranosyloxyuronic acid)-16-hydroxy-5alpha,14beta-cholest-16-ene-15,23-dione (6) and its methyl ester (7) on the basis of detailed spectroscopic analyses, including 2D NMR and HRESIMS studies. Pandarosides A-D and their methyl esters (1-7) are all characterized by a rare 2-hydroxycyclopentenone D-ring with a 14beta configuration. The absolute configuration of the aglycon part of pandaroside A (1) was assigned by comparison between experimental and TDDFT calculated circular dichroism spectra on the more stable conformer.

Acerolide, a new cytotoxic cembranolide from the soft coral Pseudopterogorgia acerosa.

A new cembranolide, acerolide (1) together with the known compound pseudopterolide (2) were isolated from the 2-propanol extract of the soft coral Pseudopterogorgia acerosa. The structure of 1 was determined on the basis of detailed spectroscopic analysis. Compound 1 showed moderate in vitro cytotoxicity against a panel of 14 tumor cell lines.

Halogenated helianane derivatives from the sponge Spirastrella hartmani.

Two new halogenated derivatives (1 and 2) of helianane (3) were isolated from the 2-propanol extract of the sponge Spirastrella hartmani. The structures of the new derivatives were determined on the basis of detailed spectroscopic analysis, including (+)-HREIMS and 1D and 2D NMR. Compound 1 showed in vitro cytotoxicity against the human tumor cell lines A549, HT29, and MDA-MB-231.

Sodwanone S, a triterpene from the marine sponge Axinella weltneri.

The bioassay-guided fractionation of the crude extract of the marine sponge Axinella weltneri led to the isolation and the identification of a new triterpene named sodwanone S (1), with an uncommon oxepane-cyclohexane system, along with the known sodwanones A and G. The structure was elucidated using spectroscopic data, and the biological activity was evaluated against 13 human tumor cell lines. A biogenetic pathway of this new compound is also proposed.

Iso-, nor-, and dinor-spiculoic acids A, polyketides from the marine sponge Plakortis zyggompha.

The new iso-, nor-, and dinor-spiculoic acids A (1, 2, and 3, respectively) with a rare spiculane skeleton were isolated from the marine sponge Plakortis zyggompha, collected in the waters south of Martinique. The structural determination of the compounds was based on 1D and 2D NMR studies and mass spectral determinations. Compounds 1 and 2 showed weak cytotoxicity against the two tumor cell lines A549 and HT29.

New cytotoxic steroids from the Indian Ocean sponge Axinella cf. bidderi.

Four new sterols have been isolated from the marine sponge Axinella cf. bidderi, 17alpha-hydroxy-22,23-epoxy-24-methylcholest-5-en-3beta-ol (1) and 17alpha-hydroxy-22,23-epoxycholest-5-en-3beta-ol (2), together with 3 and 4, which possess respectively the cholestene and the cholestane skeleton with a cyclic enol ether linkage between C-18 and C-22. The structures were elucidated using spectroscopic data. The in vitro activity was evaluated against prostate, ovary, pancreas, colon, and lung cell lines.

Yardenone A and B: new cytotoxic triterpenes from the Indian Ocean sponge Axinella cf. bidderi.

Two new polyepoxysqualene-derived triterpenes, yardenone A (1) and B (2), together with the known yardenone (3) and sodwanone A (4), have been isolated from the marine sponge Axinella cf. bidderi from Yemen's Socotra Island in the Indian Ocean. The structures were elucidated using spectroscopic data. The relative stereochemistry was established by the analysis of ROESY spectra as well as coupling constants and molecular modeling. Furthermore, the absolute configuration of 1 was confirmed by the advanced Mosher's method. The cytotoxicity of these compounds was evaluated against a NSCLC cell line.

Variations in caulerpenyne contents in Caulerpa taxifolia and Caulerpa racemosa.

Caulerpenyne (CYN) contents was measured in two Chlorophyceae algae, Caulerpa taxifolia and Caulerpa racemosa, between July 1999 and July 2000. Sampling was performed at three stations exhibiting increasing levels of competition with the seagrass Posidonia oceanica. Significant differences were observed as a function of the Caulerpa species, the season, and the level of competition. CYN concentrations were always greater in C. taxifolia, regardless of either season or level of competition (35-80 times greater, according to the season). For a given species, maximum concentrations were recorded in autumn (September/November) and minimum values occurred in spring (April/May). CYN contents decreased with increasing level of competition, whereas frond length increased over this same gradient. It would appear that when the algae are in competition with P oceanica, Caulerpa is more inclined to accelerate vegetative growth (competition for light) than to produce secondary metabolites.