A new cembranolide from the soft coral Sinularia capillosa

Polyoxygenated cembrane-type diterpenes from the Hainan soft coral Lobophytum crassum as a promising source of anticancer agents with ErbB3 and ROR1 inhibitory potential

A detailed chemical investigation of the Hainan soft coral Lobophytum crassum led to the identification of a class of polyoxygenated cembrane-type macrocyclic diterpenes (1-28), including three new flexible cembranoids, lobophycrasins E-G (2-4), and twenty-five known analogues. Their structures were elucidated by combining extensive spectroscopic data analysis, quantum mechanical-nuclear magnetic resonance (QM-NMR) methods, the modified Mosher's method, X-ray diffraction analysis, and comparison with data reported in the literature. Bioassays revealed that sixteen cembranoids inhibited the proliferation of H1975, MDA-MB231, A549, and H1299 cells. Among them, Compounds 10, 17, and 20 exhibited significant antiproliferative activities with IC50 values of 1.92-8.82 μM, which are very similar to that of the positive control doxorubicin. Molecular mechanistic studies showed that the antitumour activity of Compound 10 was closely related to regulation of the ROR1 and ErbB3 signalling pathways. This study may provide insight into the discovery and utilization of marine macrocyclic cembranoids as lead compounds for anticancer drugs.

Cytotoxic Compounds from Alcyoniidae: An Overview of the Last 30 Years

The octocoral family Alcyoniidae represents a rich source of bioactive substances with intriguing and unique structural features. This review aims to provide an updated overview of the compounds isolated from Alcyoniidae and displaying potential cytotoxic activity. In order to allow a better comparison among the bioactive compounds, we focused on molecules evaluated in vitro by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, by far the most widely used method to analyze cell proliferation and viability. Specifically, we surveyed the last thirty years of research, finding 153 papers reporting on 344 compounds with proven cytotoxicity. The data were organized in tables to provide a ranking of the most active compounds, to be exploited for the selection of the most promising candidates for further screening and pre-clinical evaluation as anti-cancer agents. Specifically, we found that (22S,24S)-24-methyl-22,25-epoxyfurost-5-ene-3β,20β-diol (16), 3β,11-dihydroxy-24-methylene-9,11-secocholestan-5-en-9-one (23), (24S)-ergostane-3β,5α,6β,25 tetraol (146), sinulerectadione (227), sinulerectol C (229), and cladieunicellin I (277) exhibited stronger cytotoxicity than their respective positive control and that their mechanism of action has not yet been further investigated.

Semisynthetic and SAR Studies of Amide Derivatives of Neocrotocembraneic Acid as Potential Antitumor Agents

A series of novel amide derivatives of cembranoid neocrotocembraneic acid were designed and synthesized. The antiproliferative activities of these derivatives were evaluated against three human tumor cell lines (the human cervical cancer cell line HeLa, chronic myeloid leukemia cell line K562 and leukemia multidrug-resistant cell line K562/A02). Some of the synthesized compounds exhibited moderate to good activity against all three cancer cell lines. Particularly, compound 8a exhibited more potent antiproliferative activity than the reference drug etoposide against drug-resistant cell line K562/A02, indicating that it possessed a great potential for further development as a multidrug resistance modulator by structural modification.

Structural Elucidation and Structure-Anti-inflammatory Activity Relationships of Cembranoids from Cultured Soft Corals Sinularia sandensis and Sinularia flexibilis

New cembranoids 4-carbomethoxyl-10-epigyrosanoldie E (1), 7-acetylsinumaximol B (2), diepoxycembrene B (6), dihydromanaarenolide I (8), and isosinulaflexiolide K (9), along with 11 known related metabolites, were isolated from cultured soft corals Sinularia sandensis and Sinularia flexibilis. The structures were elucidated by means of infrared, mass spectrometry, and nuclear magnetic resonance techniques, and the absolute configurations of 1, 4, 9, and 15 were further confirmed by single-crystal X-ray diffraction analysis. The absolute configurations of these coral metabolites and comparison with known analogues showed that one hypothesis (that cembrane diterpenes possessing an absolute configuration of an isopropyl group at C1 obtained from Alcyonacean soft corals belong to the α series, whereas analogues isolated from Gorgonacean corals belong to the β series) is not applicable for a small number of cembranoids. An in vitro anti-inflammatory study using LPS-stimulated macrophage-like cell line RAW 264.7 revealed that compounds 9-14 significantly suppressed the accumulation of pro-inflammatory proteins, iNOS and COX-2. Structure-activity relationship analysis indicated that cembrane-type compounds with one seven-membered lactone moiety at C-1 are potential anti-inflammatory agents. This is the first culture system in the world that has successfully been used to farm S. sandensis.

Structural diversity of terpenoids in the soft coral Sinularia flexibilis, evidenced by a collection from the South China Sea

Eight new terpenoids, including a rare biscembranoid and a 15-membered macrocyclic diterpenoid, were isolated from South China Sea soft coral Sinularia flexibilis.

NMR-based metabolomic analysis of spatial variation in soft corals

Soft corals are common marine organisms that inhabit tropical and subtropical oceans. They are shown to be rich source of secondary metabolites with biological activities. In this work, soft corals from two geographical locations were investigated using ¹H-NMR spectroscopy coupled with multivariate statistical analysis at the metabolic level. A partial least-squares discriminant analysis showed clear separation among extracts of soft corals grown in Sanya Bay and Weizhou Island. The specific markers that contributed to discrimination between soft corals in two origins belonged to terpenes, sterols and N-containing compounds. The satisfied precision of classification obtained indicates this approach using combined ¹H-NMR and chemometrics is effective to discriminate soft corals collected in different geographical locations. The results revealed that metabolites of soft corals evidently depended on living environmental condition, which would provide valuable information for further relevant coastal marine environment evaluation.

Cytotoxic and cytolytic cnidarian venoms. A review on health implications and possible therapeutic applications

The toxicity of Cnidaria is a subject of concern for its influence on human activities and public health. During the last decades, the mechanisms of cell injury caused by cnidarian venoms have been studied utilizing extracts from several Cnidaria that have been tested in order to evaluate some fundamental parameters, such as the activity on cell survival, functioning and metabolism, and to improve the knowledge about the mechanisms of action of these compounds. In agreement with the modern tendency aimed to avoid the utilization of living animals in the experiments and to substitute them with in vitro systems, established cell lines or primary cultures have been employed to test cnidarian extracts or derivatives. Several cnidarian venoms have been found to have cytotoxic properties and have been also shown to cause hemolytic effects. Some studied substances have been shown to affect tumour cells and microorganisms, so making cnidarian extracts particularly interesting for their possible therapeutic employment. The review aims to emphasize the up-to-date knowledge about this subject taking in consideration the importance of such venoms in human pathology, the health implications and the possible therapeutic application of these natural compounds.

Asteriscane-type sesquiterpenoids from the soft coral Sinularia capillosa

Chemical examination of the soft coral Sinularia capillosa collected from the South China Sea resulted in the isolation of 14 new asteriscane-type sesquiterpenoids, namely, capillosananes A-N (1-14), four new seco-asteriscanes, capillosananes O-R (15-18), and (-)-sinularone A and sinularone A. Their structures were determined on the basis of extensive spectroscopic analyses, while the absolute configurations were determined by CD and ECD calculation, Mosher's method, and chemical conversion. This is the first report of asteriscane-type sesquiterpenoids from soft corals, and capillosananes Q (17) and R (18) represent new seco-asteriscane skeletons. Capillosanane A exhibited potent antifouling activity against Balanus amphitrite, with an IC₅₀ value of 9.70 μM, while capillosananes B and I and (-)-sinularone A inhibited inflammation-related TNF-α in vitro.

Marine natural products

This review covers the literature published in 2011 for marine natural products, with 870 citations (558 for the period January to December 2011) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1152 for 2011), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

New cembrane diterpenoids from a Hainan soft coral Sinularia sp

Five new cembrane diterpenoids, named sinuflexibilins A-E (1-5), along with nine other known diterpenoids (6-14), have been isolated from the organic extract of a Hainan soft coral Sinularia sp. Their structures were determined on the basis of extensive spectroscopic analyses and by comparison of their spectral data with those of related metabolites. Compound 13, flexibilide, exhibited significant inhibitory activity of NF-κB activation using the cell-based HEK293 NF-κB luciferase reporter gene assay.

Antiviral and anti-inflammatory metabolites from the soft coral Sinularia capillosa

Chemical investigations of the soft coral Sinularia capillosa resulted in the isolation of one new tetraprenylbenzoquinone, capilloquinone (1), two new furanobenzosesquiterpenoids, capillobenzopyranol (2) and capillobenzofuranol (3), one new furanosesquiterpenoid, capillofuranocarboxylate (4), and five previously characterized metabolites, comprising (E)-5-(2,6-dimethylocta-5,7-dienyl)furan-3-carboxylic acid (5), 2-[(2E,6E)-3,7-dimethyl-8-(4-methylfuran-2-yl)octa-2,6-dienyl]-5-methylcyclohexa-2,5-diene-1,4-dione (6), 2-[(2E,6E)-3,7-dimethyl-8-(4-methylfuran-2-yl)octa-2,6-dienyl]-5-methylbenzene-1,4-diol (7), (-)-loliolide (8), and 3,4,11-trimethyl-7-methylenebicyclo[6.3.0]undec-2-en-11alpha-ol (9). The structures of 1-4 were elucidated through extensive spectroscopic analysis. The cytotoxicity, anti-HCMV (human cytomegalovirus) activity, antibacterial activity, and anti-inflammatory effects of 1-9 were evaluated in vitro.

Lactonecembranoids from Croton laevigatus

Six new cembranoids, laevigatlactones A-F (1-6), and the known compound neocrotocembraneic acid (7) were isolated from leaves of Croton laevigatus. Their structures were elucidated on the basis of spectroscopic analysis, and that of 1 was confirmed by X-ray crystallography. Compound 2 exhibited modest cytotoxicity against HeLa cells, with an IC(50) value of 38.4 microM.

Cytotoxic and anti-inflammatory cembranoids from the Dongsha Atoll soft coral Sarcophyton crassocaule

Five new cembranoids, sarcocrassocolides A-E (1-5), along with three known cembranoids 6-8, have been isolated from a Formosan soft coral Sarcophyton crassocaule. The structures of the new metabolites were elucidated by extensive spectroscopic analysis and the absolute configuration of 1 was determined by a modified Mosher's method. Compounds 1-4 exhibited significantly cytotoxic activity against a limited panel of cancer cell lines. Compounds 1-4, 6 and 8 were shown to exert significant in vitro anti-inflammatory activity in LPS-stimulated RAW264.7 macrophage cells. Compound 6 also significantly inhibited the accumulation of pro-inflammatory COX-2 protein.

Oxygenated cembranoids from the cultured and wild-type soft corals Sinularia flexibilis

Two new cembranoids, flexibilisolide A (1) and flexibilisin A (2), along with one known combranoid 5 have been isolated from the cultured soft coral Sinularia flexibilis. Furthermore, two new cembranoids, flexibilisolide B (3) and flexibilisin B (4), along with two known combranoids (5, 6), have been isolated from the wild-type soft coral S. flexibilis. The structures of the new metabolites were determined on the basis of extensive spectroscopic analysis and by comparison of NMR data with those of known compounds. The metabolites 5 and 6 have been shown to exhibit weak cytotoxic activity against MCF-7 cancer cell line.

Crassocolides G-M, cembranoids from the Formosan soft coral Sarcophyton crassocaule

Seven new polyoxygenated cembranoids possessing an alpha-methylene-gamma-lactone group, crassocolides G-M (1-7, resp.), have been isolated from the AcOEt extract of the Formosan soft coral Sarcophyton crassocaule. The structures of compounds 1-7 were established by detailed spectroscopic analyses, including 2D-NMR spectroscopy ((1)H,(1)H-COSY, HMQC, HMBC, and NOESY), while the absolute configuration of 1 was determined using a modified reaction of Mosher's method. The cytotoxicity of compounds 1-7 against a limited panel of cancer cell lines was also determined.

Cytotoxic Effect of the Genus Sinularia Extracts on Human SCC25 and HaCaT Cells

Soft corals of the genus Sinularia are being increasingly adopted to treat a wide variety of disease processes. However, the mechanism underlying its activity against human oral cancer cells is poorly understood. This study evaluates the cyototoxicity effects of the genus Sinularia extracts (S. grandilobata, S. parva, S. triangula, S. scabra, S. nanolobata and S. gibberosa) by SCC25 and HaCaT cells. The cell adhesion assay indicates that extracts reduce the cell attachment. Extracts exhibit a dose-dependent cytotoxic effect using MTS assay.Treatment of extracts to observe the morphological alterations in cells, membrane blebbing, nuclear condensation, and apoptotic bodies is demonstrated. Flow cytometry shows that extracts sensitized the cells in the G₀/G₁ and G₂/M phases with a concomitant significantly increased sub-G₁ fraction, suggesting cell death by apoptosis. Extracts of the genus Sinularia thus apparently cause apoptosis of SCC25 and HaCaT cells, and warrant further research investigating the possible antioral cancer compounds in these soft corals.

Dendronpholides A-R, cembranoid diterpenes from the chinese soft coral Dendronephthya sp

A systematic examination of the Chinese soft coral Dendronephthya sp. resulted in the isolation and characterization of 18 new cembranoid diterpenes, namely, dendronpholides A-R (2-19), along with 11-episinulariolide and an enantiomer of sandensolide. Their structures were determined through extensive spectroscopic (IR, MS, 2D NMR) data analyses and by comparison with those reported in literature. The cytotoxicity of several compounds against human tumor cell lines was also evaluated.

Sinulaflexiolides A-K, cembrane-type diterpenoids from the chinese soft coral Sinularia flexibilis

A bioassay-guided fractionation and chemical examination of the soft coral Sinularia flexibilis resulted in the isolation and characterization of sinulaflexiolides A-K (1-11), along with sinulariolone (12), 5-dehydrosinularolide (13), capillolide (14), sinulariolide (15), 5,8-epoxy-9-acetoxysinulariolide (16), flexibilide (17), dihydroflexibilide (18), and the enantiomer of 14-deoxycrassin (19). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with spectroscopic data reported in the literature. Sinulaflexiolides D and E showed selective inhibitory activity against the gastric gland carcinoma cell line BGC-823 at 8.5 and 0.12 microM, respectively.

Oxygenated cembranoids from a Formosan soft coral Sinularia gibberosa

Chemical investigation of a Formosan soft coral, Sinularia gibberosa, has led to the isolation of eight oxygenated cembranoids, 1- 8, including seven new compounds, gibberosenes A-G ( 2- 8). None of these compounds were found to be cytotoxic toward a limited panel of cancer cell lines. Compound 1 significantly inhibited the accumulation of the pro-inflammatory COX-2 protein of the LPS-stimulated RAW264.7 macrophage cells.

Marine natural products

This review covers the literature published in 2005 for marine natural products, with 704 citations (493 for the period January to December 2005) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (812 for 2005), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Two new bioactive sesquiterpenes from the soft coralSinulariasp

Two new sesquiterpenes, 1S*, 4R*, 5S*, 6R*, 7S*, 10S*-1(5), 6(7)-diepoxy-4-guaiol (1) and 1S*, 4S*, 5S*, 10R*-4,10-guaianediol (2) have been isolated from the ethyl acetate soluble portion of the soft coral Sinularia sp., and their stereostructure were determined by spectroscopic methods and by X-ray single crystal analysis. Both compounds showed antioxidant and cytotoxic activities.

New tetracyclic diterpenoid and new ceramides from the soft coral Sinularia conferta

The new tetracyclic diterpenoid confertdiate (1) and two new ceramides, (2) and (3), have been isolated from the soft coral Sinularia conferta, collected from Sanya Bay, Hainan Island, China. Their structures have been elucidated by spectroscopic analysis, and comparison of the 13C NMR data with those of the known diterpenoid isomandapamate confirmed the structure of 1.