Stolonilactone, a novel terpenoid-related compound, isolated from the Okinawan soft coral Clavularia koellikeri

A novel terpenoid-related compound, stolonilactone (1), was isolated from the Okinawan soft coral Clavularia koellikeri. The structure of 1 was elucidated on the basis of spectroscopic analysis. A possible biogenesis of 1 through the [4 + 2]-cycloaddition of a trisnorsesquiterpenoid-type diene and a cembranolide-type dienophile is proposed.     

Two new diterpenoids from the marine Soft coral Clavularia viridis

Two new dolabellane diterpenoids named clavudiol B(2)and clavirolide F(5),have been iso-lated from the soft coral Clavularia viridis,collected from Xisha Islands in the South China Sea.Theirstructures have been determined as 2 and 5 by spectral analysis and chemical reactions.     

Isolation of three marine prostanoids,possible biosynthetic intermediates for clavulones,from the Okinawan soft coral Clavularia viridis

Three marine prostanoids, 1, 2, and 3, were isolated from the extract of the Okinawan soft coral Clavularia viridis. The structures of these compounds were assigned based on the results of spectroscopic analysis. Compound 1 was shown to be preclavulone-A methyl ester, and this is the first isolation of the ester of preclavulone-A as a natural product. Preclavulone-A is proposed to be the key intermediate in the biosynthesis of marine prostanoids exemplified by clavulones in C. viridis. The new prostanoid 3 was suggested to be a biosynthetic intermediate from preclavulone-A to clavulones, and a possible biogenetic pathway via 3 is proposed.     

Clavirolide G,a new rare dolabellane-type diterpenoid from the Xisha soft coral Clavularia viridis

One new dolabellane-type diterpenoid,named clavirolide G(1),and one known related analogue(3), have been isolated from the soft coral Clavularia viridis collected off the Xisha Islands in the South China Sea.Its structure and absolute configuration were determined on the basis of spectroscopic analysis, electronic circular dichroism,and compared with literature model compounds.The cytotoxic activity of these two compounds was evaluated against a panel of human tumor cell lines.Compound 1 showed moderate cytotoxic activity against KB and HL-60 cells.     

A new dolabellane diterpene and a new polyacetylene from the soft coral Clavularia viridis

A new dolabellane diterpene (1) and a new polyacetylene (2) were isolated from the soft coral Clavularia viridis. The structures of 1 and 2 were elucidated by spectroscopic analyses including 1D and 2DNMR experiments and HRESIMS data. The absolute configuration of 1 was determined by the modified Mosher’s method and 2 by ECD calculations. Compound 1 exhibited moderate cytotoxicities against MCF-7 and A549 cell lines with IC₅₀ values of 10.5 and 12.6 µM, respectively.     

Isolation of peridinin-related norcarotenoids with cell growth-inhibitory activity from the cultured dinoflagellate of Symbiodinium sp., a symbiont of the Okinawan soft coral Clavularia viridis,and analysis of fatty acids of the dinoflagellate

Two norcarotenoids, 1 and 2, related to peridinin (3) were isolated from the cultured dinoflagellate of the genus Symbiodinium, a symbiont of the Okinawan soft coral Clavularia viridis, which contains in abundance antitumor marine prostanoids such as clavulones. The structures of 1 and 2 were elucidated on the basis of spectroscopic analysis. These compounds showed significant growth-inhibitory activity in vitro toward cancer cells. Analysis of fatty acids of the dinoflagellate was also carried out, suggesting that the marine prostanoids are produced by the host soft coral itself.     

A new rearranged dolabellane diterpene from the soft coral Clavularia inflata

A new dolabellane type diterpene 1 has been isolated through its acetate 1a. The structure of 1a was elucidated by extensive 1D and 2D NMR spectroscopy and confirmed by mass spectrometry. The structure of 1 was deduced by comparison of its NMR spectral data with those of 1a, while its relative stereochemistry was deduced by NOESY. The absolute stereochemistry of C-7 was determined by analyses of 1 separately esterified with R and S O-mandelic acids.     

Marine diterpenoids with a briarane skeleton from the Okinawan soft coral Pachyclavularia violacea

Five new briarane-type diterpenoids, pachyclavulides E (5), F (6), G (7), H (8) and I (9), were isolated from the Okinawan soft coral Pachyclavularia violacea. The structures of these compounds were elucidated based on the results of spectroscopic analysis. Compound 5 showed a weak growth-inhibitory activity in vitro toward cancer cells.     

Purealin,a novel enzyme activator from the Okinawan marine sponge Psammaplysilla purea

Purealin , a novel secondary metabolite, which modurates enzymic reactions of ATPases, has been isolated from the okinawan marine sponge $\text{Psammaplysilla}$$\text{purea}$ and the structure has been determined by the ¹H-¹H homonuclear and ¹H-¹³C heteronuclear NMR chemical shift correlations and CD spectra.     

Structure of an unsaturated fatty acid with unique vicinal dimethyl branches isolated from the Okinawan soft coral of the genus Sinularia

A new unsaturated fatty acid with unique vicinal dimethyl branches was isolated from the Okinawan soft coral of the genus Sinularia. The structure of the compound was determined based on the results of spectroscopic analysis and chemical conversion. The absolute configuration was deduced by applying the Ohrui-Akasaka method.     

Alcyonolide,a novel diterpenoid from a soft coral

A novel diterpenoid acetate named alcyonolide has been isolated from an Okinawan soft coral of the genus $\text{Alcyonium}$ and the absolute stereostructure $\text{1}$ has been assigned on the basis of chemical and physicochemical evidence.     

Stoloniferone-a, -b, -c,and -d,four new cytotoxic steroids from the okinawan soft coral clavularia viridis

Four new cytotoxic steroids named stoloniferone-a (7a), -b (7b), -c (7c), and -d (7d) were isolated from the stoloniferan Okinawan soft coral Clavularia viridis and their absolute stereostructures were elucidated.     

Cladioxazole: a novel sesquiterpene from a marine soft coral of genus Cladiella

Chemical investigations on the methanolic extract of Cladiella species, collected from Andaman Island, India, yielded a novel sesquiterpene, cladioxazole (1). Its structure was established with the aid of extensive spectral studies.     

Sinulochmodins A-C, three novel terpenoids from the soft coral Sinularia lochmodes

An unprecedented C,C-linked dimeric norcembranoid (sinulochmodin A, 1), a novel isocembranoid (sinulochmodin B, 2), and a novel yonarane norditerpenoid (sinulochmodin C, 3) were isolated from the soft coral Sinularia lochmodes. The structures of these metabolites were elucidated by extensive spectroscopic analysis and on the basis of the absolute structures of two related norditerpenoids (4 and 5), which were determined for the first time by a modified Mosher method. A plausible pathway for the biosynthesis of 1 and 3-5 from 2 was postulated. [structure: see text]     

Two new cembrane-based diterpenoids from the marine soft coral Sinularia crassa

Two new cembrane diterpenes, sicrassarines A and B, were isolated from the Taiwanese soft coral Sinularia crassa. The structures of the new metabolites were determined on the basis of extensive spectroscopic analysis, particularly mass spectroscopy and 2D NMR (1H--1H COSY, HMQC, HMBC, and NOESY) spectroscopy.     

Structure and bioactivity of a trisnorditerpenoid and a diterpenoid from an Okinawan soft coral, Cespitularia sp.

An Okinawan soft coral Cespitularia sp. has proven to be a good source of cytotoxic metabolites having a carbon skeleton of the seco-type variety of xenicin. This soft coral yielded alcyonolide, the major constituent, and other related compounds, all of which have proven to be cytotoxic. Reinvestigation of the cytotoxic ethyl acetate extracts of the coral yielded two new alcyonolide congeners, trisnorditerpenoid 1 and diterpenoid 2, possessing the same carbon skeleton. Their structures were elucidated by a detailed analysis of spectroscopic data (1D, 2D NMR, and MS). Metabolites 1 and 2 showed cytotoxicity against HCT116 cells (IC₅₀ 6.04 and 47.0 μM, respectively) and a dose dependent, anti-inflammatory effect in LPS/IFN-γ-stimulated inflammatory RAW 264.7 macrophage cells.