Briaexcavatins M-P, four new briarane-related diterpenoids from cultured octocoral Briareum excavatum (Briareidae)

Four new briarane-related diterpenoids, designated as briaexcavatins M-P (1-4), were isolated from the cultured octocoral Briareum excavatum. The structures, including the relative configurations of natural products 1-4 were established on the basis of extensive spectral data analysis and by comparison with the spectral data from other known metabolites featuring a briarane carbon skeleton.     

Junceellonoids A and B,Two New Briarane Diterpenoids from the Chinese Gorgonian Junceella fragilis Ridley

Two new diterpenoids, junceellonoids A and B ( 1 and 2 , resp.), together with the seven known diterpenoids 3 – 9 , all possessing the briarane carbon skeleton, were isolated from the gorgonian Junceella fragilis Ridley , collected in the South Sea of China. The structures and relative configurations of the new metabolites were elucidated based on extensive spectral analysis and by comparison with known spectral data.     

Cyclobutenbriarein A,the first diterpene with a tricyclo[8.4.0.0(3,6)]tetradec-4-ene ring system isolated from the Gorgonian Briareum asbestinum

Cyclobutenbriarein A (2), a novel class of C20-rearranged diterpene briarane possessing an unprecedented tricyclo[8.4.0.0(3,6)]tetradec-4-ene ring system was isolated, along with five new briarane diterpenoids (1 and 3-6), from the organic extracts of the Bahamian gorgonian Briareum asbestinum. The structures of these secondary metabolites were established on the basis of extensive NMR studies and accurate mass measurements (HRFABMS).     

Briarenol A, a new diterpenoid from a gorgonian '\Briareum sp. (Briareidae)

A new polyoxygenated briarane-type diterpenoid, briarenol A (1), has been isolated from a gorgonian coral belonging to the genus Briareum. The structure, including the relative stereochemistry of briarane 1, was elucidated by the interpretation of spectral data. The configuration of 1 was further supported by molecular mechanics calculations.     

New hydroperoxybriarane diterpenoids from the octocoral Briareum violaceum

A known briarane, brianthein W (1), along with four new hydroperoxybriaranes, briaviolides R–U (2–5), have been obtained from the octocoral Briareum violaceum. The absolute configuration of 1 was determined by X-ray analysis for the first time and the structures of briaranes 2–5 were established by spectroscopic methods. Bioactivity study showed that briarane 3 decreased the production of superoxide anions from human neutrophils.     

Briarane-Related Diterpenoids from Octocoral Briareum stechei

A known polyoxygenated briarane, briaexcavatolide P (1), was isolated from a Formosan octocoral Briareum stechei. Moreover, the same species B. stechei, collected from Okinawan waters, yielded three chlorine-containing briaranes, including two new compounds, briastecholides B (2) and C (3) as well as a known analogue, briarenol R (4). The structures of 1–4 were established using spectroscopic methods. In addition, briarane 1 demonstrated anti-inflammatory activity in lipo-polysaccharide-induced RAW 264.7 mouse macrophage cells by suppressing the expression of inducible nitric oxide synthase (iNOS) protein.     

New metabolites with antibacterial activity from the marine angiosperm Cymodocea nodosa

Four new metabolites (1-4) have been isolated from the organic extract of the seagrass Cymodocea nodosa, collected at the coastal area of Porto Germeno, in Attica Greece. Compounds 1 and 2 belong to the structural class of diarylheptanoids, which have been found only once before in marine organisms [Kontiza, I.; Vagias, C.; Jakupovic, J.; Moreau, D.; Roussakis, C.; Roussis, V. Tetrahedron Lett.2005, 46, 2845-2847]. Compound 3 is a new meroterpenoid, while compound 4, to the best of our knowledge, is the first briarane diterpene isolated from seaweeds, and only the second analog of this class with a tricyclic skeleton. Furthermore metabolite 4 is the first brominated briarane diterpene. The structures and the relative stereochemistry of the new natural products were established by spectral data analyses. The new metabolites were submitted for evaluation of their antibacterial activity against multidrug-resistant (MDR) pathogens including methicillin-resistant (MRSA) strains of Staphylococcus aureus, as well as the rapidly growing mycobacteria, Mycobacterium phlei, Mycobacterium smegmatis, and Mycobacterium fortuitum.     

Juncenolide E,A New Briarane from Taiwanese Gorgonian Junceella Juncea

In addition to junceellolides B ( 3 ) and C ( 4 ), a new briarane, juncenolide E ( 1 ) has been isolated from the acetone extract of the red gorgonian Junceella juncea, collected on the southern coast of Taiwan. The structure of juncenolide E was determined by interpretation of MS, COSY, HMQC, HMBC and NOESY spectra.     

A new spiroketal steroid from Gorgonella umbraculum

A new spiroketal steroid (2) was isolated from the Indian Ocean gorgonian, Gorgonella umbraculum besides the known briarane diterpenoids, juncellin, umbraculides A and D. The new steroid was characterised as 22-acetoxy-3,25-dihydroxy-16-24,20-24-bisepoxy-(3beta, 16alpha, 20S, 22R, 24S)cholest-5-ene (2) by a study of its spectral data.     

Fragilolides A-Q,norditerpenoid and briarane diterpenoids from the gorgonian coral Junceella fragilis

Chemical investigation of the gorgonian coral Junceella fragilis resulted in the isolation of a new norditerpenoid fragilolide A (1), sixteen new briarane diterpenoids fragilolides B-Q (2–17), together with frajunolides H and N, and three known norcembranoids scabrolide D, sinuleptolide and 5-epi-sinuleptolide. The structures of new compounds were determined on the basis of extensive spectroscopic analysis, including the experimental and calculated ECD data and single-crystal X-ray diffraction for the configurational assignments. The structure of fragilolide A featured an unprecedented 4,13- and 7,11-fused tetracyclic norcembranoid, while the biogenetic relationships of the briarane analogues were postulated. Frajunolide H exerted significant inhibition against a panel of tumor cell lines, and six briarane diterpenoids (3, 6, 8, 12, 16, and frajunolide N) exhibited the inhibitory effects against the HBeAg express of hepatitis B virus in HepAD38 cells. In addition, sinuleptolide and 5-epi-sinuleptolide exerted the effects to inhibit NO production in RAW264.7 macrophage cells, in addition to the activation of ARE and the inhibition of NF-κB expression.     

Briarenolide E: the first 2-ketobriarane diterpenoid from an octocoral Briareum sp. (Briareidae)

A novel 2-ketobriarane diterpenoid, briarenolide E (1), was isolated from an octocoral Briareum sp. The structure of briarane 1 was elucidated by interpretations of spectral data. Compound 1 displayed modestly inhibitory effects on the generation of superoxide anions and the release of elastase by human neutrophils.     

Cembranoid diterpenes and a briarane diterpene from corals

Two new cembrane diterpenes (+)-polydactylide (1) and (+)-7alpha,8beta-dihydroxydeepoxysarcophine (2) together with (+)-sarcophine (3) and (+)-sarcophytoxide (4) have been isolated from the soft coral Sinularia polydactyla. The new cembrane diterpene (-)-7beta-hydroxy-8alpha-methoxydeepoxysarcophine (5) has been obtained from the soft coral Sarcophyton trocheliophorum and the known briarane diterpene briaexcavatolide W (6) from the gorgonian coral Briareum sp.The structures were determined primarily by NMR spectroscopy. The assignment of NMR signals was performed by means of (1)H-(1)H COSY, ROESY, HMQC and HMBC experiments.     

Bis-allylic Reactivity of the Funicolides, 5,8(17)-diunsaturated briarane diterpenes of the sea pen Funiculina quadrangularis from the tuscan archipelago,leading to 16-nortaxane derivatives

Funicolides A–C ( 1–3 ), D ( 5 ), and E ( 7 ) and 7-epifunicolide A ( 4 ), new 5,8(17)-diunsaturated briarane diterpenes, as well as the known analogue brianthein W ( 6 ), were isolated from the pennatulacean coral Funiculina quadrangularis (PALLAS , 1766) collected in the Tuscan archipelago. Easy degradation under oxidative and/or basic conditions served to assign the ester groups at C(2) or C(14), while revealing bis-allylic reactivity at C(7) with formation of 16-nortaxane derivatives.     

Isolation of the Cembranoid Preverecynarmin Alongside Some Briaranes,the Verecynarmins,from Both the Nudibranch Mollusc Armina maculata and the Octocoral Veretillum cynomorium of the East Pyrenean Mediterranean Sea

It is shown that the nudibranch mollusc Armina maculata and its prey, the pennatulacean octocoral Veretillum cynomorium, of east Pyrenean waters contain a novel cembranoid, preverecynarmin ((+)- 8 ), besides the known cembranoid cembrene C ( 9 ) and three further briarane diterpenoids (verecynarmin E ((?)- 5 ), F ((?)- 6 ), and G ((?)- 7 )). A biogenetic scheme is proposed.     

Bioactive diterpenoid containing a reversible "spring-loaded" (E,Z)-dieneone Michael acceptor

Three new briarane diterpenoids, briareolate esters L-N (1-3), have been isolated from a gorgonian Briareum asbestinum. Briareolate esters L (1) and M (2) are the first natural products possessing a 10-membered macrocyclic ring with a (E,Z)-dieneone and exhibit growth inhibition activity against both human embryonic stem cells (BG02) and a pancreatic cancer cell line (BxPC-3). Briareolate ester L (1) was found to contain a "spring-loaded" (E,Z)-dieneone Michael acceptor group that can form a reversible covalent bond to model sulfur-based nucleophiles.     

Dichotellides A-E, five new iodine-containing briarane type diterpenoids from Dichotella gemmacea

Five new briarane type diterpenoids, dichotellides A−E (1−5), were isolated from the South China Sea gorgonian Dichotella gemmacea together with four known analogues (6−9). Compounds 1−5 represent the first examples of iodine-containing briarane type diterpenoids from nature. The structures of these diterpenoids were elucidated by spectroscopic analysis, including 1D, 2D-NMR, and HRESIMS, and the absolute configuration of 1 was further confirmed by single crystal X-ray diffraction analysis. All the isolates were evaluated for cytotoxicity activity against four human tumor cell lines, and only 3 exhibited marginal activity against SW1990 (human pancreatic cancer).     

New Briaranes from the South China Sea Gorgonian Junceella fragilis

Three new briarane diterpenes, junceellonoids C–E ( 1 – 3 ), along with six known briaranes, junceellin A ( 4 ), praelolide ( 5 ), and junceellolides A‐D ( 6 – 9 ), were isolated from the EtOH/CH₂Cl₂ extracts of the South China Sea gorgonian coral Junceella fragilis. The structures of 1 – 3 were established by extensive spectroscopic analysis, including 1D‐ and 2D‐NMR data. Compounds 1 and 2 exhibited mild cytotoxicity against human galactophore carcinoma (MDA‐mB‐231 and MCF‐7) cells at the concentration of 100 μM .     

Chlorinated briarane-type diterpenoids from the gorgonian coral Ellisella robusta (Ellisellidae)

Four chlorinated metabolites featuring briarane carbon skeletons have been isolated from the gorgonian coral Ellisella robusta, which was collected off the coast of southern Taiwan: two new natural products, robustolides D (1) and E (2), and two known metabolites, robustolides F (3) and G (4). The structures of metabolites 1–4 were determined by spectroscopic methods, using 1D and 2D NMR in particular. The structures and absolute stereochemistry of robustolides D (1), F (3), and G (4) were directly established by X-ray diffraction analysis. Robustolide D (1) is the first metabolite of briarane-related natural products found to possess two halogen atoms.     

Briaexcavatolides X-Z, three new briarane-related derivatives from the gorgonian coral Briareum excavatum

Three new polyoxygenated briarane-type diterpenoids, briaexcavatolides X-Z (1-3), have been isolated from the gorgonian coral Briareum excavatum. The structures, including the relative configurations of briaranes 1-3, were elucidated by spectroscopic methods, particularly in 1D and 2D NMR experiments. The configuration of briarane 1 was further supported by molecular mechanics calculations.     

spiro-Mamakone A: a unique relative of the spirobisnaphthalene class of compounds

[structure: see text] A spirobisnaphthalene derivative with a new spiro-nonadiene skeleton, spiro-mamakone A (1), has been isolated from the extract of a cultured nonsporulating fungal endophyte derived from the New Zealand native tree Knightia excelsa (rewarewa). The carbon skeleton of spiro-mamakone A represents a new structural entity and an intriguing addition to the structurally diverse spirobisnaphthalene group of compounds. spiro-Mamakone A is potently cytotoxic and is also antimicrobial.