8,17-Epoxybriarane diterpenoids, briaranolides A-J, from an Okinawan Gorgonian Briareum sp

Ten new 8,17-epoxybriarane diterpenoids, briaranolides A-J (1-10), were isolated from an Okinawan gorgonian Briareum sp. The structure of the diterpenoids was determined on the basis of spectroscopic analysis, chemical conversions, and X-ray analysis.     

Brominated sesquiterpenes from the red alga Laurencia obtusa

Four new sesquiterpenes, (8R)-8-bromo-10-epi-beta-snyderol (1), (8S)-8-bromo-beta-snyderol (2), 5-bromo-3-(3'-hydroxy-3'-methylpent-4'-enylidene)-2,4,4-trimethylcyclohexanone (3), and the epoxide 4, have been isolated from the chloroform-methanol extract of Laurencia obtusa, together with the three known compounds alpha-snyderol (5), alpha-snyderol acetate (6), and stigmasterol. The structures of the isolated compounds were elucidated through spectroscopic analyses. Compound 1 showed antimalarial activity, with IC(50) values of 2700 and 4000 ng/mL against the D6 and W2 clones of Plasmodium falciparum, respectively.     

Halogenated metabolites from the new Okinawan red alga Laurencia yonaguniensis

A novel brominated diterpene based on the rare neoirieane skeleton, named neoirietetraol (1), has been isolated along with a halogenated C15 acetogenin, (3Z)-laurenyne (2), from a new Laurencia species, L.yonaguniensis Masuda et Abe, species inedita, collected at Yonaguni Island, Okinawa Prefecture, Japan. The structures of these metabolites were elucidated by spectroscopic data (IR, 1H NMR, 13C NMR, 2D NMR, and MS). Neoirietetraol (1) was toxic to the brine shrimp (Altemia salina; LC50, 40.1 microM) and also showed weak antibacterial activities against two marine bacteria, Alcaligenes aquamarinus and Escherichia coli.     

Briarane-type diterpenoids from the Okinawan soft coral Pachyclavularia violacea

Four new briarane-type diterpenoids, pachyclavulides A (1), B (2), C (3), and D (4), were isolated from the Okinawan soft coral Pachyclavularia violacea. The structures of these compounds were elucidated on the basis of the results of spectroscopic analysis. The absolute configuration of pachyclavulide A (1) was determined by the X-ray crystallographic analysis of its p-bromobenzoyl ester.     

New marine diterpenoids from the Okinawan soft coral Clavularia koellikeri

Chemical investigation of the Okinawan soft coral Clavularia koellikeri resulted in the isolation of two new cembrane diterpenoids (1 and 2) and one new dollabelane diterpenoid, 3. Their structures were determined on the basis of the results of spectroscopic analysis. Compounds 1 and 3 were examined for in vitro growth-inhibition effects toward tumor cells.     

New cytotoxic furanosesterterpenes from an Okinawan marine sponge,Ircinia sp

Five new sesterterpenes have been isolated from a lipophilic extract of a sponge, Ircinia sp., and their structures elucidated by spectroscopic and chemical methods. The absolute configurations of two metabolites (1, 3) were established by chemical degradation. These compounds showed moderate cytotoxicity against KB cells.     

New marine cembrane-type diterpenoids from the Okinawan soft coral Clavularia koellikeri

Seven new marine diterpenoids having a cembrane skeleton were isolated from the Okinawan soft coral Clavularia koellikeri. Their structures were determined based on the results of spectroscopic analysis and chemical conversions. Compound 1 showed cytotoxic activity against human colorectal adenocarcinoma cells (DLD-1, IC(50) 4.2 g/mL) and strong growth inhibition against human T lymphocytic leukemia cells (MOLT-4, IC(50) 0.9 g/mL).     

New marine sesquiterpenoids and diterpenoids from the Okinawan soft coral Clavularia koellikeri

Six new terpenoids (two maaliane-type sesquiterpenoids, 1 and 2, one aromadendrane-type sesquiterpenoid, 3, one noraromadendrane-type sesquiterpenoid, 4, and two neodolabellane-type diterpenoids, 5 and 6) were isolated from the Okinawan soft coral Clavularia koellikeri. The structures of these compounds were determined on the basis of the results of spectroscopic analysis, chemical conversion, and X-ray crystallographic analysis. Compound 6 exhibited modest growth-inhibition effect in vitro toward tumor cells.     

Brominated polyacetylenes from the Philippines sponge Diplastrella sp

Five novel brominated polyacetylenic diols, diplynes A-E (2-6), and three sulfated analogues, diplyne A 1-sulfate (7), diplyne C 1-sulfate (8), and 2-deoxydiplyne D sulfate (9), were isolated from the Philippines sponge Diplastrella sp. by employing bioassay-guided fractionation using the HIV-1 integrase inhibition assay. The novel metabolites were characterized by interpretation of spectroscopic data.     

Brianodins A-D, briarane-type diterpenoids from soft coral Pachyclavularia sp

Four new briarane-type diterpenoids, brianodins A-D ( 1- 4), were isolated from a soft coral, Pachyclavularia sp., and the structures and relative stereochemistry of 1- 4 were elucidated on the basis of spectroscopic data. The absolute configurations of 3 and 4 were assigned by the MTPA method. Brianodin A ( 1) showed a modest cytotoxicity.     

New Xenia diterpenoids from the Indonesian soft coral Xenia sp

Two new xeniolides, xeniolide-F (1) and 9-hydroxyxeniolide-F (2), along with isoxeniolide-A (3) and 7,8-oxido-isoxeniolide-A (4), have been isolated from Xenia sp. and their structures established on the basis of extensive NMR and MS studies.     

Spongian diterpenoids from the sponge Spongia (Heterofibria) sp

Five new (1, 2, 4-6) and one known (3) diterpenoid were isolated from the keratose sponge Spongia (Heterofibria) sp. Structures of these compounds and their absolute configurations were proposed on the basis of X-ray analysis of 1, its CD spectrum, and NMR and MS spectroscopic studies of 1-6. One of the new diterpenoids was shown to be 2(R),3(S),4(S)-3,18-methylene-2-acetoxyspongia-13(16),14-diene (6), possessing a novel carbon skeleton system.     

Terpenoids from Laurencia luzonensis

Luzodiol (4), a diterpene possessing a new carbon skeleton, and five new sesquiterpenes (5-9) of the snyderane class have been isolated from the red alga Laurencia luzonensis and their structures determined by spectroscopic analysis. The relative stereochemistry of the known luzonensol (3) was assigned by its conversion to palisadin B (10).     

Terpene isocyanides, isocyanates, and isothiocyanates from the Okinawan marine sponge Stylissa sp

Seven new nitrogenous terpenoids, (1R,6R,7S,10S)-10-isothiocyanatocadin-4-ene (1), (1S,2S,5S,6S,7R,8S)-13-isothiocyanatocubebane (2), (1R,3S,4R,7S,8S,12S,13S)-7-isocyanoamphilecta-10,14-diene (3), (1S,3S,4R,7S,8S,12S,13S)-8-isocyanoamphilecta-11(20),14-diene (4), (3S,4R,7S,8S,11S,13S)-8-isocyanoamphilecta-1(12),14-diene (5), 8-isocyanatocycloamphilect-10-ene (6), and 8-isothiocyanatocycloamphilect-10-ene (7), were isolated from the Okinawan sponge Stylissasp., along with 12 known related compounds. Structural determinations of these compounds were made by spectroscopic analysis, and assessment was made of their cytotoxicity toward HeLa cells.     

Bisabolanes from the red alga Laurencia scoparia

Three novel halogenated beta-bisabolene sesquiterpenoids (1-3), together with two know triquinane alcohol sesquiterpenes (6 and 7), were isolated from the red alga Laurencia scoparia and their structures elucidated by spectroscopic methods. Single-crystal X-ray crystallography allowed us to confirm the structure of 1 as well as to determine the absolute configuration of all stereocenters. To the best of our knowledge, the isolation of beta-bisabolenes from the genus Laurencia has no precedent in the literature. Compound 1 showed weak in vitro anthelmintic activity against parasitant stage (L4) Nippostrongilus brasiliensis.     

中国东海冈村凹顶藻 Laurencia okamurai 中的倍半萜类成分

目的：对采自中国东海的红藻冈村凹顶藻 Laurencia okamurai 的化学成分进行研究, 从中寻找具有生物活性的次生代谢产物。方法：运用硅胶柱层析和凝胶柱层析对冈村凹顶藻的乙醚提取物进行分离纯化; 根据其理化性质, 结合现代波谱分析技术（MS, NMR 等）并与文献报道的化合物数据相比较, 对分离得到的化合物进行结构鉴定。结果：从冈村凹顶藻中分离并鉴定了 9 个倍半萜类化合物, 分别为 laurokamurene C （1）, debromoaplysinol （2）, aplysinol acetate （3）, debromoisolaurinterol （4）, iso-laurinterol （5）, filiformin （6）, α-isobromocuparene （7）, cuparene-type ether （8） 和 deoxyprepacifenol （9）。结论：化合物 1 为新化合物, 是天然界中发现的第三个重排的月桂烷型倍半萜, 3 系首次从天然界分离得到, 化合物 2-9 对真菌 Cladosporium cucumerinum 均无明显的抑制活性。     

Sesquiterpenes from the red alga Laurencia tristicha

Seven new sesquiterpenes (1-7), together with seven known sesquiterpenes, aplysin (8), aplysinol (9), gossonorol (10), 7,10-epoxy-ar-bisabol-11-ol (11), 10-epi-7,10-epoxy-ar-bisabol-11-ol (12), johnstonol (13), and laurebiphenyl (14), have been isolated from the red alga Laurencia tristicha. The structures of new compounds were established as laur-11-en-2,10-diol (1), laur-11-en-10-ol (2), laur-11-en-1,10-diol (3), 4-bromo-1,10-epoxylaur-11-ene (4), cyclolauren-2-ol (5), laurentristich-4-ol (6), and ar-bisabol-9-en-7,11-diol (7) by means of spectroscopic methods including IR, HRMS, and 1D and 2D NMR techniques. Compound 6 possessed a novel rearranged skeleton. All compounds were tested against several human cancer cell lines including lung adenocarcinoma (A549), stomach cancer (BGC-823), hepatoma (Bel 7402), colon cancer (HCT-8), and HELA cell lines. Laurebiphenyl (14) showed moderate cytotoxicity against all tested cell lines, with IC(50) values of 1.68, 1.22, 1.91, 1.77, and 1.61 microg/mL, respectively. Other compounds were inactive (IC(50) > 10 microg/mL).     

Synthesis of bromoindole alkaloids from Laurencia brongniartii

A regioselective synthesis of N-carbomethoxy-2,3,5-tribromoindole (6) via a sequential one-pot bromination-aromatization-bromination of N-carbomethoxyindoline (2) is described. The process for the transformation of 2 into 6 permitted the isolation of stable reaction intermediates N-carbomethoxy-5-bromoindoline (3), N-carbomethoxy-5-bromoindole (4), and N-carbomethoxy-3,5-dibromoindole (5). Compound 6 was used to complete the total synthesis of the natural products 1b and 1c. In addition, bromination of N-carbomethoxyindole (11) afforded N-carbomethoxy-2,3,6-tribromoindole (13), from which the natural product 1a was synthesized.     

Nonterpenoid C15 acetogenins from Laurencia marilzae

Eight new halogenated C(15) acetogenins, 1-8, were isolated from the organic extract of the red alga Laurencia marilzae. The structure elucidation and the assignments of the relative configurations were established by extensive use of spectroscopic studies, particularly 1D and 2D NMR data, while the absolute configurations of compounds 1 and 5 were determined by single-crystal X-ray diffraction analysis. Compounds 1, 2, 4, 5, and 7, along with the previously reported related cyclic ether obtusallene IV (9), were evaluated against six human solid tumor cell lines. All compounds were found to be essentially inactive (GI(50) > 10 μg/mL).     

Clerodane diterpenoids from Salvia splendens

Four new clerodane diterpenoids, salvisplendins A-D (1-4), have been isolated from an acetone extract of the flowers of Salvia splendens, together with an artifact (5), arising from salvisplendin D (4) by addition of diazomethane, and the already known clerodane olearin (6). The structures of the new compounds (1-5) were established mainly by 1D and 2D NMR spectroscopic studies and, in the case of salvisplendin A (1), by chemical correlation with splenolide B (7). Complete 1H and 13C NMR assignments for olearin (6), not published hitherto, are also reported.