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.     

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.     

New bromoterpenes from the red alga Laurencia luzonensis.

Extraction of a sample of Laurencia luzonensis collected off the coast of Kudaka Island, Okinawa, yielded the known sesquiterpenes palisol (1), palisadin B (2), palisadin A (3), pacifigorgiol (4), and aplysistatin (5), together with five new bromosesquiterpenes, isopalisol (6), luzonensol (7), luzonensol acetate (8), luzonensin (9), and (3Z,6E)-1-bromo-2-hydroxy-3,7,11-trimethyldodeca-3,6,10-triene (10). In addition, a new bromoditerpene of unusual structure, 3-bromobarekoxide (11), possessing a seven-membered ring fused to trans-decalin, was isolated.     

Three new sesquiterpenes from the red alga Laurencia perforata

From the lipophilic extract of the red alga Laurencia perforata three new sesquiterpenes, (1S,2S,4S,5S, 6S,8R)-4-hydroxy-2,5,6-trimethyl-11-methylenetricyclo[6.2.1.0(1,6)]undecan-3-one (1, 4-hydroxy-1,8-epi-isotenerone), (3R,4R,4aR,9R)-3,9-dihydroxy-1,4,4a,7-tetramethyl-3,4,4a,5,8,9-hexahydro-2H-benzo[a]cyclohepten-2-one (9-hydroxy-3-epi-perforenone A, 2), and 3-epi-perforenone A (3), were isolated. The structures of all isolates were determined from their spectroscopic data (NMR, MS, IR, UV). Unusual for a species of this algal genus was the apparent absence of halogenated compounds.     

Sulfur-containing polybromoindoles from the Formosan red alga Laurencia brongniartii

Five new sulfur-containing polybromoindoles, 2-methylsulfinyl-3-methylthio-4,5,6-tribromoindole (1), 3-methylsulfinyl-2,4,6-tribromoindole (2), 4,6-dibromo-2,3-di(methylsulfinyl)indole (3), 3,3'-bis(2'-methylsulfinyl-2-methylthio-4,6,4',6'-tetrabromo)indole (4), and 3,3-bis(4,6-dibromo-2-methylsulfinyl)indole (5), as well as seven known sulfur-containing polybromoindoles, 3-methylthio-2,4,6-tribromoindole (6), 3-methylthio-2,4,5,6-tetrabromoindole (7), 4,6-dibromo-2,3-di(methylthio)indole (8), 2,3-di(methylthio)-4,5,6-tribromoindole (9), 4,6-dibromo-2-methylsulfinyl-3-(methylthio)indole (10), 4,6-dibromo-2-(methylthio)indole (11), and 3,3-bis(4,6-dibromo-2-methylthio)indole (12), have been isolated from the Formosan red alga Laurencia brongniartii. The structures were elucidated by extensive spectral analysis, and their cytotoxicity against selected cancer cells was measured in vitro.     

三列凹顶藻中倍半萜成分的研究

目的从三列凹顶藻Laurenciatristicha中寻找具有多样性结构的倍半萜化学成分,供药理活性筛选。方法采用凝胶柱色谱、硅胶柱色谱、重结晶和高效液相色谱等方法进行分离;借助包括一维和二维NMR等波谱方法和X-单晶衍射鉴定化合物的结构;用MTT法对得到的化合物进行细胞毒活性评价。结果分离得到5个倍半萜类化合物,分别鉴定为海兔阿普里素(aplysin,)、海兔阿普里醇(aplysinol,)、去溴海兔阿普里醇(debro-moaplysinol,)、凹顶藻联苯(laurebiphenyl,)、约翰斯顿醇(johnstonol,);在人肿瘤细胞株HCT-8、Bel-7402、BGc-823、A549和HeLa模型上,化合物对所有细胞株均显示毒性,化合物对HeLa细胞显示中等强度的细胞毒活性,其他化合物对所有细胞株均无明显毒性,IC50均大于10.0μg/mL。结论化合物~均为首次从三列凹顶藻中得到,化合物对HeLa细胞具有中等强度的选择性细胞毒活性,化合物对所有细胞株均显示毒性。     

New brominated labdane diterpenes from the red alga Laurencia obtusa

Two labdane type brominated diterpenes (1 and 2) containing unprecedented eight- and seven-membered ether rings have been isolated from the organic extract of the red alga Laurencia obtusa, collected from Mitikas Bay in the Ionean Sea, Greece. The structures of the new natural products, as well as their relative stereochemistry, were established by means of spectral data analysis, including 2D NMR experiments.     

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.     

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。     

A laurane sesquiterpene and rearranged derivatives from the Chinese red alga Laurencia okamurai Yamada

One new laurane sesquiterpenoid, 3beta-hydroxyaplysin (2), and two novel rearranged sesquiterpenes, laurokamurenes A (3) and B (4), together with three known related compounds, 3alpha-hydroxydebromoaplysin (1), debromoaplysin (6), and laurinterol (7), have been isolated from the Chinese red alga Laurencia okamurai. Their structures, including relative stereochemistry, were determined on the basis of detailed interpretation of 2D NMR spectra and comparison with related known compounds.     

三列凹顶藻化学成分研究 Ⅱ

目的：从三列凹顶藻Laurencia tristicha中寻找具有多样性结构的化学成分,供药理活性筛选。方法：采用凝胶柱色谱、硅胶柱色谱、重结晶和高效液相色谱等方法进行分离；借助核磁共振等波谱方法鉴定化合物的结构；用MTT法对得到的化合物进行细胞毒活性评价。结果：分离得到7个化合物,分别鉴定为鉴定为胆甾醇(1),胆甾-5-烯-3β,7α二醇(2),β-谷甾醇(3),叶绿醇(4),玉米黄素(5),对羟基苯甲醛(6),3-吲哚甲醛(7)；在人肿瘤细胞株HCT-8,Bel-7402,BGc-823,A549和HELA模型上,化合物2对所有细胞株均显示毒性,化合物4对HCT-8和HELA细胞显示中等强度的细胞毒活性,其它化合物对所有细胞株均无明显毒性,IC₅₀均大于100 μg·mL^-1。结论：化合物1～7均为首次从三列凹顶藻中得到,化合物2对所有细胞株均显示毒性,化合物4对HCT-8和HELA细胞具有中等强度的选择性细胞毒活性。     

Syntheses of polybrominated indoles from the red alga Laurencia brongniartii and the brittle star Ophiocoma erinaceus

The red alga Laurencia brongniartii and brittle star Ophiocoma erinaceus metabolites 2,3,6-tribromo-1-methylindole (1) and 2,3,5,6-tetrabromo-1-methylindole (2) are easily synthesized selectively from 2,3-dibromo-1-methylindole (5), which in turn is prepared from indole (3) in one continuous sequence in 92% yield. Moreover, 2 can be made from both 1 and 5 in 67% and 65% yields, respectively.     

Diterpenes, sesquiterpenes, and a C15-acetogenin from the marine red alga Laurencia mariannensis

In addition to 10 known compounds (7- 16), one new brominated diterpene, 10-hydroxykahukuene B (1), two new sesquiterpenes, 9-deoxyelatol (2) and isodactyloxene A (3), one new brominated C 15-acetogenin, laurenmariallene (4), and two new naturally occurring halogenated sesquiterpenes (5 and 6) that were previously obtained as intermediates in a biomimetic synthetic study of rhodolaureol and rhodolauradiol have been isolated and identified from the organic extract of the marine red alga Laurencia mariannensis. The structures of these compounds were established by spectroscopic methods. The antibacterial and antifungal activities of new compounds 1-4 were evaluated.     

基根硬毛藻中的倍半萜及其衍生物

目的研究绿藻基根硬毛藻Chaetomorpha basiretorsa的化学成分,从中寻找结构特殊的化合物供活性筛选。方法利用正相和反相柱色谱、Sephadex LH-20柱色谱以及反相HPLC等技术进行分离纯化,借助MS、IR和NMR等方法鉴定结构;通过MTT法对单体化合物进行细胞毒活性筛选。结果从基根硬毛藻中分离鉴定了3个倍半萜类化合物和3个降碳倍半萜类化合物,分别为2-(1,2-二甲基-双环[3.1.0]环己烷-2-基)-5-甲基-苯酚(Ⅰ)、4-溴-2-(1,2-二甲基-双环[3.1.0]环己烷-2-基)-5-甲基-苯酚(Ⅱ)、海兔阿普里素(Ⅲ)、6α-羟基-紫罗-4,7-二烯-3,9-二酮(Ⅳ)、3β-羟基-5α,6α-环氧-β-紫罗烯酮(Ⅴ)、(3R,6R,7E)-3α-羟基-紫罗-4,7-二烯-9-酮(Ⅵ)。结论所有化合物均为首次从本属植物中分得,其中Ⅳ、Ⅴ为首次从绿藻中分离得到,Ⅵ为首次从海洋生物中分离得到。     

New sesquiterpene derivatives from the red alga Laurencia scoparia. Isolation, structure determination, and anthelmintic activity.

Eleven sesquiterpenes (1-11) and one long chain aldehyde (12) have been isolated from the dichloromethane extract of the red alga Laurencia scoparia. Four of them are new natural products. Scopariol (1) is a new natural product with an unusual rearranged chamigrane-type structure. The other three are beta-chamigrenes: isorigidol (2), (+)-3-(Z)-bromomethylidene-10 beta-bromo-beta-chamigrene (3), and (-)-3-(E)-bromomethylidene-10 beta-bromo-beta-chamigrene (4). The in vitro activity of compounds 1-12 against the parasitant stage of Nippostrongylus brasiliensis (L4) has been studied.     

Laurendecumallenes A-B and laurendecumenynes A-B, halogenated nonterpenoid C(15)-acetogenins from the marine red alga Laurencia decumbens

Four new halogenated nonterpenoid C(15)-acetogenins, 4:7,6:13-bisepoxy-9,10-diol-1,12-dibromopentadeca-1,2-diene (1, laurendecumallene A), 4:7,6:12-bisepoxy-9,10-diol-1,13-dibromopentadeca-1,2-diene (2, laurendecumallene B), (3Z)-6:10,7:13-bisepoxy-12-bromo-9-hydroperoxylpentadeca-3-en-1-yne (3, laurendecumenyne A), and (3Z)-6:10,9:13-bisepoxy-12-bromo-7-chloropentadeca-3-en-1-yne (4, laurendecumenyne B), together with one known halogenated C(15)-acetogenin elatenyne (5) were isolated and identified from the organic extract of the marine red alga Laurencia decumbens. Their structures and relative stereochemistry were established by means of spectroscopic analysis including UV, IR, high-resolution electrospray ionization mass spectrometry (HRESIMS), and 1D and 2D NMR techniques. All these metabolites were submitted for the cytotoxic assay against tumor cell line A549 (human lung adenocarcinoma), but all of them were found inactive (IC(50) > 10 microg/mL).     

Bromophenols from the red alga Rhodomela confervoides

Six new bromophenols, 3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)pyrocatechol (1), 2,2',3-tribromo-3',4,4',5-tetrahydroxy-6'-hydroxymethyldiphenylmethane (2), 2,2',3-tribromo-3',4,4',5-tetrahydroxy-6'-ethyloxymethyldiphenylmethane (3), (+/-)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propylaldehyde (4), (+/-)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propylaldehyde dimethyl acetal (5), and 3-bromo-4,5-dihydroxybenzoic acid methyl ester (6), together with eight known bromophenols, 3-bromo-4,5-dihydroxybenzaldehyde (7), 2,3-dibromo-4,5-dihydroxybenzyl alcohol (lanosol, 8), 2,3-dibromo-4,5-dihydroxybenzyl methyl ether (9), 2,3-dibromo-4,5-dihydroxybenzyl ethyl ether (10), 2,3-dibromo-4,5-dihydroxybenzylaldehyde (11), bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (12), 3-bromo-4-(2,3-dibromo-4,5-dihydroxybenzyl)-5-methoxymethylpyrocatechol (13), and 2,2',3,3'-tetrabromo-4,4',5,5'-tetrahydroxydiphenyl methane (14), were isolated from the red alga Rhodomela confervoides. Their structures were elucidated by chemical and spectroscopic methods including IR, HRFABMS, and 1D and 2D NMR techniques.     

Ochtodene derivatives from the red alga Carpopeltis crispata

Red algae are well known as a source of halogenated monoterpenes such as derivatives of ochtodene. From Carpopeltis crispata, we have isolated four new ochtodene derivatives: dibromodichloro-, dibromochloro-, and bromodichlorocyclomonoterpenes. The structures of these monoterpenes were confirmed by NMR and mass spectroscopy and compared with spectral data in the literature.     

New bromoditerpenes from the red alga Sphaerococcus coronopifolius

The organic extract of the red alga Sphaerococcus coronopifolius, collected along the Atlantic coast of Morocco, was tested for biological activities and exhibited antibiotic and antimalarial activities. Two new bromoditerpenes have been isolated from S. coronopifolius, sphaerolabdadiene-3,14-diol (1) and bromosphaerone (2), along with the known compounds 12S-hydroxybromosphaerodiol (3) and sphaerococcenol A (4). Bromosphaerone and 12S-hydroxybromosphaerodiol showed antibacterial activity against the Gram-positive bacterium species Staphylococcus aureus with a minimum inhibitory concentration of 0.104 and 0.146 microM, respectively. Sphaerococcenol A (4) was responsible for the antimalarial activity of the extract, against the chloroquine resistant Plasmodium falsciparum FCB1 strains with an IC(50) of 1 microM. Their structures have been assigned using 1 and 2 D NMR and HRMS.     

Bromophenol derivatives from the red alga Rhodomela confervoides

Eight new bromophenol derivatives, 2,3-dibromo-4,5-dihydroxybenzyl methyl sulfoxide (1), 4-(2,3-dibromo-4,5-dihydroxyphenyl)-3-butene-2-one (2), 2-(3-bromo-5-hydroxy-4-methoxyphenyl)-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid (3), 2-(3-bromo-5-hydroxy-4-methoxyphenyl)-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid methyl ester (4), 2-phenyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid (5), 4'-methoxy-2',3',3'-tribromo-4',5',5'-trihydroxydiphenylacetic acid (6), and 3-bromo-5-hydroxy-4-methoxyphenylacetic acid (7) and its methyl ester (8), together with a known bromophenol, 3-bromo-5-hydroxy-4-methoxybenzoic acid (9), were isolated from the red alga Rhodomela confervoides. Their structures were elucidated by spectroscopic methods including IR, EIMS, FABMS, ESIMS, HRFABMS, HRESIMS, 1D and 2D NMR, and single-crystal X-ray structure analysis. Compounds 1-4, 8, and 9 were found inactive against several human cancer cell lines and microorganisms.