Identity of sanadaol with β-crenulal,a diterpene from the brown alga Dictyota crenulata

β-Crenulal is a minor constituent of the marine brown alga Dictyota crenulata from Hawaii and is identical with sanadaol isolated from Pachydictyon coriaceum in Japan.     

Novel acyclic diterpenes from the brown alga Cystoseira crinita

Three acyclic diterpenes have been isolated from the brown alga Cystoseira crinita and characterized as (2E,10E)-1,6-dihydroxy-7-methylene-13-keto-3,11,15-trimethylhexadeca-2,10,14-triene, (2E,5E,10E)-1,7-dihydroxy-13-keto-3,7,11,15-tetramethylhexadeca-2,6,10,14-tetracne and (2E, 1OE)-1-hydroxy-6,13-diketo-7-methylene-3,11,15-trimethylhexadeca-2,10,14-triene.     

Diterpenes from Dictyota dichotoma

Two new and two known diterpenes were isolated from Dictyota dichotoma. The structures of the new diterpenes were elucidated from spectral and X-ra     

A novel acylphloroglucinol from the brown alga Zonaria tournefortii

A novel acylphloroglucinol, (5Z,8Z11Z,13E,17Z)-2′-eicosa-15(S)-hydroxy-5,8,11,13,17-pentaenoylphloroglucinol, has been isolated from the brown alga Zonaria tournefortii and its structure proved by spectroscopic and chemical methods.     

Peroxidase activity in the brown alga Laminaria digitata

Cell-free extracts of the brown alga Laminaria digitata catalyse the oxidation of o-dianisidine and of iodide, as well as the formation of iodoamino acids. The enzyme(s) requires hydrogen peroxide for these activities, which are strongly inhibited by cyanide and azide. It is suggested that the activity may be due to a haem-containing peroxidase which, in extracts, is strongly bound, possibly to alginate.     

Two new farnesylacetone derivatives from the brown alga Sargassum micracanthum

From the brown alga, Sargassum micracanthum, two new farnesylacetone derivatives were isolated and their structures elucidated from spectral analyses and chemical correlation to a known farnesylacetone derivative.     

Brominated phlorethols and nonhalogenated phlorotannins from the brown alga Cystophora congesta

The following phlorotannins were isolated from the brown alga Cystophora congesta and characterized as their acetates: phloroglucinol triacetate, bromodiphlorethol pentaacetate, diphlorethol pentaacetate, bromotriphlorethol-A₁-heptaacetate, bromotriphlorethol-A₂-heptaacetate, tetraphlorethol-C-nonaacetate and fucodiphlorethol-D-decaacetate. The substances bromodiphlorethol pentaacetate, bromotriphlorethol-A₁-heptaacetate and bromotriphlorethol-A₂-heptaacetate are the first brominated members of this series to be described. Triphlorethol-A- heptaacetate was isolated previously from C. congesta.     

Trihydroxylated linear diterpenes from the brown alga Bifurcaria bifurcata

Two novel polar diterpenes were isolated from the brown alga Bifurcaria bifurcata collected off the Atlantic coast of Morocco, and their structures established by spectral methods. Both compounds are trihydroxylated acyclic diterpenes derived from 12-hydroxygeranylgeraniol. They were tested in vitro for their cytotoxicity and proved to be active against the NSCLC-N6 cell line. Their absolute configuration at the C-12 position has been determined with a modified Mosher's method [J. Am. Chem. Soc. 113 (1991) 4092] and that of the 12-hydroxygeranylgeraniol (bifurcadiol) has been revised.     

Lipids from the brown alga Cystoseira barbata

Two new diunsaturated lipids, related to palmitic acid, were isolated from the brown alga Cystoseira barbata, one of which is toxic to mice during P388 lymphocytic leukemia tests.     

Three further dolabellane diterpenoids from Dictyota sp.

A brown alga of the genus Dictyota has yielded three new dolabellane diterpenoids the structures of which were elucidated mainly by spectroscopic methods.     

Carbohydrates of the brown seaweed Dictyota dichotoma

The fucose-containing polysaccharides of the brown alga Dictyota dichotoma were extracted with either trichloroacetic acid or HCl to give both water-soluble and water-insoluble materials. The latter had a high proportion (16 to 11%) of protein, and although all the sugars found in the water-soluble extracts were present, the major sugar in these water-insoluble polysaccharides was glucose. The water-soluble material extracted with HCl was a protein-free sulphated heteropolysaccharide. Complete removal of a glucan from the water-soluble extract was achieved by fractional precipitation with ethanol. The recovered glucan-free sulphated polysaccharide, which was rich in glucuronic acid, galactose, fucose and sulphate, showed high anticoagulating activity.     

Lipids and lipid metabolism in the brown alga, Fucus serratus

The lipids of the brown alga Fucus serratus were isolated, identified and quantified. The major acyl lipids were the three glycosylglycerides, diacylgalactosylglycerol, diacyldigalactosylglycerol and diacylsulphoquinovosylglycerol. These represent over 70% of the total acyl lipids. The fatty acid compositions of the major lipids were examined and most showed rather distinctive fatty acid contents. For example, diacylgalactosylglycerol was enriched in n-3 polyunsaturated fatty acids while phosphatidylcholine and phosphatidylethanolamine had very high levels of arachidonate. Phosphatidylglycerol contained the unusual trans-Δ3-hexadecenoic acid. The labelling of lipids and fatty acids from [¹⁴C]acetate was examined and the distribution of label between individual components as a function of the incubation period and in algae collected at different times of the year is reported. Algae collected in the winter incorporated much more radioactivity into non-esterified fatty acids when compared to algae collected in the summer. All algae could label myristate, palmitate, stearate and oleate at high rates. Longer incubation times allowed the labelling of polyunsaturated fatty acids such as linoleic acid.     

Tetraprenyltoluquinols from the brown alga Cystoseira jabukae

The chloroform extract of the brown alga Cystoseira jabukae afforded two new tetraprenyltoluquinols and two tetraprenyltoluquinones. The structures were determined by spectral analysis and chemical correlations. The quinones are possibly artifacts formed by oxidation of the corresponding quinols in the isolation procedure.     

Six diterpenes from Vellozia compacta

Vellozia compacta contains six new diterpenes of the pimarane type. Their structures were deduced on the basis of spectral data and chemical modification.     

Five novel tetraprenylhydroquinols from the brown alga Cystoseira algeriensis

Five novel metabolises of mixed biogenesis have been isolated from the brown alga Cystoseira algeriensis. They are tetraprenylhydroquinols and their structures have been determined by spectral analysis and chemical correlations.     

Phlorotannins with dibenzodioxin structural elements from the brown alga Eisenia arborea

Twenty-one polyhydroxyphenols, which can all be derived from phloroglucinol, were isolated from Canadian Eisenia arborea (Alariaceae). Most of these compounds contain dibenzo[1,4]dioxin elements and also others benzofuran moieties. The basic component is eckol, a hexahydroxyphenoxydibenzo[1,4]dioxin consisting of three phloroglucinol units. Dioxinodehydroeckol is a benzo[1′,4′]benzodioxino[1,4]benzodioxin derived from eckol. 7,7′-Bieckol, 7,9′-bieckol and 7,2″-bieckol are dimers of eckol with biaryl linkages. 8,4·-Dieckol is a dimeric diphenyl ether. 7-Hydroxyeckol contains one and 7,7′-dihydroxy-9,9′-bieckol two additional hydroxyl groups. 3-Phloroeckol and the dehydro derivatives furodehydroeckol A,B and C are composed of four phloroglucinol rings. Halogenated compounds also occur: monobromo- and monoiodophloroglucinol, 4′-bromo- and 4′-iodoeckol as well as one bromo- and one iodophloroeckol.     

New diterpenes from Chamaecyparis pisifera

Three new diterpenes, pisiferin, 15-hydroxyferruginol, and O-methyl pisiferic acid have been isolated and the presence of 12-hydroxyabieta-8,11,13-trien-20-al has been confirmed in studies of the leaves of Chamaecyparis pisifera. The structure of pisiferin, a phenolic diterpene with a new carbon skeleton, has been determined by chemical degradation. The presence of diterpenes of the ferruginol type in the leaves of four varieties of C. pisifera has been examined.