An eight-ring phlorotannin from the brown alga Himanthalia elongata

From an acetylated fraction of Himanthalia elongata extract, an eight-ring phenolacetate was isolated and its structure elucidated with the aid of field desorption mass spectrometry and other spectroscopic methods.     

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.     

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.     

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.     

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.     

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.     

A phloroglucinol derivative from the brown alga Zonaria tournefortii

The major lipid component of the brown seaweed Zonaria tournefortii was identified as the acylphlorogluconol (all Z)-2′-icosa-5,8,11,14,17-pentae     

Sterols of the brown alga Sargassum fluitans

The sterol composition of the warm-water brown alga Sargassum fluitans Børgesen of the Gulf of Mexico was determined by TLC, GLC and IR measurements. The presence of over ten sterols was suggested, of which four (fucosterol, cholesterol, 24-methylenecholesterol, and trans- 22-dehydrocholesterol) were identified and four (a 24-methylcholesterol, a 24-ethylcholesterol, a 24-methyl-trans-22-dehydrocholestero 1 and a 24-ethyl-trans-22-dehydrocholesterol) were recognized but not definitively identified. Saringosterol and 24-ketocholesterol were not found. The crude sterol mixture from S. fluitans was oxidized by osmium tetroxide to 24-ketocholesterol in poor yield.     

A study of fucoidan from the brown seaweed Chorda filum.

Fucoidan fractions from the brown seaweed Chorda filum were studied using solvolytic desulfation. Methylation analysis and NMR spectroscopy were applied for native and desulfated polysaccharides. Homofucan sulfate from C. filum was shown to contain poly-alpha-(1-->3)-fucopyranoside backbone with a high degree of branching, mainly of alpha-(1-->2)-linked single units. Some fucopyranose residues are sulfated at O-4 (mainly) and O-2 positions. Some alpha-(1-->3)-linked fucose residues were shown by NMR to be 2-O-acetylated. The 1H and 13C NMR spectra of desulfated, deacetylated fucan were completely assigned. The spectral data obtained correspond to a quasiregular polysaccharide structure with a branched hexasaccharide repeating unit. Other fucoidan fractions from C. filum have more complex carbohydrate composition and give rather complex methylation patterns. [formula: see text]     

The plastome of a brown alga,Dictyota dichotoma

Summary Plastids of the brown algaDictyota dichotoma contain a single homogeneous DNA species which bands at a buoyant density of 1.693 g/cm³ in neutral CsCl equilibrium density gradients. The corresponding nuclear DNA has a density of 1.715 g/cm³. The molecular size of the plastid DNA is 123 kbp as calculated by both electron microscopy of spread intact circular molecules and gel electrophoresis following single and double digestions with various restriction enzymes. A restriction map has been constructed using the endonucleases Sal I, Bam HI, and Bgl II which cleave theDictyota plastome into 6, 12, and 17 fragments, respectively. No large repeated regions, as found in chlorophycean andEuglena plastid DNAs, were detected.Dictyota dichotoma is the first member from the chlorophyll c-line of the algal pedigree for which a physical map of plastid DNA has been established. Dedicated to Professor Dr. W. Stubbe on the occasion of his 65th birthday.     

Development of the intercalary meristem in Chorda filum (Laminariales, Phaeophyceae) and other primitive Laminariales

Development of the intercalary meristem in the terete laminarialean species Chorda filum (L.) Stackhouse was studied in culture using light and transmission electron microscopy as well as by tracing elongation and cell divisions in various parts of the sporophyte. Growth of C. filum sporophytes could be classified into three developmental stages: (i) diffuse growth; (ii) basal meristematic growth; and (iii) intercalary meristematic growth. In the diffuse growth stage, elongation and cell division frequency were almost the same in each cell. In the basal meristematic growth stage, elongation and division of cells became localized in the tissues derived from the meristematic initial cell. Cells of the basal meristematic region contained smaller chloroplasts and many small opaque vesicles. In the intercalary meristematic growth stage, there was further elongation and differentiation of cells originating from the meristematic region, and this became more active in adjacent regions below the meristem than in regions above the meristem, causing the relative position of the intercalary meristem to shift towards the tip of the sporophyte. Meristematic cells of C. filum contained well-developed Golgi vesicles around the nucleus (perinuclear Golgi), many secretion vesicles and many small disk-shaped chloroplasts whose thylakoids were not well developed. Sporophytes of three other terete members of Laminariales, Chorda tomentosa Lyngbye, Pseudochorda nagaii (Tokida) Kawai et Kurogi, and Pseudochorda gracilis Kawai et Nabata, show diffuse growth and basal meristematic growth, but no intercalary meristematic growth. This suggests that the common ancestor of the Pseudochordaceae and Chordaceae had basal meristematic growth, and intercalary meristematic growth evolved more recently in C. filum.     

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.     

Two minor diterpenes related to dictyodial A from the brown alga Dictyota crenulata

4β-Hydroxydictyodial A and 18,O-dihydro-4β-hydroxydictyodial A 18-acetate are two minor aldehydic diterpenes in the brown alga Dictyota crenulata. ¹H NMR and lanthanide-induced chemical shift studies indicate that the relative stereochemistry of both compounds is 2R*, 3R*, 4S*, 10S*.     

Chlorierte phlorethole aus Laminaria ochroleuca

After acetylation of the phenolic fraction, monochlorodiphlorethol acetate was detected by MS and a monochlorotriphlorethol C heptaacetate was identified in this alga. Halogenation of triphlorethol C acetate did not yield the natural compound, but instead an isomeric monochloro- and a symmetrical dichloroderivative. The high MW phlorotannins are also halogenated.     

A quinone-hydroquinone couple from the Brown alga Cystoseira stricta

2′E,6′E)-2-(10′,11′-Dihydroxygeranylgeranyl)-6-methylquinol and 2′E,6′E)-2(10′,11′-dihydroxyeranylgeranyl)-6-methyl-1,4-benzoquinone have been isolated from the brown alga Cystoseira stricta. The structures of the new algal metabolites have been elucidated by spectral analysis and chemical degradation.     

Isolation of a new anti-allergic phlorotannin, phlorofucofuroeckol-B, from an edible brown alga, Eisenia arborea

Eisenia arborea is an edible brown alga occasionally used as a folk medicine in gynecopathy in Japan. A new phlorotannin was isolated from the alga during our search for naturally occurring anti-allergic compounds from edible algae guided by the inhibitory effect on histamine release from rat basophile leukemia (RBL)-2H3 cells. The phlorotannin was called "phlorofucofuroeckol-B." Its structure was determined by spectral analysis and chemical conversion. This paper describes the isolation, structure elucidation, and inhibitory effect of phlorofucofuroeckol-B on histamine release.     

Bacterial communities of some brown and red algae from Peter the Great Bay, the Sea of Japan

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with thallus rot, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliphormis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.