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We report on the chemical characteristics of the red alga Laurencia japonensis, collected off the coast of Yoshio, Katsuura, Boso Peninsula, Japan. We isolated two new brominated C15-acetogenins in this species, which we name katsuurenyne A (1) and katsuurenyne B (2), along with two already known halogenated terpenes [2,10-dibromo-3-chloro-α-chamigrene (7) and aplysiadiol (8)]. We extensively analysed spectral data (from IR, ESI-MS, 1D-NMR and 2D-NMR) to confirm the structure of these compounds. [ABSTRACT FROM AUTHOR]

Natural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene-containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of omaezallenes were also evaluated. [ABSTRACT FROM AUTHOR]

A molecular phylogenetic study of red algal parasites commonly found in the Northwestern Pacific and the Hawaiian Islands was undertaken. Four species, Benzaitenia yenoshimensis Yendo, Janczewskia hawaiiana Apt, J. morimotoi Tokida, and Ululania stellata Apt et Schlech (Ceramiales), are parasitic on rhodomelacean species belonging to the tribes Chondrieae and Laurencieae. Although Janczewskia and Ululania are classified in the same tribes as their host species, the taxonomic placement of Benzaitenia has been controversial. To infer the phylogenetic positions of these parasites and to clarify the relationships between the parasites and their hosts, phylogenetic analyses of partial nuclear SSU and LSU rRNA genes and the cox1 gene were performed. The SSU rRNA gene analyses clearly show that both Janczewskia species are positioned within the Laurencia s. str. clade with their host species, while Benzaitenia and Ululania are placed in the Chondrieae clade. According to these analyses, J. hawaiiana and U. stellata are not sister to their current hosts; in contrast, B. yenoshimensis and J. morimotoi are closely related to their current hosts. These data suggest that J. hawaiiana and U. stellata have likely evolved from species other than their current hosts and have switched hosts at some point in their evolutionary history. Likelihood ratio tests do not support the monophyly of J. hawaiiana and J. morimotoi, suggesting multiple origins of parasitism within Laurencia s. str. [ABSTRACT FROM AUTHOR]

Cites a study on the characterization of an alga specie Laurencia saitoi Perestenko in Japan. Growth of the alga in channels unexposed to desiccation; Features of the alga's attachment; Effect of environmental conditions on development of the first-order branches of the species.

The article reports that Laurencia yendoi Yamada from several localities in northern Japan is shown to be synonymous with L. nipponica Yamada. Lenticular thickenings, which have not been reported for L. yendoi, can be found in the walls of medullary cells in the lower portions of upright axes of the holotype specimen. This critical character together with other morphological features such as large upright thalli with thick, terete, main axes, irregular radial branching, and absence of projecting surface cells, warrant the treatment of these two entities as being conspecific. The lenticular thickenings are considered to be a useful specific feature.

Summary The red alga Laurencia brongniartii J. Agardh (Rhodomelaceae, Ceramiales) is characterized by: (i) the production of four periaxial cells from each vegetative axial segment; (ii) the presence of two or three corps en cerise per superficial cortical cell and one per trichoblast cell; (iii) the production of a single tetrasporangium‐bearing periaxial (fourth) cell per fertile segment; (iv) a tetrasporangial arrangement that is intermediate between perpendicular and parallel types; (v) procarps produced from the last‐formed (fifth) periaxial cell of the terminal segment of a two‐celled female trichoblast; and (vi) distally positioned spermatangial nuclei, in addition to known features. The production of a single tetrasporangium‐bearing periaxial cell per fertile segment allies this species to Laurencia similis Nam et Saito. [ABSTRACT FROM AUTHOR]

Abstract: The production of labeled brominated metabolites with radioactive 82Br in Laurencia species was investigated as part of a study of the biosynthesis of halogenated metabolites from species belonging to the red algal genus Laurencia (Rhodomelaceae, Ceramiales). Radiobromide [82Br], thin-layer chromatography (TLC), and TLC–autoradioluminography (ARLG) were used. When cultured in artificial seawater medium (ASP12NTA including Na82Br) under 16:8h light:dark (LD) illumination cycles for 24h, each of the strains of Laurencia, Laurencia japonensis Abe et Masuda, Laurencia nipponica Yamada (laurencin-producing race and laureatin-producing race), and Laurencia okamurae Yamada, produced species- (or race-) specific 82Br-containing metabolites. In the case of the laurencin-producing race of L. nipponica, laurencin and deacetyllaurencin were found to be produced in approximately 1:1 ratio, though laurencin is the major metabolite in the wild sample. Furthermore, when cultured in the dark, the production rates of brominated metabolites in Laurencia spp. were found to be diminished. The present study strongly indicates that the use of radiobromine [82Br] in combination with the TLC–ARLG method is an effective approach for investigating the biosynthesis of brominated metabolites in Laurencia. [Copyright &y& Elsevier]

Abstract: During our studies on Malaysian Laurencia species, brominated metabolites, tiomanene, acetylmajapolene B, and acetylmajapolene A were isolated from an unrecorded species collected at Pulau Tioman, Pahang along with known majapolene B and majapolene A. Acetylmajapolene A was a mixture of diastereomers as in the case of majapolene A. Tiomanene may be a plausible precursor for acetylmajapolenes B and A. In addition, three known halogenated sesquiterpenes and two known halogenated C15 acetogenins were found from other two unrecorded species collected at Pulau Karah, Terengganu and Pulau Nyireh, Terengganu, respectively. Some of these halogenated metabolites showed moderate antibacterial activity against some marine bacteria. [Copyright &y& Elsevier]

Abstract: Further investigation of Laurencia species from Japanese waters, which were collected at three locations, yielded brominated metabolites, a labdane- type diterpene and a C15 acetogenin possessing a terminal bromoallene group. Their structures were deduced from analysis of spectroscopic data. [Copyright &y& Elsevier]

The chemical composition of three Laurencia spp., Laurencia sp., L. okamurae and L. saitoi , which were collected from the Seto Inland Sea of Japan, has been examined. Laurencia sp. collected from the coast of Matoba Park, Takehara, Hiroshima Prefecture, contained a brominated chamigrane-type sesquiterpene (1), named matobol, as the main metabolite. The structure of matobol was determined as (+)-(2 R ,3 R ,6 R ,10 S)-2,10-dibromochamigr-7(14)-en-3-ol (1). This is the first time that the optically active 1 has been isolated from Laurencia. On the other hand, L. okamurae from the coast of Ikunoshima Island, Hiroshima Prefecture, produced laurinterol (2) that is a known cyclolaurane-type sesquiterpene characteristic to this species in Japan. L. saitoi from the coast of Matoba Park contained a known bromoallenic C 15 -acetogenin, neolaurallene (3). [Display omitted] • The constitution of Laurencia spp. collected from the Seto Inland Sea of Japan was investigated. • This is the first report of the isolation of (+)-2,10-dibromochamigr-7(14)-en-3-ol (matobol) from Laurencia sp. • Chemical and morphological characteristic of Laurencia sp. are discussed. [ABSTRACT FROM AUTHOR]

We examined the constitution of Laurencia mariannensis collected from the east coast of Tean Island, Thailand. The structure of a new brominated rearranged cyclolaurane-type sesquiterpene, named teanol (1), is reported. This is the first report on biology and chemistry of the Thailand red algal genus Laurencia (Rhodomelaceae, Ceramiales). Image 1 • The constitution of Laurencia mariannensis collected from Thailand was analyzed. • New brominated rearranged cyclolaurane-type sesquiterpene, teanol was isolated. • First report on biology and chemistry of the Thailand red algal genus Laurencia. [ABSTRACT FROM AUTHOR]