Teruaki Suzuki

Teurilene and thyrsiferyl 23-acetate, meso and remarkably cytotoxic compounds from the marine red alga laurencia obtusa (hudson) lamouroux

Abstract Two new cyclic ethers consisting of squalene carbon skeleton have been isolated from the red alga L. obtusa . The absolute stereostructure of teurilene ( 1 ) was elucidated by x-ray crystallographic method, and the structure of thyrsiferyl 23-acetate ( 2 ) was established from the spectral and chemical evidence.

DIVERSITY OF HALOGENATED SECONDARY METABOLITES IN THE RED ALGA LAURENCIA NIPPONICA (RHODOMELACEAE, CERAMIALES)1,2

Many morphologically similar, but chemically distinct, populations have been found in the marine red alga Laurencia nipponica Yamada (Rhodomelaceae, Ceramiales) growing in Japan. Each chemical type is characterized by a specific end‐product of halogenated secondaly metabolite synthesis: chamigrane‐type sesquiterpenoids such as prepacifenol and halochamigrene epoxide and C15 bromoethers such as laurencin, laureatin, isoprelaurefucin, epilaurallene, and kumausallene. These seven types of secondary metabolite syntheses remained the same in the wild and under various culture conditions. Because bromoethers and terpenoids are probably synthesized by different metabolic pathways, it is virtually certain that different sets of enzymes participate in their synthesis. Prepacifenol‐ and laureatin‐producing populations were selected as representatives of terpenoid and bromoether groups, respectively. F1 tetrasporophytes derived from crosses between reciprocal, female and male gametophytes of prepacifenol‐ and laureatin‐producing strains bore both types of metabolites, suggesting that the genes Producing these enzyme systems are encoded by nuclear genomes. The F1 gametophytes resulting from the reciprocal crosses produced either prepacifenol or laureatin, and the four individuals derived from spore tetrads (a set of tetraspores derived from a single tetrasporangium) produced either prepacifenol or laureatin in a 1:1 ratio, indicating that genes participating in terpenoid synthsis and those participating in bromoether synthesis are on different loci of homologous chromosomes and are segregated at meiosis (tetrasporogenesis). One individual of this interpopulational F1 gamtophyte produced both parental types of metabolite, perhaps indicating the occurrence of a recombination type. Natural hybrid individuals, including such recombination‐type gametophytes, were found in a sympatric locality at which these two chemical types occur. F1 tetrasporophytes derived from crosses between respective prepacifenol‐ and laureatin‐producing strains and their F1 gametohytes produced only parental‐type metabolite‐producing plants. These results indicate that the diverse chemical types can be referred to as races (chemical races).

Laurene, a sesquiterpene hydrocarbon from Laurencia species.

Abstract Laurene, a new sesquiterpene hydrocarbon from Laurencia glandulifera Kutzing and L. nipponica Yamada, is shown to possess structure I. Isolaurene (IV) and epilaurene (XX) have been synthesized.

Intricatetraol, a halogenated triterpene alcohol from the red alga Laurencia intricata ☆

Abstract A unique halogenated triterpenoid with a C 2 symmetry, named as intricatetraol, has been isolated from the red alga Laurencia intricata , and its structure was deduced from chemical, spectral and biogenetic evidence.

(5S,7R,10R)-selin-4(14)-en-5α-ol, a sesquiterpene alcohol from the red alga Laurencia nipponica☆

Abstract A new sesquiterpene alcohol isolated from the red alga Laurencia nipponica has been characterized as (5 S ,7 R ,10 R )-selin-4(14)-en-5α-ol by spectral and chemical methods.

The absolute configuration of cycloeudesmol from the red alga Laurencia nipponica Yamada

Abstract The absolute configuration of cycloeudesmol, isolated from the red alga Laurencia nipponica Yamada and Chondria oppositiclada Dawson, is determined by the crystallographic study.