Taichiro Fujimura

Volatile constituents from marine brown algae of japanese Dictyopteris

cis-3-Butyl-4-vinylcyclopentene, trans-1-[(1Z)-hexenyl]-2-vinylcyclopropane, 4-[(1E)-hexenyl]-cyclopentene, and 6-[(1E)-butenyl]-cyclohepta-1,4-diene were newly identified in the essential oils from fresh Dictyopteris prolifera and D. undulata. On the other hand, the oil of D. divaricata was found to consist mostly of a single sesquiterpene, cubenol (over 95%) instead of the C11-compounds. The growth-locality variation in the chemical compositions of the essential oils in the genus Dictyopteris was discussed.

Cell-destroying sesquiterpenoid from red tide of Gymnodinium nagasakiense

Abstract Epicubenol, α-cadinol and cubenol, were identified as characteristic volatile compounds from both field and cultured red tides of Gymnodinium nagasakiense . They were excreted from the phytoplankton into the media. The amount of cubenol increased from the logarithmic phase to the stationary phase during culture of the plankton, and was shown to cause cell burst of swimming plankton such as G. nagasakiense, Heterosigma akashiwo, Chatonella marina and Chatonella antiqua at 5 ppm.

Dictyopterenes from three Japanese brown algae

Abstract Dictyopterenes A, C′ and D′ found in sexually mature thalli of Scytosiphon lomentaria were not detected in the secretion from the female gametes of S. lomentaria and Colpomenia bullosa. Dictyopterene B [(−)-hormosirene] was secreted at a rate of 2.8 × 10−20 mol cell−1 sec−1 as a sex pheromone from the settled female gametes of both species. Dictyopterenes B and D′ were detected from female gametes of Analipus japonicus. The absolute configurations of dictyopterene B in secretions from the female gametes were found to be (1R,2R) with 66–94% e.e., respectively.

Long-chain aldehyde production in thalli culture of the marine green alga Ulva pertusa

Abstract The essential oil of bacteria- or epiphyte-free thalli culture regenerated from protoplasts of Ulva pertusa was obtained by a simultaneous distillation extraction procedure. The major flavour compounds in the oil of the culture were found to be long chain aldehydes such as (8 Z )-heptadecenal, (8 Z ,11 Z )-heptadecadienal and (8 Z ,11 Z ,14 Z )-heptadecatrienal as in the essential oil of the field fronds. These characteristic aldehydes were shown to be produced by alga enzymes and not by attached bacteria or other epiphytes. A particularly striking observation was that the substrate specificity for the long chain aldehyde-forming activity of the enzymes from the thalli culture was different to those from the field fronds; the best substrate used was oleic acid with linoleic acid an equally effective substrate for the enzymes from thalli culture.

Distribution of long chain aldehyde-forming activity from fatty acids and changes in its activity with growth in marine algae

Long chain aldehyde-forming activity (LCAA) was found to be distributed in a wide range of marine algae including green, brown and red types. The highest LCAA was found in mature fronds of Ulva pertusa. Changes in LCAA with growth were monitored using cultivated fronds of an Enteromorpha species

Production of bioflavor by regeneration from protoplasts of Ulva pertusa (Ulvales, Chlorophyta)

Protoplasts were isolated from thalli of Ulva pertusa using a mixed enzyme solution of 2.0% Cellulase Onozuka R-10, 2.0% Macerozyme R-10, and 2.0% Driselase. Isolated protoplasts regenerated cell walls, developed into thalli, and propagated in large numbers under aeration in the preparative scale-culture system. Typical bioflavor compounds produced from the regenerated plants, as well as from field-collected plants, were found to be long chain aldehydes, which gave a typical seaweed odor. The long chain aldehydes were formed enzymatically from unsaturated fatty acids and released into the culture fluid. A Percoll/mannitol discontinuous density gradient separation of the heterogeneous protoplasts led to a selection of cell lines with high production of bioflavor. The cells that regenerated from protoplasts were immobilized by polymer matrices such as alginate, κ-carrageenan, agarose, and agar. Living cells entrapped in alginate beads in aerated cultures survived best. However, the beads started to breakdown after two months. The immobilized cells demonstrated a higher bioflavor production than did the cultured cells.