Shinichi Sakemi

Venustatriol. A new, anti-viral, triterpene tetracyclic ether from Laurencia venusta

Abstract Venustatriol, a new tetracyclic ether derived from squalene, which has anti-viral activity, has been isolated from the red alga Laurencia venusta . Its structure and absolute configuration were determined by X-ray using the absolute structure parameter x. By comparison of their spectral properties, the absolute configuration of its congener, thyrsiferol, was deduced.

Batzellines A, B, and C. Novel pyrroloquinoline alkaloids from the sponge Batzella Sp.

Three highly functionalized pyrroloquinoline alkaloids, batzelline A ( 1 ), B ( 2 ), and C ( 3 ) were isolated from the deep water Bahamas sponge Batzella sp. The structure of 1 was determined by X-ray and those of 2 and 3 deduced by comparison of their spectral data with that of 1 and by chemical transformations.

Antitumor cyclic peroxides from the sponge plakortis lita

Abstract Four new cyclic peroxides (5–8) along with known chondrillin (4) have been isolated as antitumor constituents of the sponge Plakortis lita. These are methyl-(3S*, 6S*)-3, 6-epidioxy- 6-methoxyoctadec-4-enoate (5), methyl( 3S*, 6S*, 16E)-3, 6-epidoxy- 6-methoxyoctadeca-4,16-dienoate (6), methyl( 3S*, 6S*, 14E, 16E)- 3, 6-epidioxy-6-methoxyoctadeca-4, 14, 16-trienoate (7), and methyl-( 3S*, 6S*, 16E, 18E)-3, 6-epidioxy-6-methoxyeicosa-4 ,16 ,18- trinoate (8). All of them are epimeric to 4 and exhibit higher antitumor potency than 4.

Environmental studies on natural halogen compounds. I Estimation of biomass of the acorn wormPtychodera flava Eschscholtz (Hemichordata: Enteropneusta) and excretion rate of metabolites at Kattore Bay, Kohama Island, Okinawa

In order to study the environmental significance of the acorn wormPtychodera flava, which excretes a copious amount of halogenated metabolites, the biomass and the excretion rate were estimated at Kattore Bay, Kohama Island, Okinawa. The habitat, which extends over 1 km2, could be divided into two areas: zone A, 3.0 × 105m2, density 95.6/m2; and zone B, 7.2 × 105 m2, density 48.8/m2, according to the densities. The total population was estimated to be 6.4 × 107 ± 2.0 × 107 individuals or 93.0 ± 28.9 tons. These worms daily excrete about 480 tons of fecal sand which was estimated to contain 43 kg of the material extractable with organic solvents. The material contained halogenated metabolites which showed antimicrobial activity.

Isolation of free deoxyribonucleosides and their bases from the acorn worm Ptychodera flava

Abstract 1. 1. An aqueous extract of the acorn worm Ptychodera flava was investigated for hydrophilic constituents. 2. 2. Isolated from the extract were four deoxyribonucleasides (deoxyguanosine, deoxyinosine, deoxyuridine, and deoxythymidine) and three bases (hypoxanthine, uracil, and thymine). 3. 3. Free deoxyribonucleosides, especially deoxyinosine and deoxyuridine have rarely been isolated from marine invertebrates.