Kazuya Kurata

Feeding-deterrent bromophenols from Odonthalia corymbifera

Abstract A new diarylmethane-type bromophenol with potent feeding-deterrent activity has been isolated from the red alga Odonthalia corymbifera , and its structure was determined as 2,2′,3-tribromo-4,5,5′,6′-tetrahydroxy-3′- methoxymethyldiphenylmethane on the basis of spectroscopic evidence.

Diterpenoid feeding-deterrents from Laurencia saitoi

Abstract Three new diterpenes and 14 known, brominated and non-brominated diterpenes have been isolated from the red alga Laurencia saitoi collected in ‘Isoyake areas’ in the Sea of Japan. Some of these diterpenes showed significant feeding-deterrent activity against young abalone ( Haliotis discus hannai ) and young sea urchins ( Strongylocentrotus nudus and S. intermedius ), thus suggesting that these metabolites provide a chemical defense against marine herbivorous animals in ‘Isoyake areas’.

Cyclozonarone, a sesquiterpene-substituted benzoquinone derivative from the brown alga Dictyopteris undulata

Abstract A new sesquiterpene-substituted benzoquinone derivative, which we have named cyclozonarone, has been isolated from the brown alga Dictyopteris undulata collected in ‘Isoyake areas’. Its structure was determined on the basis of spectroscopic evidence. Cyclozonarone showed potent feeding-deterrent activity toward young abalones.

Ecklonialactones-C-F from the brown alga Ecklonia stolonifera

Abstract Four new unusual metabolises, ecklonialactone-C and -D with a 14-membered lactone moiety and ecklonialactone-E and -F with a 16-membered one, have been isolated from the brown alga Ecklonia stolonifera . Their structures were deduced from spectral data.

Feeding-deterrent diterpenes from the brown alga Dilophus okamurai

Abstract New diterpenoids with feeding-deterrent activity have been isolated from the brown alga Dilophus okamurai , and their structures determined by spectral and chemical methods.

Spatane-type diterpenes with biological activity from the brown alga Dilophus okamurai

Abstract The neutral methanol extract of the brown alga Dilophus okamurai was found to inhibit the settlement and the metamorphosis of the swimming larvae (veliger) of the abalone Haliotis discus hannai Ino. The active components were identified as spatane-type diterpenes.

Structures of secospatane-type diterpenes with feeding-deterrent activity from the brown alga Dilophus okamurai

Structures of two new diterpenoids with feeding-deterrent activity isolated from the brown alga Dilophus okamurai Dawson have been determined on the basis of spectroscopic evidence.

Venustanol, a brominated labdane diterpene from the red alga Laurencia venusta

Abstract Venustanol, a new brominated diterpene triol closely related to aplysin-20, has been isolated from the red alga Laurencia venusta . Its structure was deduced by spectral methods.

Total Synthesis of Both Enantiomers of Dictyochromenol and their (Z)-Isomers

Total syntheses of both enantiomers of dictyochromenol (1) and its (Z)-stereoisomer (2) were achieved with high enantiomeric purity. The results of this study reveal the relationship between the optical rotation of the resolved 1 enantiomers.

A C26 sterol from the brown alga Eisenia bicyclis

Abstract A new C 26 sterol has been isolated from the brown alga Eisenia bicyclis along with fucosterol, saringosterol and 24-ketocholesterol. Its structure was deduced from spectral data.