Yasuto Uchio

Conformational study of the cembranolide diterpene denticulatolide by molecular mechanics method

Abstract The most stable conformation of denticulatolide (1), an ichthyotoxic cembranolide, obtained as a major metabolite of the soft coral, Lobophytum denticulatum, was given by molecular mechanics calculations and it was confirmed by 1H NMR measurement. The geometry of 14-membered carbocycle of 1 was found to be different from that of derivative (2) especially around the juncture part of γ-lactone. The molecular mechanics calculation successfully reproduced the conformational changes between 1 and 2.

Denticulatolide, an ichthyotoxic peroxide-containing cembranolide from the soft coral Lobophytum denticulatum

Abstract Denticulatolide, an ichthyotoxic cembranoid diterpene bearing acetoxy, α-methylene γ-lactone, and cyclic peroxide functions, has been isolated from the soft coral Lobophytum denticulatum. The structure (1) has been determined by spectral and chemical evidence and X-ray crystallographic method.

Constituents of the essential oils from three tetraploid species of Chrysanthemum

Abstract The chemical constituents of the volatile oils from Chrysanthemum indicum, C. yoshinaganthum and C. cuneifolium, three botanically related tetraploid species, are described. By spectroscopic methods, 42 compounds were identified, including 22 monoterpenoids, 17 sesquiterpenoids and 3 acetylenic compounds. The sesquiterpenoids estafiatin (C. yoshinaganthum) and valeranone (C. indicum) have been found for the first time in Chrysanthemum species.

Cembrenene and mayol, two new cembranoid diterpenes from the soft coral sinularia mayi

Two new cembranoid diterpenes, cembrenene (1) and mayol (2), have been isolated from Sinularia mayi Lűttschw, along with the first reported cembrene (3) from marine organism. The structures were determined from spectral data and chemical transformations.

Lobohedleolide and (7Z)-lobohedleolide, new cembranolides from the soft coral lobophytum hedleyi whitelegge

Abstract The structures of lobohedleolide (1) and (7Z)-lobohedleolide (2), two new cembranolides containing the α,β-unsaturated carboxylic acid system isolated from the Japanese soft coral Lobophytum hedleyi Whitelegge, were elucidated from spectral and chemical evidence, and the absolute configuration of (1) was determined by X-ray analysis of its p-bromophenacyl ester (9). Lobohedleolide (1) showed growth inhibition of the in vitro Hella cells.

Labdane diterpene glycosides with 6-deoxy-L-idose from Aster spathulifolius Maxim.

Abstract Three labdane type diterpene glycosides ( 1 , 2 and 3 ) with 6-deoxy-L-idose have been isolated from Aster spathulifolius Maxim. and their structures have been determined on the basis of chemical and spectral data.