Chemical Structure of New Marine Diterpenes and Control of Their Biosynthesis

点击翻译按钮获取中文摘要

1. Isolation and structure dertermination of new and antifungal diterpenes of the brown alga, Dictyota dichotomaFrom hydrophobic fractions of the extract of the alga collected at Oshyoro bay, Hokkaido, 22 new diterpenes were isolated and their structures were determined. It was found that the alga produced various bicyclic and tricyclic diterpenes with many kinds of functional group arrangements. All of their skeletons were considered to be derived from prenylated germacratriene. Furthermore, an antifungal substance found in the brown alga was shown to be the known compound dictyol C. It was the first hydroxy hydroazulene exhibiting antifungal activity. The absolute configuration of dilophol was determined by X-ray crystallographic analysis. Nmr analysis and molecular mechanics calculations revealed that the 9 membered ring of dictyofuran T was almost fixed at a stable conformation and dilophol was equilibrated between two stable conformations.2. Biogenesis of the diterpenes found in Dictyota dichotomaBased mainly on the newly determined absolute configuration of dilophol, the biogenetic routes for the various skeletons found in the diterpenes of D. dichotoma were proposed.3. Cytotoxic triterpenes isolated from the red alga, Laurencia obtusaNew triterpene cyclic ethers, teurilene and thyrsiferyl-23-acetate were isolated and their structures were determined. The latter and some of its derivatives showed remarkable cytotoxic property against P388 in vitro cell line.