著者

吉田 達彦 豊田 正夫 菅 由紀子 高岡 茂 橋本 敏弘 浅川 義範

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.38, pp.397-402, 1996-09-02

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Liverworts (Hepaticae) are known to be rich sources of both terpenoids and aromatic compounds with biological activities. The Hepaticae occasionally produce their own peculiar phenolic bis(bibenzyl) derivatives. In the course of our systematic investigation of the chemical constituents of liverworts belonging to the Blasiaceae, we isolated four novel cyclic bis(bibenzyl) dimers, pusilatins A-D (1-4) and two depsides (16, 17) together with nine phenolic compounds (5, 6, 9-15) from Blasia pusilla L. and a novel optically active cyclic bibenzyl-dihydrophenanthrene derivative.(+)-cavicularin (18) from Cavicularia densa Steph. Their structures were characterized by a combination of spectroscopy, X-ray crtstallogarphic analysis and chemical evidences. Further investigation of the phenolic constituents of the thallic liverworts, we isolated a new cyclic bis(bibenzyl) dimer, pusilatin E (8) from Riccardia multifida (L.) S. Gray subsp. decrescens (Steph.) Furuki which was easily derived from riccardin A (7) by coupling reaction using Mn(OAc)_3 ・2H_2O. Previously, we isolated pusilatin D from B. pusilla and proposed the structure (4b) linked by ether C12-O-C1''' bond on the basis of comparison of the ^<13>C NMR data of its acetate with those of the related acethyl compounds. However, the structure (4b) was revised to 4a possessing C10'-O-C11" linkage on the basis of the HMBC analysis. (+)-Cavicularin (18) might be formed by intramolecular phenolic oxidative coupling between 3' and 10' position of riccardin C. On the other hand, riccardin C dimers, pusilatins A-D (1-4) might be biosynthesized by intermolecular coupling between two molecules of riccardin C. These bibenzyl derivatives are significant chemical markers of the Blasiaceae. Pusilatins B (2) and C (3) showed DNA polymerase β inhibitory activity.