Plagiochila Plagiochilins

A continuing investigation of the sesquiterpenoids from liverworts (Plagiochila species) has revealed the presence of more seco-aromadendrane compounds, namely plagiochilines A (652), B (653), C (654), D (655), E (656), and F (657). Plagiochilide (658) has been found in the Swiss species of P. asplenioides but not in the French version. The presumed precursor of these compounds, (-)-bicyclogermacrene (659), has also been identified in the extracts... 

An examination of the sesquiterpenoid constituents of the liverwort Plagiochila semidecurrens has resulted in the isolation of ovalifoliene (=plagiochiline C) (671), hanegokidial (672), and ovalifolienalone (673). A related and wide ranging investigation of other Plagiochila species... 

Further study of the 2,3-secoaromadendrane-type sesquiterpenoids of European Plagiochila species resulted in isolation of plagiochilines C (= ovalifoliene) (48), D (49), E (50) and F (51) 71). The stereostructures of the highly acetylated compounds (49—51) were elucidated mainly by comparison of their H-NMR spectral data with those of plagiochilines A (46) and B (47). Matsuo and his coworkers 209) reported isolation of plagiochiline C whose structure (48) was based on analysis of the NMR spectrum and on chemical degradation (Scheme 7). 

Plagiochila are divided into four chemotypes, an aromadendrane-maaliane-type (Type I), a 2,3-secoaromadendrane-type (Type II), a bibenzyl-type (Type III) and one in which the above constituents are absent (Type IV). Pedinophyllum truncatum is chemically quite similar to Type II of Plagiochila, since it elaborates 2,3-secoaromadendrane-type sesquiterpenes, plagiochiline C (48) and plagiochiline H (53) (2(5). Syzygiella liberata is chemically quite different from Plagiochila and Pedinophyllum species (25a). 

Asakawa, Y., M. Toyota, and T. Tabcemoto La Plagiochiline A et Plagiochiline B, Les Sesquiterpenes du Type Secoaromadendrane de la Mousse, Plagiochila hattoriana. Phytochem. 17, 1794 (1978). 

---