Isolation and Structures of New Cyclomyltaylane and ent-Chamigrane-Type Sesquiterpenoids from the Liverwort Reboulia hemishaerica and Their Biotransformation by the Fungus Aspergillus niger

Abstract

Reboulia hemisphaerica, the thalloid liverwort, contained four new cyclomyltaylane- and two new ent-beta-chamigrane-type sesquiterpenoids of which the absolute stereostructures were established by a combination of two-dimensional NMR spectroscopy, X-ray crystallographic analysis, and the modified Mosher's method. Cyclomyltaylan-5alpha-ol and ent-beta-chamigren-1alpha-ol were biotransformed by the fungus Aspergillus niger to afford new oxygenated matabolites. Their structures were also elucidated in the same manner as described above.