Sacculatane Diterpenoids from the Liverwort Plagiochila nitens Collected in China

Seven new terpenoids, including six sacculatane diterpenoids
plagiochilarins
A–F (1–6), and one ent-2,3-seco-aromandrane sesquiterpenoid
plagiochilarin H (8) with a 6/7/3/5 tetracyclic scaffold,
alongside three known compounds, were obtained from the Chinese liverwort Plagiochila nitens Inoue. Plagiochilarin B (2) was unpredictably converted to the more stable artifact 7 under acid catalysis through cyclic ether formation. The
reaction mechanism was reasonably deduced and experimentally verified.
The structures of these terpenoids were determined by analysis of
MS and NMR spectroscopic data and single-crystal X-ray diffraction.
The inhibitory effect of all of the isolates was evaluated on the
growth of two C. albicans strains,
wild strain SC5314 and efflux pump-deficient strain DSY654. However,
only plagiochilarin H (8) showed a MIC value of 16 μg/mL
against C. albicans DSY654.