Trefolane A, a sesquiterpenoid with a new skeleton from cultures of the basidiomycete Tremella foliacea.
Trefolane A (1), an unprecedented skeleton with a 5/6/4 tricyclic ring system, was isolated from cultures of the basidiomycete Tremella foliacea. The structure was elucidated by means of spectroscopic methods and further confirmed by single crystal X-ray diffraction analysis. A possible biogenesis for trefolane A (1) was also proposed.
Three New Ergot Alkaloids from the Fruiting Bodies of Xylaria nigripes (Kl.) Sacc.
Three new ergot alkaloids, xylanigripones A – C (1 – 3) together with three known compounds, agroclavine (4), 8,9‐didehydro‐10‐hydroxy‐6,8‐dimethylergolin (5), and (6S)‐agroclavine N‐oxide (6) were isolated from the fungus Xylaria nigripes (Kl.) Sacc. Their structures were elucidated by comprehensive spectroscopic analyses and high‐resolution mass spectrometry as well as by comparison with the literature. The absolute configuration was determined by Density Functional Theory (DFT) calculation methods. In addition, all of the compounds were evaluated for bioactivity via a cytotoxicity assay, an acetylcholinesterase inhibition assay and a cholesterol ester transfer protein inhibition assay.
Structure and absolute configuration of a new rearranged chamigrane-type sesquiterpenoid from the sea hare Aplysia sp.
Abstract (6 S ,10 S )-3,10-Dimethyl-7,11-dimethylidenespiro[5,5]undec-2-en-4-one ( 1 ), a new rearranged chamigrane-type sesquiterpenoid with two sp 2 -hybridized carbons in α-positions to the spiro-atom, was isolated from the alcoholic extract of the sea hare Aplysia sp. and its structure and absolute configuration were established by chemical transformations, NMR, EIMS, IR, UV and CD spectroscopy.