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.