Chromone derivatives from the wood-decay fungus Rhizina sp. BCC 12292

A new chromone derivative (1), together with the known oxepino2,3-b]chromones, microsphaeropsones A (2) and B (3), and xanthopinone (4), was isolated from the wood-decay fungus Rhizina sp. BCC 12292. The structure of 1 was elucidated on the basis of NMR spectroscopic and mass spectrometry data. Transformation of 4 into 1 occurred when a solution of 4 in MeOH was treated with p-TsOH or silica gel, which strongly suggested that 1 may be an artifact formed during the processing of the extract. Compound 1 exhibited antimalarial activity with an IC₅₀ of 5.1 μg/ml and cytotoxic activities against NCI-H187 and Vero cell lines with respective IC₅₀ of 6.4 and 1.6 μg/ml.