Seven new xanthones, diaporthones A-G (1-7), together with 13 known analogues, including five mono- (8-14) and six dimeric xanthones (15-20), were obtained from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were established by extensive spectroscopic analyses, including 1D and 2D NMR and high-resolution mass spectrometry (HR-ESIMS). The absolute configurations of 1-7 were clearly identified by X-ray crystallographic analysis and calculation of the ECD Spectra. Compounds 15-20 showed significant anti-inflammatory activity with IC50 values between 6.3 and 8.0 μM. In addition, dimeric xanthones (15-20) showed selective cytotoxicity against T98G cell lines with IC50 values ranging from 19.5 to 78.0 μM.
Keywords: Diaporthe sp.; anti-glioma activity; ascidian-derived fungus; xanthones.