Xanthoquinodins from the Endolichenic Fungal Strain Chaetomium elatum

Five new xanthoquinodins, A4–A6 (1–3), B4 (4), and B5 (5), were isolated from the crude extract of the endolichenic fungal strain Chaetomium elatum (No. 63-10-3-1), along with three known xanthoquinodins, A1–A3 (6–8). Their structures were determined by detailed spectroscopic analysis and comparison of the NMR data with those of the closely related compounds previously reported. The absolute configuration of 1 was established by X-ray crystallographic analysis and ECD calculation. The cytotoxic activity of all compounds was tested against HL-60, SMMC-7721, A-549, MCF-7, and SW480 human cancer cell lines.