Secondary metabolites from the Cordyceps-colonizing fungus Aspergillus versicolor ZJUTE2

Two new polyketides versicolorones A-B (1-2), one new diketopiperazine derivative aspergiamide B methyl ester (3), along with twenty known compounds 4-23, were obtained from the EtOAc extract of the Cordyceps-colonizing fungus Aspergillus versicolor ZJUTE2. The structures of 1-3 were established by detailed interpretation of the spectroscopic data and their absolute configurations were established by comparative analyses of the calculated and experimental ECD spectra. In the in-vitro bioassay, compounds 8 and 21 exhibited significant inhibitory activity against the Escherichia coli beta-glucuronidase (EcGUS) with IC50 values of 54.73 +/- 2.69 and 56.59 +/- 1.77 mu M, respectively.