Butyrolactones and acid esters from plant rhizosphere soil-derived Aspergillus sp. TW01-p-15

The fungus Aspergillus sp. TW01-p-15 was isolated from rhizosphere soil of Pteris cretica L. var. nervosa in Xitoushan, Taiwan Province of China. From the ethyl acetate extract of the fungus, five new compounds including two new butyrolactones named 2-carbonic acid-ester- butyrolactone V (1), versicolactone H (2), one new butyrolactone derivative 2-hydroxy-1,3-bis(4-hydroxyphenyl) propan-1-one (3), two new acid esters named (Z)-6-methoxy-3-methyl-6-oxohex-2-enoic acid (4) and (E)-6-methoxy-3-methyl-6-oxohex-2-enoic acid (5), together with nine known compounds were isolated. Their structures were elucidated by diverse spectroscopic analysis including high-resolution ESI-MS, one- and two-dimensional NMR spectroscopy and time-dependent density functional theory electronic circular dichroism (TDDFT ECD) calculations. In the in vitro activity experiment, compounds 3 and 13 showed significant activity against Pseudomonas aeruginosa. This result was further supported by molecular docking.