Secondary Metabolites from Aspergillus sparsus NBERC_28952 and Their Herbicidal Activities.

Fungi have been used in the production of a wide range of biologically active metabolites, including potent herbicides. In the search for pesticides of natural origin, Aspergillus sparsus NBERC_28952, a fungal strain with herbicidal activity, was obtained. Chemical study of secondary metabolites from NBERC_28952 resulted in the isolation of three new asperugin analogues, named Aspersparin A-C ( 2 - 4 ), and a new azaphilone derivative, named Aspersparin D ( 5 ), together with two known compounds, Asperugin B ( 1 ) and sydonic acid ( 6 ). The structures of these compounds were elucidated based on extensive spectroscopic data and single-crystal X-ray diffraction analysis. All of the isolated compounds were evaluated for their herbicidal activities on seedlings of Echinochloa crusgalli and Amaranthus retroflexus through Petri dish bioassays. Among them, compounds 5 and 6 exhibited moderate inhibitory activities against the growth of the roots and shoots of E . crusgalli seedlings in a dose-dependent manner, while 6 showed obvious inhibitory effect on seedlings of A . retroflexus, with an inhibitory rate of 78.34% at a concentration of 200 μg/mL. These herbicidal metabolites represent a new source of compounds to control weeds.