Isolation, identiifcation, derivatization and phytotoxic activity of secondary metabolites produced byCladosporium oxysporum DH14, a locust-associated fungus

摘要

Three main phytotoxic compounds including lunatoic acid A (1), 5Z-7-oxozeaenol (2)and zeaenol (3) were isolated from the fermentation broth ofCladosporium oxysporumDH14, a fungus residing in the locust (Oxya chinensis ) gut. Two additional derivative compounds, compound1a and1b, were synthesized by methylation and chlorination of compound1, respec-tively. The structures of such compounds were identiifed on the basis of spectroscopic analysis and by comparison of the corresponding data to those previously reported in the literature. Compounds1–3 exhibited signiifcantly phytotoxic activities against the radicle growth ofAmaranthus retrolfexus L. with the 50% inhibitory concentrations (IC50 values) of 4.51, 4.80 and 8.16 μg mL–1, respectively, which is comparable to that positive control 2,4-dichlorophenoxyacetic acid (IC50=1.95 μg mL–1). Furthermore, the compound1 showed selective phytotoxic activity with the inhibition rate of less than 22% against the crops ofBrassica rapa L.,Sorghum durra, Brassica campestrisL.,Capsicum annucm and Raphanus sativusL.under the concentration of 100 μg mL–1. Both derivatives of compound1 had moderate phytotoxic activity against the radicle growth ofA. retrolfexusL. The ifndings of our present study suggest that these compounds provide new promising candidates for the potential management strategies of weeds.