AB5046A and B, novel chlorosis-inducing substances from Nodulisporium sp.

Novel chlorosis-inducing substances, AB5046A and B, were isolated from the culture broth of a fungal strain. The producing organism, designated AB5046, was identified as a member of Nodulisporium. AB5046A and B were purified by extraction with EtOAc and silica gel chromatography. The structure of AB5046A and B were determined to be 2-butyryl-3,5-dihydroxy-cyclohex-2-ene-1-one and 2-acetyl-3,5-dihydroxy-cyclohex-2-ene-1-one, respectively, by spectroscopic analyses. AB5046A and B induced chlorosis against Japanese barnyard millet in vitro. The chlorosis activity of these compounds was stronger against monocotyledons than dicotyledons.