Nimbya alternantherae is a leaf spot fungus isolated from Alternanthera philoxeroides.It could produce phytotoxin to Alternanthera philoxeroides in several kinds of liquid media,especially in modified Fries.The filtrate of the pathogen was chromatographed on a DM-130 colophony column eluting with methanol,and evaporation of the solvent gave a brown mush.The crude product was then extracted with ethyl acetate.The toxin could be purified as white needles by re-crystallizing from benzene and acetone（volume ratio is 1∶1） and silica gel chromatograph.The results of elemental analysis,MS,IR and NMR indicate that molecular weight of the toxin was 240,formula was C11H12O6,and its chemical name was 2-acetyl-3,4-dihydroxy-5-methoxyphenyl-acetic acid（Vulculic acid）.
