Two new zinniol-related phytotoxins from Alternaria solani

Bioassay-guided purification of the organic crude extract of Alternaria solani resulted in the isolation of three metabolites responsible for causing necrosis on potato leaves. These phytotoxins were identified as 2-(2 '',3 ''-dimethyl-but-1-enyl)-zinniol ( 1), 8-zinniol methyl ether ( 2), and 8-zinniol methyl ether based on their spectroscopic data (IR, MS, H-1 and C-13 NMR). Metabolites 1 and 2 have been identified as new phytotoxins structurally related to zinniol ( 4). Additionally, 5-(3',3'-dimethylallyloxy)-7-methoxy-6-methyl-phthalide and 8-zinniol-2( phenyl)-ethyl ether ( 3) were also isolated during the purification process.