Chemical and biological characterisation of sapinopyridione, a phytotoxic 3,3,6-trisubstituted-2,4-pyridione produced by Sphaeropsis sapinea, a toxigenic pathogen of native and exotic conifers, and its derivatives

We report the structure of sapinopyridione (1), a phytotoxin produced by Sphaeropsis sapinea causing dieback, canker and shoot blight on cypress trees. The structure-activity relationship was also investigated through the bioassays of three key derivatives.