Putaminoxins B and C from Phoma putaminum

A phytotoxic macrolide and a hexaketide, putaminoxins B and C, respectively, were isolated together with putaminoxin, the main phytotoxin, from liquid culture filtrates of Phoma putaminum, the causal agent of leaf necrosis of Erigeron annuus, a common weed of fields and pastures. Putaminoxins B and C were characterized, using spectroscopic methods, as a new disubstituted nonenolide and a new disubstituted cyclononendione, respectively. Assayed on leaves of weedy and cultivated host plants, putaminoxins C showed toxic effects similar to those produced by putaminoxin.