7'-HYDROXYSEIRIDIN AND 7'-HYDROXYISOSEIRIDIN, 2 NEW PHYTOTOXIC DELTA(ALPHA,BETA)-BUTENOLIDES FROM 3 SPECIES OF SEIRIDIUM PATHOGENIC TO CYPRESSES

Two new phytotoxic Delta(alpha,beta)-butenolides, 7'-hydroxyseiridin [1] and 7'-hydroxyisoseiridin [2], were isolated from culture filtrates of three species of Seiridium (S. cardinale, S. cupressi, and S. unicorne). These fungi are associated with the canker diseases of cypress trees (Cupressus sempervirens) in the Mediterranean area. The structures of butenolides 1 and 2 were established using spectroscopic and chemical methods in comparison with seiridin [5] and isoseiridin [6], two phytotoxic metabolites produced in higher concentration by the same fungal species. Necrotic and chlorotic symptoms were produced on cuttings of both host and non-host plants by absorption of 100 or 50 mu M solutions, respectively, of compounds 1 and 2.