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. unic orne). These fungi are associated with the canker diseases of cypress trees (Cupressus sempervirens) in the Mediterranean area. The structur es of butenolides 1 and 2 were established using spectroscopic and che mical methods in comparison with seiridin [5] and isoseiridin [6], two phytotoxic metabolites produced in higher concentration by the same f ungal species. Necrotic and chlorotic symptoms were produced on cuttin gs of both host and non-host plants by absorption of 100 or 50 mu M so lutions, respectively, of compounds 1 and 2.