Antifouling and Fungicidal Resorcylic Acid Lactones from the Sea Anemone-Derived FungusCochliobolus lunatus

Three new 14-membered resorcylic acid lactones, cochliomycins D–F, 1 – 3, and eight known analogues, 4 – 11, were isolated from the sea anemone-derived fungus Cochliobolus lunatus . Compounds 1 – 4 are diastereomers differing from each other by the absolute configurations of the 4′,5′-diol chiral centers. The absolute configurations of 1 – 4 were established by the CD exciton chirality method and TDDFT ECD calculations. In antifouling assays, 1, 3 – 6, and 6a exhibited potent antifouling activities against the larval settlement of the barnacle Balanus amphitrite at nontoxic concentrations, with EC 50 values ranging from 1.82 to 22.5 μg/mL. Noticeably, fungicide whole-plant assays indicated that 6 showed excellent activity on the Plasmopara viticola preventative test at 6 ppm and concentration-dependent activity on the Phytophthora infestans preventative application at 200, 60, and 20 ppm. Preliminary structure–activity relationships are also discussed.