Biologically Active Tetranorditerpenoids from the Fungus Sclerotinia homoeocarpa Causal Agent of Dollar Spot in Turfgrass

摘要

Nine new tetranorditerpenoid dilactones (>2–10), together with two previously reported norditerpenoids dilactones (>1, 11), and two known putative biosynthetic intermediates oidiolactone-E (>12) and >13 were isolated from an ethyl acetate extract of a culture medium of Sclerotinia homoeocarpa. Structures and absolute configuration of these compounds were determined by spectroscopic methods and confirmed by X-ray crystallographic analysis of representative compounds. Compounds were evaluated for herbicidal, antiplasmodial and cytotoxic activities. Compounds >1, 2, 6, 7, 11 were more active as growth inhibitors in a duckweed bioassay (I50 values of 0.39 - 0.95 µM) than more than half of 26 commercial herbicides previously evaluated using the same bioassay. Some of these compounds exhibited strong antiplasmodial activities as well, but they also had cytotoxic activity thus precluding them as potential antimalarial agents.