Oidiolactone A

Two nematicides, 4-hydroxyphenylacetic acid (4-HPA) (1) and oidiolactone D (2), were isolated from cultures of the fungus Oidiodendron sp., and their structures were identified by spectroscopic analyses. Compound 2 showed nematicidal activities against the root-lesion nematode, Pratylenchus penetrans, and the pine wood nematode, Bursaphelenchus xylophilus. Compound 1 was also active against these two nematodes but to a lesser extent.

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 configurations 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, and 11 were more active as growth inhibitors in a duckweed bioassay (I(50) values of 0.39-0.95 microM) 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.

An efficient, high-yielding strategy has been developed for the asymmetric total synthesis of seven norditerpenoid dilactones known for their diverse biological properties. The three key steps employed to obtain a tricyclic lactone intermediate involved a Morita-Baylis-Hillman reaction, the stereocontrolled construction of a gamma-lactone through bromolactonization, and an efficient catalytic Reformatsky-type reaction. Access to CJ-14,445, LL-Z1271gamma, oidiolactones A, B, C, and D, and nagilactone F was possible from a common intermediate. Structures and stereochemistry were determined by X-ray analysis.