Insect Antifeedant Benzofurans from Species.

In this work, we have studied the benzofurans of (aerial parts and transformed roots), (aerial parts and transformed roots), (aerial parts), and (aerial parts and roots). This work has permitted the isolation of the new benzofurans 10-ethoxy-11-hydroxy-10,11-dihydroeuparin (), (-)-eupachinin A ethyl ether (), 11,15-didehydro-eupachinin A (), 10,12-dihydroxy-11-angelyloxy-10,11-dihydroeuparin (), 2,4-dihydroxy-5-formyl-acetophenone () isolated for the first time as a natural product, 11-angelyloxy-10,11-dihydroeuparin (), and 12-angelyloxyeuparone (), along with several known ones (-). In addition, the incubation of the abundant component, 6-hydroxytremetone (), with the fungus has been studied. Benzofurans in the tremetone series (, , -, , ), the euparin series (, , , -, , ), and the eupachinin-type (, ) were tested for antifeedant effects against the insect . The antifeedant compounds (, , , , ) were further tested for postingestive effects on larvae. The most antifeedant compounds were among the tremetone series, with 3-ethoxy-hydroxy-tremetone () being the strongest antifeedant. Glucosylation of by its biotransformation with gave inactive products. Among the euparin series, the dihydroxyangelate was the most active, followed by euparin (). The eupachinin-type compounds (, ) were both antifeedants. Compounds and showed antifeedant effects without postingestive toxicity to orally dosed larvae. Euparin ( had postingestive toxicity that was enhanced by the synergist piperonyl butoxide.