No abstract

Eleven eremophilanolides, 1-3 and 6-13, and two eremophilanes, 24 and 25, were isolated from Senecio candidans and S. magellanicus from the Magallanes Region (Chile). Compounds 2, 3, 9, and 10 have not been previously reported as natural products. Their structures were established by NMR spectroscopic analysis and chemical transformations. The X-ray analysis of compounds 11, 13, and 17 were also performed. Different semisynthetic analogs from eremophilanolide 11 were generated to carry out a structure-activity relationship study. Their possible plant defensive role was tested against herbivorous insects (Spodoptera littoralis, Rhopalosiphum padi, and Myzus persicae) and plants (Lactuca sativa). Additionally, their effects on insect (Sf9) and mammalian (CHO) cell lines were tested.

The furanoeremophilanes 6β-angeloyloxy-1, 10-dehydrofuranoeremophilan-9-one (1), 6β- hydroxy-1, 10-dehydrofuranoeremophilan-9-one (2) and 6β-propionyloxy-1, 10-dehydrofuranoeremophilan- 9-one (3) were isolated from Senecio otites, their structures elucidated by spectral analyses, and their insecticidal and phytotoxic properties evaluated. Compounds 1-3 proved to be effective aphid antifeedants against Myzus persicae and Rhopalosiphum padi and had postingestive negative effects on Spodoptera littoralis larvae. These compounds did not have any phytotoxic effects on Lactuca sativa.