Bioactive Semisynthetic Dervatives of (S)-(+)-Curcuphenol

Abstract

New semisynthetic sesquiterpene derivatives (3-7, 10), together with two known ones (8-9) were prepared from (S)-(+)- curcuphenol (1), isolated from the Caribbean sponge Didiscus oxeata. The natural sesquiterpenes 1 and (S)-(+)-curcudiol (2), as well as semisynthetic derivatives 3-10, were evaluated against the herbivorous insect species Spodoptera littoralis, Leptinotarsa decemlineata and Rhopalosiphum padi. All compounds had an antifeedant effect on L. decemlineata. With R. padi, a structure-dependent antifeedant response was observed, with 1 being the most active, followed by 4 and 5. Furthermore, compounds 1, 4, 5, 7, 8 and 10 reduced S. littoralis larval weight, with 10 also reducing ingestion by S. littoralis larvae. Of the derivatives studied here, none showed stronger effects (either antifeedant or postingestive) than the parent compound 1. It can, therefore, be concluded that the structure of the side chain and the presence of the phenol ring of curcuphenol are important structural requirements for its insect antifeedant and growth regulation effects.