Biological activities of natural sesquiterpene lactones and the effect of synthetic sesquiterpene derivatives on insect juvenile hormone biosynthesis

Three natural sesquiterpene lactones have been assayed for their biological activity on locust (Locusta migratoria) nymphs. Since results obtained in vivo pointed to disruptions on juvenile hormone (JH)-regulated physiology, we tested the sesquiterpene lactones and a family of synthetic sesquiterpene derivatives for their ability to disturb the rate of JH biosynthesis by locust corpora allata (CA) in vitro. All the active compounds in vitro share a basic sesquiterpene double-ring structure as well as substituents with different chemical complexities. Compounds that shared an eudesmane base with different oxidation states on C3 and C12 carbon atoms were tested as JH biosynthesis inhibitors. Supplementation of the locust corpora allata culture media with exogenous JH precursors together with data obtained with corpora allata from a moth (Agrotis ipsilon) suggested that epoxidase is a target of the inhibition process.