Clerodane diterpenes from Baccharis sagittalis: insect antifeedant activity.

Two clerodane-type diterpene glycosides esters, which were studied as peracetyl derivatives, together with the known diterpene marrubiagenine, were isolated from the aerial part of Baccharis sagittalis (Less). Their structures were established by spectroscopic methods. Antifeedant activity toward Tenebrio molitor larvae of the isolated compounds along with six other diterpenes was evaluated and some structure-antifeedant bioactivity relationships are reported.