Insecticidal properties of annonaceous acetogenins and their analogues. Interaction with lipid membranes.

The interactions were studied by FTIR and DSC of the terminal lactone of annonaceous acetogenins (ACGs) and synthetic analogues, such as THF, with POPC bilayers, as well as the toxic effect produced by these compounds on Spodoptera frugiperda larvae. The aim of this work was to find a relationship between ACG insecticidal properties and the specific sites of interaction with lipid membranes. ACGs interact to different extents with the phosphate of lipid membranes and differences in the antisymmetric stretching of the phosphate groups were found in the presence of water that indicate water loss and further hydrogen bonding. The ACG tested produced more than 70% larval mortality. Rolliniastatin-1 (3) proved to have the most toxic effects (100%) on early larval instars when incorporated in the larval diet at a dose of 100 mu g per g of diet. Additionally, it produced a significant decrease in growth rate (GR) and consumption index (Cl), and reduced the efficiency with which larvae converted ingested food into biomass (ECI). The destabilization that occurs in the membrane due to dehydration around the phosphate groups caused by interaction with ACGs and their synthetic analogues would account for ACGs' insecticidal action.