The use of substituted alkynyl phenoxy derivatives of piperonyl butoxide to control insecticide-resistant pests.

BACKGROUND: Derivatives of piperonyl butoxide with alkynyl side chains were tested in vitro and in vivo against pyrethroid-resistant Meligethes aeneus and imidacloprid-resistant Myzus persicae. RESULTS: Synergists with the alkynyl side chain were more effective inhibitors of P450 activity in vitro than piperonyl butoxide, and demonstrated high levels of synergism in vivo, with up to 290-fold synergism of imidacloprid against imidacloprid-resistant M. persicae. CONCLUSIONS: These 'second-generation' synergists could overcome metabolic resistance in many pest species and possibly enable reduced rates of insecticide application in some cases. © 2016 Society of Chemical Industry.

The interactions between piperonyl butoxide and E4, a resistance-associated esterase from the peach-potato aphid, Myzus persicae Sulzer (Hemiptera: Aphididae).

BACKGROUND: It has been reported previously that piperonyl butoxide (PBO) can inhibit both P450 and esterase activity. Although the method by which PBO combines with cytochrome P450 has been identified, the way in which it acts as an esterase inhibitor has not been established. This paper characterises the interactions between PBO and the resistance-associated esterase in Myzus persicae, E4. RESULTS: After incubation with PBO/analogues, hydrolysis of 1-naphthyl acetate by E4 is increased, but sequestration of azamethiphos is reduced. Rudimentary in silico modelling suggests PBO docks at the lip of the aromatic gorge. CONCLUSIONS: PBO binds with E4 to accelerate small substrates to the active-site triad, while acting as a blockade to larger, insecticidal molecules. Structure-activity studies with analogues of PBO also reveal the essential chemical moieties present in the molecule.

Heterogeneous enantioselective epoxidation of olefins catalysed by unsymmetrical (salen)Mn(III) complexes supported on amorphous or MCM-41 silica through a new triazine-based linker.

High enantioselectivity (ee up to 84%) has been achieved in heterogeneous asymmetric epoxidation using a silica-bound unsymmetrical (salen)-manganese(III) complex; amorphous silica can be used in the same way as MCM-41, showing a positive effect in the catalyst recycling.