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ABSTRACT: Neonicotinoids with nitro- or cyanoimino substituents are extensively utilized as plant-mobile (systemic) insecticides controlling the piercing-sucking insect pests. This investigation considers structural features of neonicotinoids with trifluoroacetyl pharmacophores, which may confer enhanced hydrophobicity and effectiveness. Fifteen trifluoroacetyl neonicotinoid analogues [=NC(O)CF(3) and =CHC(O)CF(3)] are therefore prepared to evaluate the hydrophobicity index, toxicity to houseflies (Musca domestica), and binding affinity to the Musca nicotinic receptor. The =NC(O)CF(3) and =CHC(O)CF(3) compounds showed a higher hydrophobicity than that of nitro- or cyanoimino analogues. The intrinsic insecticidal activities (defined by intrathoracic injection with a synergist pretreatment) of test compounds were well-correlated to their target site potencies. Although nitro or cyano neonicotinoids were not toxic via the topical application route in the absence of a synergist, trifluoroacetyl analogues exhibited excellent insecticidal activity under the same condition. Accordingly, the increased hydrophobicity of trifluoroacetyl neonicotinoids presumably improves the penetrability of compound into insect integument and insecticidal effectiveness.
Journal of Agricultural and Food Chemistry 04/2010; 58(8):4999-5003. · 2.91 Impact Factor