Imidacloprid metabolism

In general, neonicotinoids (except for nitenpyram) are metabolized slowly in plants, and remain mainly as the parent compounds. The definition of crop residues is for the acetamiprid and imidacloprid parent molecule. The definition of crop... 

Soil. The most important metabolic steps were oxidation at the imidazolidine ring, reduction or loss of the nitro group, hydrolysis to 6-chloronicotinic acid and mineralisation. Medium adsorption to soil, imidacloprid and soil metabolites are to be classified as immobile... 

Imidacloprid will be used to illustrate the fate of neonicotinoid insecticides (Figure 8.32). Imidacloprid is reduced (1) and then becomes the triazine derivative (2). It can be hydroxv-lated at the imidazole ring to become themonohydroxylated derivatives (3 and 4). Reduction of parent imidacloprid to the nitroso derivative (5) occurs in some animal species. Imidacloprid is also cleaved to become the nitroiminoimidazololidine (6). Further metabolism involves olefin formation (7), glycine conjugation (8), and others. 

Figure 8.32 Metabolic pathways of imidacloprid in rats. (From Roberts, T.R. and Hutson, D.H., Metabolic Pathways of Agrochemicals, Part 2 Insecticides and Fungicides, The Royal Society of Chemistry, Cambridge, 1998. With permission.)...

Metabolites of pesticidal products in the environment often give useful hints for molecular designs. Studying the metabolic pathway in plants we saw that imidacloprid (9) decomposed to the olefinic metabolite (29) through the hydroxylated intermediate... 

The metabolism of imidacloprid (Figure 5) provides a typical example of the metabolic behavior of chloronicotinoids. In rats, imidacloprid is readily absorbed from the gastrointestinal tract and distributed into the organs within 1 h. Liver and kidney are the target organs. No residues of imidacloprid were... 

Neonicotinoids do not act as a homogenous class of insecticides. Radioligand receptor binding assays revealed two classes of neonicotinoids described here as competitive and non-competitive , respectively, relative to [ H]imidacloprid. Differences in affinity, mode of displacement, number of binding sites and temperature sensitivity suggest that thiamethoxam binds in a way unique among the commercial neonicotinoids. Metabolic transformation is not relevant for its insecticidal effects. 

Like other insecticides, thiamethoxam is transformed in the insect, crop, soil and other compartments to variable degrees to yield products that may not or may be active in their own right. An example for the latter case m the neonicotinoid class is imidacloprid, which is metabolized via hydroxylated intermediates to an olefin product that is more active than the parent compound by one order of magnitude in aphids screens and in receptor binding 20. 21). 

Hoi KK, Daborn PJ, Battlay P, Robin C, Batterham P, O Hair RAJ, Donald WA (2014) Disseeting the insect metabolic machinery using twin ion mass spectrometry a single P450 enzyme metabolizing the insecticide imidacloprid in vivo. Anal Chem 86 3525-3532... 

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