Acetamiprid

Acetamiprid is an organic compound with the chemical formula C10H11ClN4. It is an odorless neonicotinoid insecticide produced under the trade names Assail, and Chipco by Aventis CropSciences. It is systemic and intended to control sucking insects (Lepidoptera, Thysanoptera, Hemiptera, mainly aphids) on crops such as leafy vegetables, citrus fruits, pome fruits, grapes, cotton, cole crops, and ornamental plants. It is also a key pesticide in commercial cherry farming due to its effectiveness against the larvae of the cherry fruit fly. Acetamiprid is an organic compound with the chemical formula C10H11ClN4. It is an odorless neonicotinoid insecticide produced under the trade names Assail, and Chipco by Aventis CropSciences. It is systemic and intended to control sucking insects (Lepidoptera, Thysanoptera, Hemiptera, mainly aphids) on crops such as leafy vegetables, citrus fruits, pome fruits, grapes, cotton, cole crops, and ornamental plants. It is also a key pesticide in commercial cherry farming due to its effectiveness against the larvae of the cherry fruit fly. Acetamiprid is an insecticide belonging to the chloropyridinyl neonicotinoids, this family of insecticides was introduced in the early 1990s. This compound is an insecticide that is introduced for controlling pests, but also for domestic use to control fleas on cats and dogs. Acetamiprid is an alpha-Chloro-N-heteroaromatic compound. It is a neonicotinoid with a chloropyridinyl group and it is comparable to other neonicotinoids such as imidacloprid, nitenpyram and thiacloprid. These substances all have a 6-chloro-3-pyridine methyl group but differ in the nitroguanidine, nitromethylene, or cyanoamidine substituent on an acyclic or cyclic moiety. There are two isomeric forms in acetamiprid with E and Z-configurations of the cyanoimino group. There are also a variety of stable conformers due to the rotation of single bonds in the N-pyridylmethylamino group. The E-conformer is more stable than the Z-conformer and assumed to be the active form. In solution, two different E-conformers exist which slowly change into each other. Acetamiprid is a nicotine-like substance and reacts to the body in a similar way as nicotine. Nicotine is a natural insecticide of which many man-made insecticides are derivatives. Acetamiprid is a nicotinic agonist that reacts with nicotinic acetylcholine receptors (nACh-R). These receptors are located in the post-synaptic dendrites of all neurons in the brain, spinal cord, ganglia and muscular junctions. The activation of the nACh-R receptors causes hyperactivity and muscle spasms, and eventually death. Acetamiprid is highly toxic to insects, but less to mammals. This is probably due to a different form of receptor in vertebrates. The metabolism of acetamiprid has been primarily studied in plants and soil. However, a recent study (2005) focussed on the metabolism of acetamiprid in honey bees. The honey bees in this study were fed a sucrose solution that contained acetamiprid. Seven different metabolites were discovered, of which two could not be identified. The five most abundant of these metabolites were found in the abdomen of the bee. Within the first hour of ingestion, acetamiprid concentrations were highest in tissues with a high nicotinic acetylcholine receptor density such as the abdomen, thorax and head. Acetamiprid was rapidly distributed throughout the bee’s body, but also rapidly metabolised into the seven compounds. The substance is not just broken down in the gut, but in the entire body of the bee. This is mainly done by Type I enzymes such as mixed function oxidases. These enzymes use O2 to catalyze a reaction and convert acetamiprid into more polar metabolites. This makes it easier to excrete the compounds because the compounds become more hydrophilic. Phase I enzymes form the first step in metabolizing the compound. Phase I metabolites can be bioactive. Three metabolic pathways exist, based on the kinetics of the metabolites that were found. The first pathway starts with the oxidative cleavage of the nitromethylene bond of acetamiprid. This is followed by another oxidation that forms 6-chloronicotinic acid. 6-Chloronicotinic acid is then transformed in one of the unidentified compounds, with an increased polarity. The second possible pathway is based on N-demethylation reactions, followed by oxidation of the nitromethylene bond of the intermediates. This will also result in 6-chloronicotinic acid. The last pathway consists of the oxidative cleavage of the cyanamine group. In this reaction a 1-3 ketone derivative is formed. This compound will undergo N-deacetylation which forms a 1-4 ketone derivative. This compound is transformed by oxidative cleavage into 6-chloropicolyl alcohol. From here, the compound can be metabolized in two different ways: either it is oxidized into 6-chloronicotinic acid or it is converted into a glycoconjugate derivative. The latter is probably in favour of the oxidization.