Essential insecticidal activity

Although a lipoid-soluble group characterizes many contact insecticides, simple oil-solubility of a compound is not always a criterion of activity. Busvine (14) tested a series of DDT analogs and found that solubility in oil was not essential to activity. Kirkwood... 

Yang, Y.C., Lee, S.H., Clark, J.M. and Ahn, Y.J. (2003a) Insecticidal activity of plant essential oils against Pediculus humanus capitis (Anoplura Pediculidae). Journal of Medical Entomology 41,699-704. 

It is known that the (S)-forms are the essential stereoisomers for the insecticidal activities of both alcohols (4,5). Chemico-enzymatic processes are also reported in this article on the preparation of the optically active pyrethroid insecticides having the (S)-isomers of the two alcohols. Processes were developed that use enantioselective hydrolysis with a lipase. 

Nicotine (1) is an old insecticide which acts on the postsynaptic nAChR. This botanic insecticide t pears to have interested a few chemists as a lead for a new insecticide. More than 30 years ago Yamamoto recognized the 3-pyridylmethyl amine residue as the essential part for the insecticidal activity by referring to the model of nAChR agonists by Beers and Reich [4], and prepared quite a number of 3-pyridylmethylamines [5,6]. Nicotine, being an acetylcholine mimic, can bind to the receptor by two elements (a) a... 

Repellent activity, which also respected as insecticidal activity, of T. vulgare was reported by Schearer [222]. The steam distillate of fresh leaves and flowers of tansy was found to be strongly repellent to Colorado potato beetles, Leptinotarsa decemlineata. It seems that this activity is related with essential oils. 

It has been shown for avermectin B that the hydroxyl group at C-5 and a disaccharide moiety are essential for antiparasitic, mitocidal and selective insecticidal activities. Chemical modification of the macrolide-type avermectins resulted in ivermectin which was commercialized to be used in agriculture and animal health care as well as in human medicine. 

The structure-insecticidal activity relationships of picrotoxinin analogs and related compounds have been studied by several researchers (3,16), who noted that the bridged bicyclic lactone skelton and the trans-isopropenyl or isopropyl group are essential for insecticidal activity. Structure-activity relationships of cyclodiene insecticides and BHC have also been thoroughly discussed (17-19). However, these discussions were published before the nature of the biological target site(s) for cyclodienes was known. 

Numerous monoterpenes were identified in the essential oil of the rhizomes of Z. cassumunar [279]. From the hexane extract of the rhizomes of Z. cassumunar, thirteen aromatic compounds 309,310, 312, 317-324, 326 and 327 were isolated [280-282]. The structures of these compounds were determined on the basis of their spectroscopic data and by syntheses. The crystal structures of cyclohexene derivative 312 and quinone 324 were determined by X-ray diffraction analysis [280]. Evaluation of the biological activity of these compounds revealed that compound 317 possessed smooth muscle relaxant activity ( guinea-pig ileum and tracheal chain) [283].The mechanism of bronchodilator activity of 317 was found to be similar to those of aminophylline and papaverine [284]. Compound 317 also exhibited uterine relaxant effect and shared a similar mechanism of action with papaverine [285]. Anti-inflammatory activity of 309, 312, 317-319, 326 and 327 was evaluated using the carragenin-induced rat paw edema model and compound 317 was reported to possess the strongest inhibitory activity on the edema formation [286]. Compounds 322 and 323 exhibited insecticidal activity towards neonate larvae ofSpodoptera littoral is [266]. 

The last section shows the effect of substituents (Rj, R2) on the aliphatic amide moiety. As for the aliphatic side chain, it was found that the alpha-branched alkyl side chain was essential for stabilizing the diamide structure. In the case of non-branched alkyl, the diamide derivatives tend to decompose to the corresponding phfhalimides. A variety of substituents were examined to improve the activity. As shown in Table I, the introduction of a heteroatom or a functional group increased the insecticidal activity especially a sulfur atom within the alkyl side chain markedly increased the activity. This sulfonylalkylamine is also novel as an amine residue in pesticide chemistry. In summary, flubendiamide has unique substituents as essential parts of the structure in three adjacent positions on the benzene ring, which characterizes the chemical structare of flubendiamide as totally novel. 

In reality, pesticides of botanical origin have been used for centuries to protect crops and stored products and to repel pests from human habitations. Among the most well known are pyrethrum, neem, rotenone, nicotine and plant essential oils, although more than 2,000 plant species have been found to possess insecticidal activity [3-4]. However, while most botanical pesticides are known solely for their insecticidal activity, plant essential oils are also known for their uses as fragrances, flavorings, condiments or spices, and many are also considered to have medicinal uses. Given this widespread use, numerous plant essential oils are already widely available and their chemistry is generally well-understood. 

These examples indicate the complexity of insect nAChRs, which is difficult to understand. The considerable diversity of potential subunit combinations probably accounts for the multiplicity of distinctive pharmacological profiles in insect nAChRs. In that context, electrophysiology will play an essential role in determining the significance of certain subunit combinations in the MoA of neonicotinoid and further insecticidally active ligands. 

Chaubey, M.K. 2007. Insecticidal activity of Trachyspermum ammi (UmbeUiferae), Anethum grave-olens (UmbeUiferae) and Nigella sativa (Ranunculaceae) essential oils against stoied-product beetle Tribolium castaneum Herbst (Coleoptera Tenebrionidae). Afr. J. Agric. Res. 2 596-600. 

Derwich, E., Z. Benziane, and A. Boukir. 2009. Chemical compositions and insecticidal activity of essential oils of three plants Artemisia sp. (A. herba-alba, A. absinthium and A. Pontica (Morocco). Electron. J. Environ. Agric. Food Chem., 8 1202-1211. 

Ayvaz, A., 0. Sagdic, S. Karaborklu, and 1. Ozturk, 2010. Insecticidal activity of the essential oils from different plants against three stored-prodnct insects, 70 21. 

Kim, S.-L, J.-Y. Roh, D.-H. Kim, H.-S. Lee, and Y.-J. Ahn, 2003b. Insecticidal activities of aromatic plant extracts and essential oils against Sitophilus oryzae and Callosobruchus chinensis. <... 

Negahban, M., S. Moharramipour, and F. Se dkon, 2006. Chemical composition and insecticidal activity of Artemisia scoparia essential oil against three coleopteran stored-product insects. 

Don-Pedro, K. N., 1966. Fumigant toxicity is the major route of insecticidal activity of citrus peel essential oils. 46 71-78. 

Liu ZL, Chu SS, Jiang GH (2011) Insecticidal activity and composition of essential oil of Ostericum sieboldii (Apiaceae) against Sitophilus zeamais and Tribolium castaneum. Rec Nat Prod 5 74-81... 

Enan EE (2001) Insecticidal activity of essential oils octopaminergic sites of action. Comp Biochem Physiol 130 325-327... 

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