Synthetic pyrethroids deltamethrin

Anthrahydroquinones have been patented in Japan as bird repeUents (73), and anthraquinone [84-65-1] (qv) is used widely in Europe as a spray to protect growing crops and as a wood dressing. The synthetic pyrethroid deltamethrin [52918-63-5] (27) was evaluated (74), as were other materials, including bendiocarb (20) (75) and 20,25-dia2ocholesterol dihydrochloride [1249-84-9] (Omitrol) (28), a steroid that inhibits embryo development when adsorbed or ingested as a seed treatment of bait com (55,76). 

Taylor, K.S., G.D. Waller, and L.A. Crowder. 1987. Impairment of a classical conditioned response of the honey bee (Apis mellifera L.) by sublethal doses of synthetic pyrethroid insecticides. Apidologie 18 243-252. Theophilidis, G., M. Benaki, and E. Papadopoulu-Mourkidou. 1997. Neurotoxic action of six pyrethroid insecticides on the isolated sciatic nerve of a frog (Rana ridibunda). Comp. Biochem. Physiol. 118C 97-103. Tippe, A. 1987. Evidence for different mechanisms of action of the three pyrethroids, deltamethrin, cypermethrin, and fenvalerate, on the excitation threshold of myelinated nerve. Pestic. Biochem. Physiol. 28 67-74. 

The metabolism of synthetic pyrethroids in plants has been extensively studied and many reviews are available [74, 117, 131]. After application as a formulation to plants, pyrethroid molecules are considered to be dissolved in epicuticular waxes followed by penetration to interior tissues where various chemical and enzymatic reactions proceed. The existing metabolism studies using 14C-labeled pyrethroids clearly show insignificant translocation from treated sites to other parts of plants due to their hydrophobic nature. The reactions in plants can be generally classified into three types photolytic and chemical reactions on plant surface and so-called phase I and II reactions successively proceeding in tissues [60]. Not only the photo-induced cis-trans isomerization for cypermethrin (5) and deltamethrin (6) but also... 

Figure 8.3. Separation of synthetic pyrethroids (0.8 ng of each) on a 25 m OV-101 WCOT capillary column. Peaks 1 = cis-methrin 2 = bioresmethrin 1 + 2 = resmethrin 4 and 5 = phenothrin 6 = cis-permethrin 7 = trans-permethrin 8, 9, 10 and 11 = cypermethrin 12 and 13 = fenvalerate and 14 and 15 = deltamethrin. From [80]...

Synthetic pyrethroids (cypermethrin, deltamethrin, fenvalerate, flumethrin, permethrin) are available in a variety of dosage forms for topical application to... 

Synthetic pyrethroids cypermethrin, deltamethrin, fenvalerate, flumethrin, permethrin. 

Deltamethrin (synthetic pyrethroid) is available as a prepared solution for spot-on application to sheep and is effective against lice, keds, ticks and blowfly (Calliphora, Lucilia) larvae. Cyromazine, a prepared solution for pour-on application to sheep, is effective against blowfly larvae because of the persistence of the drug, it is particularly indicated for the prevention of blowfly strike. Cyromazine protects sheep against blowfly strike (Lucilia cuprina) for up... 

In the last century, the development of organophosphorus, carbamate, and organochloride insecticides was followed by synthetic pyrethroids. As a result, pyrethroids are now used frequently in the domestic milieu. Pyrethroid insecticides are synthetically derived from the molecular structure or sharing the same mechanism of action of natural pyrethrins that have broader spectmm of activity, more stability, and residual activity (persists longer than that of natural pyrethrins) and include the following allethrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, fenvalerate, flumethrin, fluvalinate, tau-fluvalinate, and permethrin (see structure in Fig. 137.2). They are lipophilic compounds and generally of low acute oral toxicity to mammals but are very toxic to aquatic organisms. When synthetic pyrethroids are administered to mammals parenterally, the synthetic pyrethroids are neurotoxic. 

Pyrethroid insecticides are generally classified into one of two large groups on the basis of the central neurotoxic syndrome that they produce [5, 6]. Type I pyrethroids are esters of chrysanthemic acid and an alcohol, having a furan ring and terminal side chain moieties, and absence of a cyano moiety. Allethrin was the first pyrethroid identified in 1949. Allethrin and other pyrethroids such as phenothrin and permethrin with the basic cyclopropane carboxylic ester structure are type I pyrethroids. The insecticidal activity of these synthetic pyrethroids was enhanced further by the addition of a cyano group to give ot-cyano type II pyrethroids such as deltamethrin, fenvalerate, cyfluthrin, cyhalothrin, and lambda-cyhalothrin (Fig. 137.2). 

A wide variety of ectoparasiticides is available, and brand switching is frequent, which is an indication of the problems faced in achieving acceptable parasite control. Concentrated ectoparasiticidal dermal spot-on products are used for the control fleas and ticks and are commonly used on household pets such as dogs and cats. Synthetic pyrethroids such as permethrin and deltamethrin are extremely effective against fleas and other ectoparasiticides in the dog [42], but because of their adverse effects in cats, they are usually contraindicated for this species. 

Pyrethroids. More accurately described as the synthetic pyrethroids, this group of compounds has been used extensively in wood preservation for control of both beetles and termites. Activity, cost and performance characteristics vary depending upon the specific compound but most readily accepted for use in wood preservative formulations are permethrin, cypermethrin, deltamethrin, bifenthrin and cyfluthrin. In terms of activity against wood boring beetles, cyfluthrin is estimated to be 20 times more effective than permethrin, 10 times as effective as cypermethrin and twice as effective as deltamethrin when compared in laboratory evaluative procedures. However, in practice other factors need to be considered, particularly the relative vapour pressures (and therefore evaporative loss) and, in wood in soil contact, the rate of biotransformation by colonising bacteria. The pyrethroids are effective as neurotoxins, and are axonic poisons. 

Mirfazaelian A, Kim K-B, Anand SS, Kim HI, Tomero-Velez R, Bruckner JV, Fisher JW (2006) Development of a physiologically based pharmacokinetic model for deltamethrin in the adult male Sprague-Dawley rat. Toxicol Sci 93 432-442 Miyamoto J (1976) Degradation, metabolism and toxicity of synthetic pyrethroids. Environ Health Perspect 14 15-28... 

Synthetic pyrethroids Acrinathrin, allethrin, biphenthrin, bioresmethrin, cyfluthrin, cypermethrin, deltamethrin, fenvalerate, etofenprox, fenpropathrin, flucythrinate, fluvalinate, lambda-cyhalothrin, permethrin, piperonylbutoxide, tau-fluvalinate... 

Pyrethroids are synthetic esters produced to imitate or improve the activity of biological principles of the pyrethrum plant. They are powerful contact insecticides causing rapid knockdown of treated insects. The pyrethroids are extensively used in controlling insect pests on fruit trees, vegetables, and other field crops in space sprays and contact sprays to kill insects infesting homes, industrial locations, and nonfood processing areas and in protection of warehoused food. These compounds include fenvelerate [51630-58-1], (7), R = Cl flucythrinate [70124-77-5], (1) R = CHF20 allethrin [584-79-2] (8) cyfluthrin [68359-37-5] (9) cypermethrin [52315-07-8] (10) deltamethrin [52918-63-5] (11) permethrin [52645-53-1] (12) and tetramethrin [7696-12-0] (13). 

Asymmetric synthesis by means of a cyandiydrin is an imprvtant process in organic synthesis, because the cyanohydrin can be easily converted into a variety of valuable synthetic intermediates, such as a-hy-droxy ketones, a-hydroxy acids, y-diketones, p-amino alcohols, 4-oxocarboxylic esters, 4 xonitriles, a-amino acids and acyl cyanides. More specifically, the (S)-cyanohydrin of m-phenoxybenzaldehyde is a building block for the synthesis of the insecticide deltamethrin, or (IR)-cis-pyrethroids. ... 

In the middle of the 20th century, the synthetic development of DDT and other chlorinated hydrocarbons (C.H.), increased insecticidal activity well beyond that of most natural products. Problems arose with bioaccumulation of C.H. residues in the food chain, human fat tissue, mother s milk, as well as the development of insecticide resistance. It became obvious there were limitations to synthetic technology as well. The modification of a natural product, for example, from chrysanthemum flowers and their pyrethrum extracts (7) to pyrethroids such as allethrin, resmethrin, permethrin (2), and deltamethrin created a model in which insecticides are created from the skeleton of insecticidally active natural molecules. Thus, the avermectin, abamectin, ivermectin family of pesticides originated from compounds produced by the soil bacterium, Streptomyces avermitilis (5), and the commercially successful chloronicotinyl insecticides, though not derived from nicotine, are chemically related 4). Both pyrethroids and chloronicotinyls are currently used commercially as termiticides. We have previously provided a detailed review of natural products as pesticidal agents for control of the Formosan subterranean termites, Coptotermes formosanus Shiraki (5). 

Synthetic analogs of the pyrethrins, pyrethroids, have been widely produced as insecticides during recent years. The first of these was allethrin, and another common example is fenvalerate (see structural formulas in Figure 4.6). Other examples of insecticidal pyrethroids that have water pollution potential include cypermethrin and deltamethrin. Because of the ways that they are applied and their biodegradabilities, these substances generally are not found to be significant water pollutants. 

Pyrethroids are synthetic analogs of derivatives of chrysanthemic acid, 25.6, naturally occurring in plants of the Chrysanthemum genus. The naturally extracted materials, pyrethrin I and II (25.7, 25.8), have been modified for better activity in compounds such as permethrin, 25.9, and deltamethrin, 25.10. They are toxic to cats and to aquatic life but have otherwise generally low toxicity to mammals and are broken down rapidly in the environment. They are widely used as domestic insecticides. You should note that although a single stereoisomer... 

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