Biodegradation pyrethroid insecticides

Paingankar M, Jain M, Deobagkar D (2005) Biodegradation of allethrin, a pyrethroid insecticide, by an Acidomonas sp. Biotechnol Lett 27 1909-1913... 

Casida JE, Ueda K, Gaughan LC, Jao LT, Soderlund DM (1975) Stnicture-biodegradability relationships in pyrethroid insecticides. Arch Environ Contam Toxicol 3 491-500 Cayley GR, Simpson BW (1986) Separation of pyrethroid enantiomers by chiral high-performance liquid chromatography. J Chromatogr A 356 123-134 Chamberlain K, Matsuo N, Kaneko H, Khambay BPS (1998) Pyrethroids. In Chirality in agrochemicals. Wiley, New York... 

Resistance mechanisms associated with changes in toxicokinetics are predominately cases of enhanced metabolic detoxication. With readily biodegradable insecticides such as pyrethroids and carbamates, enhanced detoxication by P450-based monooxygenase is a common resistance mechanism (see Table 4.3). 

Pyrethroids are synthetic analogues of the naturally occurring pyrethrins (isolated from Chrysanthemum sp.) and are popular insecticides for agricultural and domestic uses, with favorable properties like biodegradability and low mammalian toxicity. Prothrin 64 is a member of the furan-based class of p5n ethroids, which also includes the high-volume commercial insecticide resmethrin. Chang et al. recently... 

For example, cycloaddition of carbethoxycarbene (from ethyl diazoacetate as precursor) on XXXIV (R=methyl, Cl, Br) in the presence of various rhodium carboxylates yields cyclopropanecarboxylic acid esters (pyrethroids) that are useful for their insecticidal activity [56] (slightly volatile, biodegradable, non toxic for mammalians). 

Cyclopropanes are occasionally found in Nature, and one class of naturally occurring cyclopropanes, the pyrethroids, are useful insecticides. These compounds are highly toxic to insects but not to mammals, and because they are rapidly biodegraded, cyclopropanes do not persist in the environment. The naturally occurring pyrethroids are found in members of the chrysanthemum family and are formally derived from chrysanthemic acid. Many modified pyrethrins not found in Nature have been made in the laboratory and several are widely used as pesticides. The molecule known as pyrethrin I has the systematic name 2,2-dimethyl-3-(2-methyl-l-propenyl)cyclopropanecarboxylic acid 2-methyl-4-oxo-3-(Z-2,4-dipentadienyl)-2-cyclopenten-1-yl ester. See why the shorthand is used ... 

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. 

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