Permethrin is a synthetic insecticide of the pyrethroid family. Pyrethroids are derived from botanical pyrethrins. Approximately 2 million pounds of permethrin are applied annually for agricultural, residential, and public health use in the United States (US EPA, 2009). Like other pyrethroid insecticides, permethrin has a higher insect to mammal ratio of toxicity than organochlorine or organophosphate insecticides (Laffin et al., 2010).
Permethrin biodegradation begins with ester hydrolysis (Maloney et al., 1988), an initial step widespread in pyrethroid metabolism, to produce 3-phenoxybenzyl alcohol and the side chain carboxylate. 3-Phenoxybenzyl alcohol is oxidized to 3-phenoxybenzoate, a major intermediate in pyrethroid insecticide metabolism. It then undergoes angular 1,6 dioxygenation by phenoxybenzoate dioxygenase. The resulting dihydrodiol spontaneously cleaves its ether to produce phenol and 3,4-dihydroxybenzoate (Halden et al., 2000). The other product of the initial esterase hydrolysis, 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate, is mineralized to CO2, but the pathway and organisms that perform these steps are not known (Jordan et al., 1982).
The following is a text-format permethrin pathway map. Organisms that can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (16k) format.
Permethrin Bacillus cereus SM3 Achromobacter sp. SM-2 Pseudomonas fluorescens SM-1 Klebsiella sp. ZD112 Sphingobium sp. JZ-2 Aspergillus niger ZD11 | | | pyrethroid hydrolase | | v 3-Phenoxybenzyl alcohol + 3-(2,2-dichloroethenyl)- | 2,2-dimethylcyclopropanecarboxylate | | | 3-phenoxybenzyl alcohol v A | dehydrogenase | | | from the v v Cypermethrin->3-Phenoxybenzaldehyde CO2 Pathway | | | 3-phenoxybenzaldehyde | dehydrogenase | v 3-Phenoxybenzoate | | | phenoxybenzoate | 1,2-dioxygenase | v 3,4-Dihydroxybenzoate + Phenol | | | | | | | | | | v v to the to the Vanillin Phenol Family Pathway Pathway
Page Author(s): Jeffrey P. Osborne, Manchester CollegeContact Us
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