title: Isomer-specific comparisons of the hydrolysis of synthetic pyrethroids and their fluorogenic analogues by esterases from the cotton bollworm Helicoverpa armigera.
abstract: The low aqueous solubility and chiral complexity of synthetic pyrethroids, together with large differences between isomers in their insecticidal potency, have hindered the development of meaningful assays of their metabolism and metabolic resistance to them. To overcome these problems, Shan and Hammock (2001) [7] therefore developed fluorogenic and more water-soluble analogues of all the individual isomers of the commonly used Type 2 pyrethroids, cypermethrin and fenvalerate. The analogues have now been used in several studies of esterase-based metabolism and metabolic resistance. Here we test the validity of these analogues by quantitatively comparing their hydrolysis by a battery of 22 heterologously expressed insect esterases with the hydrolysis of the corresponding pyrethroid isomers by these esterases in an HPLC assay recently developed by Teese et al. (2013) [14]. We find a strong, albeit not complete, correlation (r = 0.7) between rates for the two sets of substrates. The three most potent isomers tested were all relatively slowly degraded in both sets of data but three esterases previously associated with pyrethroid resistance in Helicoverpa armigera did not show higher activities for these isomers than did allelic enzymes derived from susceptible H. armigera. Given their amenability to continuous assays at low substrate concentrations in microplate format, and ready detection of product, we endorse the ongoing utility of the analogues in many metabolic studies of pyrethroids.
authors.affiliation: Key laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China; Department of Entomology, College of Plant Protection, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects (Ministry of Agriculture), Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: G
authors.initials: G
authors.lastname: Yuan
authors.affiliation: Research and Development Centre of Biorational Pesticides, Northwest Agriculture and Forestry University, Yangling, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.affiliation: CSIRO Land & Water Flagship, ACT, Australia; School of Biological Sciences, Australian National University, ACT, Australia; Cotton Catchment Communities CRC, Narrabri, NSW, Australia.
authors.forename: C A
authors.initials: CA
authors.lastname: Farnsworth
authors.affiliation: CSIRO Land & Water Flagship, ACT, Australia.
authors.forename: C W
authors.initials: CW
authors.lastname: Coppin
authors.affiliation: CSIRO Land & Water Flagship, ACT, Australia.
authors.forename: A L
authors.initials: AL
authors.lastname: Devonshire
authors.affiliation: CSIRO Land & Water Flagship, ACT, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Scott
authors.affiliation: CSIRO Land & Water Flagship, ACT, Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Russell
authors.affiliation: Department of Entomology, College of Plant Protection, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects (Ministry of Agriculture), Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.affiliation: CSIRO Land & Water Flagship, ACT, Australia. Electronic address: john.oakeshott@csiro.au.
authors.forename: J G
authors.initials: JG
authors.lastname: Oakeshott
mesh_terms: D000818:Animals; D002460:Cell Line; D004950:Esterases / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology*; D007536:Isomerism; D007814:Larva / Q000187:drug effects / Q000201:enzymology; D009036:Moths / Q000187:drug effects* / Q000201:enzymology; D011722:Pyrethrins / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D004950:Esterases
keywords: Esterases; Fluorogenic analogues; Helicoverpa; Pyrethroids