Cis-permethrin

Both /nmv-permethrin and bioresmethrin were effectively cleaved by rat serum CES on the other hand, deltamethrin, esfenvalerate, a-cypermethrin, and cis-permethrin were slowly hydrolyzed. These results suggest that PBPK models of some pyrethroids may require the parameter of esterase activity to calculate the concentrations in the intestinal tract, liver, and serum if it is shown that the compounds in the model are appreciably hydrolyzed within these tissues. Such data for human and animal tissues will help to improve the accuracy of extrapolation between species (e.g., rats to humans) and thus enable better predictions of tissue and blood concentrations in humans following exposure to pyrethroids [30]. 

Gaughan, L.C. and Casida, J.E. Degradation of trans- and cis-permethrin on cotton and bean plants, J. Agric. Food Chem., 26(3) 525-528, 1978. 

Dehydrohalogenation.2 K02 in DMF effects dehydrohalogenation of dichloro-vinyl groups to chloroethynyl groups and also of other polychloro groups. This reaction is of considerable interest as a means of detoxifying several polychlorinated pesticides, such as cis-permethrin (1) and DDT (3). 

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]...

Figure 6, Reduction in permethrin concentration in runoff at different locations, (A) cis-permethrin (B) trans-permethrin.

Carene via the key intermediate 213 can alternatively be converted in an essentially one-pot reaction pathway to the optically active y-lactone 215 [397] intended to be a precursor for optically active 1-R-cis-permethrin 216 [398]. 

Although much is already known about the metabolic pathways of fenvalerate in mammals, plants, and soils, its fate in insects had not been much investigated. Colorado potato beetle was the test organism of a metabolism study in which about 20 metabolites were separated and characterized. Seven different elution systems, with one- or two-dimensional TLC or several developments in the same direction using the same mobile phase, were applied to the separation of the metabolites. Some of them are listed in Table 9 (122). Degradation of cis- and rruns-permethrin in flooded soil was studied using carbonyl- C-cis-, carbonyl- C-trans-, and methylene- C-cis-permethrin. The TLC analysis (123) (Table 9) of soil and water extracts showed a faster degradation of tra/ts-permethrin than of CIS-derivative. 

Ross et al. (2006) studied the hydrolytic metabolism of Type 1 pyrethroids (bioresmethrin, IRS fraws-permethrin, and IRS c/s-permethrin) and several Type II pyrethroids (alpha-cypermethrin and deltamethrin) by pure human CEs (hCE-1 and hCE-2), a rabbit CE (rCE), and two rat CEs (Hydrolases A and B). Hydrolysis rates were based on the formation of 3-phenoxybenzyl alcohol (PBAlc) (CAS no. 13826-36-2) for the cis and trans isomers of permethrin. For bioresmethrin, hydrolysis was based on the production of the trans-chrysanthemic acid (CPCA) (CAS no. 10453-89-1). For alpha-cypermethrin and deltamethrin, hydrolysis was based on the formation of c/s-permethrinic acid (DCCA) (CAS no. 57112-16-0) and 3-phenoxybenzyl aldehyde (PBAld CAS no. 39515-51-0), respectively. Human CE-1 and hCE-2 hydrolyzed trans-permethrin 8- and 28-fold more efficiently (based on kcat/Km values) than did c/s-permethrin, respectively. The kinetic parameters (Fmax> for the hydrolysis of trans- and c/s-permethrin, bioresmethrin and alpha-cypermethrin by rat, mouse, and human hepatic microsomes are given in Table 7. The trans- isomer of permethrin is more readily hydrolyzed by rat, mouse and human hepatic microsomal carboxylesterase than c/s-permethrin (13.4, 85.5 and 56.0 times, respectively). However, the lower for hydrolysis of cis-permethrin in human microsomes suggests that there are both stereoisomer and species-specific differences in metabolism kinetics. 

Using the parent compound depletion method, pyrethroid metabolic rate constants (i.e., Umax and K, hast, etc.) for hydroxylation by cytochrome P450 enzymes or hydrolysis by carboxylesterases were developed by Scollon et al. (2009). The sources of the enzymes were rat and human microsomes. The pyrethroids they studied included bifenthrin, S-bioallethrin, bioresmethrin, p-cyfluthrin, cypermethrin, cis-permethrin, and frans-permethrin. The depletion method considers multiple hydroxylations as a single biotransformation at sites on either the acid or alcohol moieties, or on a combination of both. The metabolic pathways (Tables D1-D15 and E1-E15 of Appendices D and E, respectively) require Umax, Am, and values for the individual hydroxylated and hydrolyzed products. It is interesting that only bioresmethrin and cypermethrin per se were found to actually be hydrolyzed. 

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