Metabolism of the Pyrethroid Insecticide Cypermethrin in Cabbages

Abstract

Metabolism in cabbage plants of (1R)-cis-and (1R)-traps-isomers of Cypermethrin [(RS)-a-cyano-3-phenoxybenzyl(1RS)-cis, trans-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate] was investigated with 14C preparations labeled separately in the benzylphenyl ring and cyclopropyl ring. The half-life of disappearance was about 4-5 days and 7-8 days for traps-and cis-cypermethrin, respectively. Both isomers of cypermethrin underwent epimerization to (1 S)-isomers, cis/trans isomerization, ester bond cleavage, hydroxylation of the phenoxy group in the alcohol moiety or the geminal methyl group in the acid moiety, hydration of the CN group to the CONH2 group with subsequent hydrolysis to the COOH group, and conjugation of the resultant carboxylic acids and alcohols with sugars. The major metabolites from the alcohol moiety were glycoside conjugates of 3-(4-hydroxyphenoxy)benzoic acid and 3-phenoxybenzoic acid, and glycoside conjugates of 3-(2, 2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid from the acid moiety. Cypermethrin and its metabolites hardly translocated from the treated leaves to other parts of the plants.

Tomato Metabolism and Porphyrin-Catalyzed Oxidation of Pyriproxyfen

“…Therefore, metabolic pathways of 1 seemed to be partly common among plants, mammals, fishes, and insects. As for the hydroxylation at the phenyl ring, a similar reaction has been reported for fenoxycarb (20) and some pyrethroids (19,(21)(22)(23)(24)(25)(26). These common profiles are supposed to be related to oxidases in plants.…”

Persistence, Penetration, and Surface Availability of Cypermethrin and Its Major Degradation Products in Elm Bark

“…The dissipation of cypermethrin has been studied on cotton leaves (Ware et al, 1983), wheat leaves (Westcott and Reichle, 1987), celery and lettuce (Braun et al, 1987), and cabbages (Furuzawa et al, 1981). The halflife for total cypermethrin in crop plants was several days.…”

“…The halflife for total cypermethrin in crop plants was several days. Furuzawa et al (1981) reported different halflives for cis-and trans-cypermethrin isomers in cabbage. The initial degradation half-lives of trans-and ciscypermethrin on and in treated cabbage leaves were 4-5 and 7-8 days, respectively, indicating that the trans-isomers degraded approximately twice as quickly as the cis-isomers.…”

“…The initial degradation half-lives of trans-and ciscypermethrin on and in treated cabbage leaves were 4-5 and 7-8 days, respectively, indicating that the trans-isomers degraded approximately twice as quickly as the cis-isomers. Furuzawa et al (1981) studied the metabolic pathways of (1R)-cis-and (1R)-trans-isomer individuals on and in cabbages with 14 C preparations labeled separately in the benzyl ring and cyclopropyl ring. They reported that the metabolic pathways of both isomers of cypermethrin included epimerization to (1S)-isomers, cis/trans-isomerization, ester bond cleavage, hydroxylation of the phenoxy group in the alcohol moiety or the geminal methyl group in the acid moiety, hydration of the CN group to the CONH 2 group, which subsequently hydrolyzed to the COOH group, and conjugation of the resultant carboxylic acids and alcohols with sugars.…”

Isomerization of chiral pesticides in the environment

“…48,[117][118][119] Pyrethroids are generally susceptible to enzymatic hydrolysis and oxidation to form many metabolites in plant tissues, and the stereoisomers formed were mainly detected in a fraction of the plant surface rinse. Therefore, the observed isomerization in the cyclopropyl moiety is most likely to proceed photochemically under sunlight exposure, while no enantiomerization at 2-position of the acid moiety in fluvalinate (22) was observed.…”