Metabolism of the synthetic pyrethroid fenpropathrin in plants

Abstract

The metabolic fate of fenpropathrin [(i?S)-a-cyano-3-phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate] in cabbages was studied by using 14C preparations labeled separately at the cyano group and the benzyl and cyclopropyl rings. By foliar treatment in a greenhouse, the insecticide disappeared with the the initial half-life of approximately 11-12 days. The insecticide underwent ester cleavage, hydroxylation at either or both of the gem-dimethyl groups with subsequent oxidation to the carboxylic acid, hydroxylation at the 2or 4-position of the phenoxy group, and hydrolysis of the CN group to the CONH2 and COOH groups. Most of the carboxylic acids and alcohols thus produced occurred as glycoside conjugates. 2,2,3,3-Tetramethylcyclopropanecarboxylic acid, the acidic half of the molecule, was converted mainly to glucose conjugate in abscised leaves of apple and vine, to malonylglucoside in cabbage, orange, and bean plants, and to gentiobioside in tomato. H14CN in abscised leaves of cabbage was rapidly incorporated into /3-cyanoalanine, asparagine, aspartic acid, and 7-glutamyl-/3-cyanoalanine, with ultimate formation of 14C02 and bound 14C residues. Little 14C was detected in the shoot portions of bean plants grown to maturity in soils treated with 14C-fenpropathrin at a rate of 1 ppm.

Metabolism of Tolclofos-methyl in Lettuce (Lactuca sativa)

“…Significantly less formation of VI than VII indicates that the subsequent conjugation of VI with malonic acid occurs more rapidly than the O-glucosylation. It has been reported that malonylglucose conjugates are more common in cabbage than other plants [16][17][18] with higher levels as compared with glucose conjugates, 19) which is good agreement with our observation. Koester et al 20) have reported that a malonyltransferase catalyzing the malonylation of glucose conjugates of isoflavone derivatives exhibits substrate specificity.…”

Characterization of cell-free extracts from fenpropathrin-degrading strain Bacillus cereus ZH-3 and its potential for bioremediation of pyrethroid-contaminated soils

“…In addition, the formation of phenol suggested two benzene rings in the alcohol moiety of fenpropathrin eventually separated and formed simple and stable compounds in this microbial degradation. However, research findings pointed out that oxidation at methyl groups of acid moiety is also involved in fenpropathrin metabolic reactions (Mikami et al, 1985). A series of oxidative products of fenpropathrin acid moiety were not detected in this study, which might suggest that the oxidation products were transient and rapidly transformed into other simple structures.…”

“…First, the cleavage of ester linkage of fenpropathrin occurred because of the detection of α-hydroxy-3-phenoxy-benzeneacetonitrile. It was reported that the hydroxylation at 4′-position of the alcohol moiety is a major reaction in fenpropathrin metabolism (Casida and Ruzo, 1980;Mikami et al, 1985;Liu et al, 2014). Based on the chemical structures, hence, it is suggested that α-hydroxy-3-phenoxy-benzeneacetonitrile can be an initial hydroxylation product of fenpropathrin, which was unstable and spontaneously transformed into 3-phenoxybenzaldehyde.…”

Curative Activity of Insecticides Against Plum Curculio (Coleoptera: Curculionidae) in Tart Cherries

“…Rain washoff is an unlikely contributor; there was Ͻ0.05 cm at CHES during the entire postspray interval, and NWHRS precipitation was limited to 2.4 cm 7 d after application. The lack of residue could be due to inefÞcient penetration through the cherry cuticle, or it could be a function of metabolic breakdown of this compound within the fruit tissue after penetration (Mikami et al 1985). Ester hydrolysis is the major metabolic pathway for esfenvalerate, and both plants and animals possess enzymes that mediate this process.…”