Variety of 2,4-D metabolic pathways in plants; its significance in developing analytical methods for herbicides residues

Abstract

2,4-D in plants very rapidly undergoes various transformations and its predominant metabolic pathways and rates vary with different plant species. In bean and soybean plants major 2,4-D metabolites are 4-O-beta-D-glucosides of 4-hydroxy-2,5-dichloro- and 4-hydroxy-2,3-dichloro-phenoxy-acetic acids; in addition, considerable amounts of N-(2,4-dichlorophenoxyacetyl)-L-aspartic and N-(2,4-dichlorophenoxyacetyl)-L-glutamic acids are accumulating in them. Among 2,4-D metabolites in cereals there prevailed 1-O-(2,4-dichlorophenoxyacetyl)-beta-D-glucose while the glycoside of 2,4-dichlorophenol prevailed in strawberry plants.

2,4-D resistance in wild radish: reduced herbicide translocation via inhibition of cellular transport

“…Attempts to identify the wild radish 2,4-D metabolites using mass spectrometry have so far proved unsuccessful, so the chemical behaviour of the wild radish metabolites was compared with that of the well-characterized metabolites from wheat and bean (identified as predominantly carboxylic glucose esters and phenolic glycosides: Chkanikov et al , 1976 ; Hamburg et al , 2001 ). Representative HPLC and TLC separations of 2,4-D metabolites from plants harvested 96h after [ 14 C]2,4-D application are shown in Fig.…”

“…or acidified water (pH ~2, for partitioning). The latter samples were partitioned three times against diethyl ether and then 1-butanol according to Chkanikov et al (1976) . Following butanol partitioning of the first aqueous phase, none of the 14 C-labelled compounds was detectable in the remaining water phase, as checked by LSC.…”

Enhanced 2,4-D Metabolism in Two Resistant Papaver rhoeas Populations from Spain

“…To study the 2,4-D metabolism in P. rhoeas , some known methodologies were used (Chkanikov et al, 1977 ; Hamburg et al, 2001 ) to confirm the existence or not of its metabolites in the populations. These methodologies were adapted and modified to be able to work without radiolabelled herbicide, because it was not possible to obtain 14 C-2,4-D metabolites.…”

“…The extraction followed the methodology described by Chkanikov et al ( 1977 ) with some modifications for the full extraction. Frozen samples were washed with 5 mL of 0.05 N of ammonium hydroxide.…”

Hydrophobic metabolites of 2,4-dichlorophenoxyacetic acid (2,4-D) in cultured coconut tissue

“…The resistance of metabolite II to proteolytic digestion rules out the possibility that the conjugate was with a bipeptide (or longer peptide chain) and suggested that the 2,4-D was not conjugated via a peptide (amide) bond. The failure to liberate an acidic metabolite after attempted chemical hydrolysis appears to confirm this view but it is possible that the conditions chosen for hydrolysis, 1 M KOH which is appropriate for lipid hydrolysis, were not sufficiently rigorous for amide bonds, with 7 M alkali being used on occasion (Chkanikov et al, 1976;Nazarova Fig. 2.…”