Abstract
Metabolism of orbencarb (S-2-chlorobenzyl N, N-diethylthiocarbamate) in soybean, wheat, corn and crabgrass seedlings was studied under laboratory conditions. When [phenyl-U-14C] orbencarb was applied to the roots of each plant, radiocarbon derived from 14C-orbencarb was distributed throughout the whole plant for 96hr. In seedlings, the degree of radiocarbon movement to newly developed leaves in soybean was greater than that in wheat, corn or crabgrass.
As metabolites, sixteen compounds were tentatively identified by thin layer co-chromatography with the authentic compounds as free or methyl esters. Four plant species converted the 2-chlorobenzyl moiety of orbencarb to S-(2-chlorobenzyl)-L-cysteine, S-(2-chlorobenzyl)-N-malonyl-L-cysteine and its sulfoxide. The amounts of the cysteine containing metabolites based on the radioactivity in plants were 19.3, 12.5, 10.1 and 3.3% for soybean, wheat, corn and crabgrass, respectively, while the conversion to other major metabolites such as 2-chlorobenzyl alcohol and 2-chlorobenzoic acid showed a similar tendency in all plants. Since the same metabolites were detected in all plants, the metabolic pathway of orbencarb was suggested to be the same in each plant, and the formation of S-(2-chlorobenzyl)-L-cysteine derivatives was one of these important metabolic pathways.
