New metabolites of monuron in excised cotton leaves

Abstract

Two new metabolites of 3-(4-chlorophenyl)-1-dimethylurea (monuron) have been isolated from cotton leaves. They have been identified as β- d-glucosides of 3-(4-chlorophenyl)-1-hydroxymethyl-1-methylurea and 3-(4-chlorophenyl)-1-hydroxymethylurea. After 24 hr, both O-glucosides constitute 20–25% of the methanol soluble monuron metabolites present in treated leaf tissues. The isolation and identification of these polar monuron metabolites provides direct evidence for the formation of N-hydroxymethyl intermediates in the oxidative N-demethylation of substituted phenylurea herbicides by higher plants. The significance of reactive N-hydroxymethyl intermediates, particularly 3-(4-chlorophenyl)-1-hydroxymethylurea, in the formation of β- d-glucosides and other polar, unknown methanol soluble and insoluble monuron residues in higher plants is discussed.