| Abstract: | [14C]ring-Bromoxynil octanoate was applied to the leaves of wheat seedlings, which were cultivated in a growth cabinet under controlled conditions for 14 days. Fractionation of the metabolites present in the treated leaves, which accounted for about 63% of the radioactivity applied, indicated a complex metabolic pathway resulting from initial hydrolysis to free bromoxynil, followed by three consecutive or concurrent steps (a) hydrolysis of the cyano group to the amide and carboxylic acid, followed by decarboxylation to 2,6-dibromophenol (0.5% of the 14C applied), (b) replacement of one or both bromine atoms by hydroxy groups to 3-bromo-4,5-dihydroxybenzonitrile (1.3 %) and 3,4,5-trihydroxybenzo-nitrile (0.6 %) or their hydrolysis products, (c) replacement of one or both bromine atoms by hydrogen, giving 3-bromo-4-hydroxybenzonitrile (1.9 %) and 4-hydroxy-benzonitrile (0.6%) or their hydrolysis products. Some of the phenolic acids or phenols formed are natural plant constituents. The metabolites identified represented in all about 11 % of the herbicide applied, but no individual metabolite accounted for more than a small proportion of it. |
