Sulfonylurea metabolic detoxification

The basis of selectivity of foramsulfuron in the presence of the safener isoxadifen-ethyl is a more rapid rate of metabolic detoxification in maize compared with target weeds, in which little or no degradation of the parent sulfonylurea occurs [51]. Three main routes of metabolism have been established in maize - a hydrolytic cleavage of the sulfonylurea bridge, a deformylation of the amino group and oxidative metabolism of the dimethoxypyrimidine ring. 

A6 Bentazon and sulfonylurea metabolism Herbicide detoxification [196]... 

Other detoxification mechanisms are also known. This diversity of metabolism by different plants and for different sulfonylurea molecules is responsible for the high selectivity found in different crops. Understanding this enzymatic and chemical diversity can facilitate the design of sulfonylureas with optimal selectivity for a particular crop. 

GSTs in plants were first studied because of their ability to detoxify herbicides (30, 16). GST-based metabolism imparts herbicide tolerance in several plant species especially to the sulfonylureas, aryloxyphenoxypropionates, triazinone sulfoxides, and thiocarbamates herbicide families that are susceptible to GSH conjugation (16,31-35). There is a positive correlation of both GSH levels and the activity of specific GST enzymes wifti the rate of herbicide conjugation and detoxification (36-39). 

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