Amino acid synthesis herbicide effects

Chorismate is an intermediate in the biosynthesis of the aromatic amino acids tryptophan, phenylalanine, and tyrosine. Mammals do not synthesize these amino acids bom chorismate. Instead, they obtain the essential aromatic amino acids tryptophan and phenylalanine from the diet, and they can synthesize tyrosine from phenylalanine. Glyphosate is an effective herbicide because it prevents synthesis of aromatic amino acids in plants. But the compound has no effect on mammals because they have no active pathway for de novo aromatic amino acid synthesis. 

Phosphonomycin,—Yet another synthesis of phosphonomycin (22) has appeared (Scheme 6). The phosphonoaldehyde (23) was treated with pentan-3-one and cyclohexylamine to give (24), which was then converted into its oxime. Tosylation of this oxime followed by treatment with bicarbonate caused the molecule to fragment, liberating the dimethyl ester of (22). Disodium phosphonoacetic acid when administered orally or topically to mice infected with Herpes simplex virus will reduce significantly the mortality of mice caused by this virus. JV-Phosphonomethyl-glycine is a promising herbicide. Recent work has shown that it exerts its effect by inhibiting the biosynthesis of aromatic amino-acids. ... 

Some pesticides, such as the herbicides inhibiting synthesis of amino acids in plants, are extremely selective between plants and animals and very potent. The chitin synthesis inhibitors used as insecticides are also extremely selective, because only insects and crustaceans (and fungi) make chitin. The fungicides first described are also efficient and have a high degree of selectivity, but are likely to produce effects in animals and plants because they inhibit enzymes of great importance to many types of organisms. 

Nonetheless unanswered questions remain. What are the relative contributions of branched chain amino acid deficiency and AKB overabundance to the cytotoxic effects of the sulfonylurea and Imldazollnone herbicides Will the delineation of the cytotoxicity of AKB towards typhimurium, the only system in which it has been approached, provide relevant information towards the roles of this molecule in the Inhibition of plant growth Can herbicide-resistant alleles of ALS structural genes be used as dominant selectable markers In the transformation of a wide variety of sensitive cell lines What are the structural details of the interaction of ALS with the sulfonylurea and imldazollnone herbicides Are eukaryotic ALS Isozymes composed of nonldentlcal subunits How does SM cause cessation of DNA synthesis in plants In the next few years answers to some of these questions may emerge. 

Condensation with the appropriate components is widely represented in literature approach to fluoroaUcyl derivatives of oxazole. Fluoroalkyloxazoles are of interest due to their application as surface modifiers of hydrophilic polymers, polymeric films for second-order non-linear optics, effective herbicides, body-membrane penetration enhancers, and intermediates for the synthesis of unnatural a-amino acids [12]. Thus, the syntheses of the trifiuoromethylated 2-aminooxazoles 8 and 9 were performed by reacting commercially available trifiuorobromoacetone with five equivalents of urea or cyanamide in refluxing fe/t-butanol to afford the corresponding 4- and 5-trifluoro-methyl-2-aminooxazoles in 70 % and 14 % yields, respectively [13,14]. 

In this book, the major target sites of herbicide action are discussed in Chapters 1-5, with particular reference to photosynthesis amino acid, lipid, and carotenoid synthesis and other primary target sites. The effects of synergists or antagonists as modifiers of herbicide action are described in Chapter 6. 

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