English to French Medical Chemistry; Chem Sci/Eng herbicides

Tembotrione is classified as Group 27 Herbicide (refer to DIR99-06 for details at http://www.pmra-arla.gc.ca/english/pdf/dir/dir9906-e.pdf). The primary mode of action of tembotrione is as an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD) in the biosynthesis of plastoquinones, tocopherols and carotenoids. Blockage of the pathway at this enzymatic site leads to disturbed chloroplast synthesis and function as well as to photobleaching by oxidative degradation of chlorophyll and destruction of the photosynthetic membranes. Sensitive weed species exhibit symptoms within 2 - 5 days in the form of strong bleaching effects, particularly on the growing zones of the shoot. After treatment, growth is inhibited, chlorotic tissues become necrotic under the influence of light, and sensitive plants typically die within 14 days