Excretion balance, metabolic fate, and tissue residues of N-Phenyl-N'-1,2,5-Thiadiazol-3-Ylurea (Photothidiazuron) in rats
"Thidiazuron (DROPP®) or N-phenyl-N'-1,2,3-thiadiazol-5-ylurea is a promising new cotton defoliant currently being developed by NOR-AM Agricultural Products, Incorporated. In addition to its defoliating activity, thidiazuron demonstrates strong inhibition of regrowth with no adverse effect on the opening or quality of fiber of mature bolls not open at the time of application (Anonymous, 1975). These attributes indicate this could be a useful product. With the possibility of widespread use of thidiazuron in cotton growing regions, it is necessary to consider the result of its photodegradation. The major thidiazuron conversion product, which occurs on the plant surface, is photothidiazuron or N-phenyl-N'-1,2,5-thiadiazol-3-ylurea (Anonymous, 1976). This new compound is the result of a rearrangement in the thiadiazol moiety (Anonymous, 1976). Thidiazuron and photothidiazuron are classified chemically as substituted ureas. This includes a broad group of compounds varying greatly in their molecular substituents and commercial uses. However, most substituted ureas are herbicides, and therefore, the orientation of research has been directed to plant and soil situations. Research data pertaining to the effects of substituted ureas upon mammalian and other animal systems is very limited (Geissbuhler, et al., 1975). Since it is possible that leaves and other parts of a thidiazuron treated cotton plant may be incorporated into livestock feed or eaten by other animals, it is essential to examine certain of the properties of photothidiazuron in relation to mammalian systems. The purpose of this study was to determine the excretion balance, metabolic fate, and tissue residues of photothidiazuron in rats. Specifically, the objectives were: 1. To determine the excretion balance, metabolic fate, and tissue residues after the administration of a single oral dose of photothidiazuron-14 aniline- C to male rats, 2. To investigate the degradation of photothidiazuron by rat liver subcellular fractions and by a model hydroxylation system, and 3. To identify major photothidiazuron metabolites."--Introduction.