Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/1998
Publication Date: N/A
Citation: Interpretive Summary: The phytotoxicity of sulfentrazone and its metabolites detected in soybean was investigated at the physiological, biochemical and molecular level. The metabolites of sulfentrazone were generally less active than sulfentrazone on intact tissue assays. The lower activity of the metabolites was associated with lesser inhibition of the target enzyme and lower accumulation of photodynamic pigment, relative to sulfentrazone.
Technical Abstract: Biological activities of sulfentrazone and its metabolic derivatives were investigated in an effort to elucidate the basis for soybean tolerance to this herbicide. All of the metabolic derivatives were less toxic than sulfentrazone as measured by electrolyte leakage from soybean leaf discs. Their in vivo activity correlated with the amount of protoporphyrin IX (Proto) accumulating in herbicide-treated tissues (i.e. more Proto accumulated in tissues treated with sulfentrazone than with the metabolites). Protoporphyrinogen oxidase (Protox) inhibition was 1.2, 0.35, 10 and 37 uM for sulfentrazone and its 3-hydroxymethyl, 3-desmethyl, and 3-carboxylic acid metabolic derivatives, respectively, and their binding affinities were related to their relative inhibitory potency. Oxidative degradation of sulfentrazone did not have a great influence on the overall shape of the molecule but affected the steric and electronic environment surrounding the methyl group on the triazolinone ring.