RESUMO
A possible stereospecific and/or stereoselective mechanism of biodegradation for metalaxyl and metalaxyl-M was studied to elucidate their behavior in sunflower plants and to compare their biodegradation. Greenhouse experiments were carried out to confirm the same efficacy of the two fungicides against infections by Plasmopara helianthi in sunflower plants. The two fungicides appear to have the same behavior regarding both the protection against plant infections and the mode of translocation and the rate and pathway of biotransformation, but we have evidence that this biotransformation process is enantioselective. Furthermore, we propose procedures for a chromatographic separation of enantiomers and acid metabolites of the fungicides and for the determination of the R:S ratio by HPLC chiral analyses. This study emphasizes the importance of examining the fate of both stereoisomers of a chiral agrochemical in an environmental system for the correct use of enantiomerically pure agrochemical compounds.
Assuntos
Alanina/análogos & derivados , Alanina/metabolismo , Fungicidas Industriais/metabolismo , Helianthus/metabolismo , Helianthus/microbiologia , Alanina/análise , Alanina/farmacologia , Biodegradação Ambiental , Fungicidas Industriais/análise , Fungicidas Industriais/farmacologia , Doenças das Plantas/microbiologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Esporos Fúngicos/fisiologia , EstereoisomerismoRESUMO
MO theoretical calculations were used with the aim to investigate the electronic properties of a number of sulphonylureas 1-8 which are employed as antifeedants. Quantum chemical descriptors [electron density, molecular electrostatic potential (MEP), the topology of frontier orbitals and reactivity index] were determined for these compounds, aimed both to obtain a deeper insight in their mechanism of action and to correlate these properties with their activity as inhibitors of ALS synthase.
