Synthesis of azoxystrobin transformation products and selection of monoclonal antibodies for immunoassay development

The use of agrochemicals for crop protection may result in the presence of toxic residues in soils and aquatic environments, besides in foodstuffs. Most often just the parent compound is included in the definition of pesticide residue, even though chemicals resulting from biotransformation and degradation routes might also be of toxicological relevance. Azoxystrobin is a broad-spectrum systemic fungicide widely used worldwide to combat pathogenic fungi affecting plants. We herein report the synthesis and detailed chemical characterization of several of the most relevant metabolites and degradates of azoxystrobin. These compounds were further employed as ligands for screening a collection of monoclonal antibodies to azoxystrobin, which had been previously generated from haptens functionalized at different positions of the target chemical. As a result, an antibody was identified capable of binding, with subnanomolar affinity, not only azoxystrobin but also its main transformation products, such as the so-called acid and enol derivatives, as well as the azoxystrobin (Z)-isomer. The selected binder was demonstrated as a useful immunoreagent for the development of immunochemical assays as novel analytical tools for the qualitative determination of azoxystrobin and its metabolites and degradates.

► Five of the most relevant transformation products of azoxystrobin were synthesized and thoroughly characterized.
► The synthesized compounds were employed as ligands for screening a collection of anti-azoxystrobin monoclonal antibodies.
► An antibody (mAb AZa6#210) was identified displaying subnanomolar affinity to three azoxystrobin breakdown products.
► The selected binder is the first ever reported antibody against azoxystrobin transformation products.
► The described generic monoclonal antibody is suitable for implementation in different immunoanalytical platforms.