Tetflupyrolimet shows selectivity for plant dihydroorotate dehydrogenase over Aspergillus orthologs

Abstract Shared enzymatic targets between azoles used in agriculture as fungicides and clinical antifungals are hypothesized to have led to the drift of resistant fungal isolates from field to clinic, reducing efficacy of azoles in infectious disease treatment. Recent discovery of a novel herbicide, tetflupyrolimet, and a potential clinical antifungal, olorofim, both targeting dihydroorotate dehydrogenase (DHODH), raises concern that widespread use of tetflupyrolimet may similarly cause clinical resistance to olorofim in Aspergillus isolates migrating from agricultural settings. Using minimum inhibitory concentration analysis on Aspergillus subspecies, enzymatic assays of recombinant DHODH, and a series of DHODH knockout yeast strains complemented with various DHODH orthologs, we demonstrate that tetflupyrolimet is highly selective for plant DHODH over Aspergillus DHODH. Based on the inability of tetflupyrolimet to inhibit Aspergillus DHODH or hinder growth of various Aspergillus species, the data demonstrate that risk of olorofim resistance developing in Aspergillus due to agrochemical use of the herbicide tetflupyrolimet is minimal.