Screening of Pandemic Response Box Library Reveals the High Activity of Olorofim against Pathogenic Sporothrix Species

The increase in the prevalence and severity of fungal infections and the resistance to available antifungals highlights the imperative need for novel therapeutics and the search for new targets. High-content screening of libraries containing hundreds of compounds is a powerful strategy for searching for new drug candidates. In this study, we screened the Pandemic Response Box library (Medicines for Malaria Venture) of 400 diverse molecules against the Sporothrix pathogenic species. The initial screen identified twenty-four candidates that inhibited the growth of Sporothrix brasiliensis by more than 80%. Some of these compounds are known to display antifungal activity, including olorofim (MMV1782354), a new antifungal drug. Olorofim inhibited and killed the yeasts of S. brasiliensis, S. schenckii, and S. globosa at concentrations lower than itraconazole, and it also showed antibiofilm activity. According to the results obtained by fluorimetry, electron microscopy, and particle characterization analyses, we observed that olorofim induced profound alterations on the cell surface and cell cycle arrest in S. brasiliensis yeasts. We also verified that these morphophysiological alterations impaired their ability to adhere to keratinocytes in vitro. Our results indicate that olorofim is a promising new antifungal against sporotrichosis agents.

Automated summary

High-content screening of compounds from the Pandemic Response Box library identified olorofim as a promising new antifungal drug against Sporothrix pathogenic species. Olorofim showed inhibitory and lethal effects on several Sporothrix species at lower concentrations than itraconazole, and it also displayed antibiofilm activity. The drug induced significant alterations on the cell surface and cell cycle arrest in Sporothrix yeasts, impairing their ability to adhere to keratinocytes.