Synthesis and Evaluation of the Antifungal and Toxicological Activity of Nitrofuran Derivatives

Exposure Assessment of Nitrofuran Metabolites in Fish and Honey Produced in Armenia: A Pilot Investigation

In Armenia, the presence of nitrofuran residues in food products is unacceptable for both domestic sales and export. However, food may contain nitrofuran metabolites (NMs) due to the illegal use of these drugs in the agrofarming practice. This study aimed to identify NMs as the marker residues for nitrofurans in fish and honey produced in Armenia and assess the potential health risks associated with consuming these foods. The commodities studied were natural honey and three species of farmed fish produced by various regions nationwide. Concentrations of the marker metabolites (3-amino-2-oxazolidinone (AOZ), 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ), 1-aminohydantoin (AHD), and semicarbazide (SEM)) were determined through an enzyme-linked immunosorbent assay (ELISA) and verified using liquid chromatography-mass spectrometry (LC-MS/MS). Consumer groups were identified based on their average daily intake of foods. Health risk was assessed by calculating the margin of exposure (MOE). Reference values for health risk assessment were obtained from the European Food Safety Authority (EFSA). Results showed that 33.3% of fish samples and 44.4% of honey samples contained NMs, the mean concentrations ranging from 0.05 μg/kg to 0.52 μg/kg. All MOE values obtained were over 10,000, indicating that the detected concentrations of NMs in fish and honey produced in Armenia pose no health risk to consumers. However, these results highlight the illicit use of highly toxic substances and the need for improved control of farming practices.

Evaluation of the Anti-Histoplasma capsulatum Activity of Indole and Nitrofuran Derivatives and Their Pharmacological Safety in Three-Dimensional Cell Cultures

Histoplasma capsulatum is a fungus that causes histoplasmosis. The increased evolution of microbial resistance and the adverse effects of current antifungals help new drugs to emerge. In this work, fifty-four nitrofurans and indoles were tested against the H. capsulatum EH-315 strain. Compounds with a minimum inhibitory concentration (MIC₉₀) equal to or lower than 7.81 µg/mL were selected to evaluate their MIC₉₀ on ATCC G217-B strain and their minimum fungicide concentration (MFC) on both strains. The quantification of membrane ergosterol, cell wall integrity, the production of reactive oxygen species, and the induction of death by necrosis–apoptosis was performed to investigate the mechanism of action of compounds 7, 11, and 32. These compounds could reduce the extracted sterol and induce necrotic cell death, similarly to itraconazole. Moreover, 7 and 11 damaged the cell wall, causing flaws in the contour (11), or changing the size and shape of the fungal cell wall (7). Furthermore, 7 and 32 induced reactive oxygen species (ROS) formation higher than 11 and control. Finally, the cytotoxicity was measured in two models of cell culture, i.e., monolayers (cells are flat) and a three-dimensional (3D) model, where they present a spheroidal conformation. Cytotoxicity assays in the 3D model showed a lower toxicity in the compounds than those performed on cell monolayers. Overall, these results suggest that derivatives of nitrofurans and indoles are promising compounds for the treatment of histoplasmosis.