High-Throughput Screen for Identifying Small Molecules That Target Fungal Zinc Homeostasis

Resistance to traditional antifungal drugs has increased significantly over the past three decades, making identification of novel antifungal agents and new targets an emerging priority. Based on the extraordinary zinc requirement of several fungal pathogens and their well-established sensitivity to zinc deprivation, we developed an efficient cell-based screen to identify new antifungal drugs that target the zinc homeostasis machinery. The screen is based on the zinc-regulated transcription factor Zap1 of Saccharomyces cerevisiae, which regulates transcription of genes like the high-affinity zinc transporter ZRT1. We generated a genetically modified strain of S. cerevisae that reports intracellular zinc deficiency by placing the coding sequence of green fluorescent protein (GFP) under the control of the Zap1-regulated ZRT1 promoter. After showing that the GFP fluorescence signal correlates with low intracellular zinc concentrations in this strain, a protocol was developed for screening small-molecule libraries for compounds that induce Zap1-dependent GFP expression. Comparison of control compounds and known modulators of metal metabolism from the library reveals a robust screen (Z′ = 0.74) and validates this approach to the discovery of new classes of antifungal compounds that interfere with the intracellular zinc homeostasis. Given that growth of many pathogenic organisms is significantly impaired by zinc limitation; these results identify new types of antifungal drugs that target critical nutrient acquisition pathways

Preliminary Safety Assessment of New Azinesulfonamide Analogs of Aripiprazole using Prokaryotic Models

Purpose: Determination of the mutagenic potential of new biologically active compounds is of great concern for preliminary toxicity testing and drug development. Methods: The mutagenic and antimutagenic effects of some quinoline- and isoquinoline-sulfonamide analogs of aripiprazole (1-8), which display potent antidepressant, anxiolytic, and antipsychotic properties, were evaluated using the Vibrio harveyi assay and OSIRIS Property Explorer software. Additionally, the Ames test was used as the reference. Results: In silico prediction showed that compounds 5 (N-(3-(4-(2,3-dichlorophenyl)piperazin-1-yl)propyl)quinoline-7-sulfonamide) and 6 (N-(4-(4-(2,3-Dichlorophenyl)piperazin-1-yl)butyl)quinoline-7-sulfonamide) trigger a mutagenic structural alert. However, this was not confirmed by in vitro assays, as none of the tested compounds displayed mutagenic activity against all tested strains of bacteria. Moreover, compounds 1-8 displayed a protective effect against the mutagenicity induced by a direct acting mutagen NQNO. The most beneficial antimutagenic properties showed compound 5 which exhibited strong antimutagenic properties in all tested V. harveyi strains. High antimutagenic potency of this compound was confirmed in the Ames TA100 assay system. Conclusion: Newly synthesized azinesulfonamide analogs of aripiprazole may be considered as genotoxically safe as they do not display mutagenic activity on the tester strains. Moreover, the tested compounds demonstrated significant antimutagenic properties that can be valuable for prevention of the NQNO genotoxicity. Additionally, it appears that the Vibrio harveyi assay can be applied for primary mutagenicity and antimutagenicity assessment of chemical substances, thus, representing a useful alternative tool for compounds safety evaluation