As the threat associated with fungal infections continues to rise and the availability of antifungal drugs remains a concern, it becomes obvious that the need to bolster the antifungal armamentarium is urgent. Building from our previous findings of tobramycin (TOB) derivatives with antifungal activity, we further investigate the effects of various linkers on the biological activity of these aminoglycosides. Herein, we analyze how thioether, sulfone, triazole, amide, and ether functionalities affect the antifungal activity of alkylated TOB derivatives against 22 Candida, Cryptococcus, and Aspergillus species. We also evaluate their impact on the hemolysis of murine erythrocytes and the cytotoxicity against mammalian cell lines. While the triazole linker appears to confer optimal activity overall, all of the linkers incorporated into the TOB derivatives resulted in compounds that are very effective against the Cryptococcus neoformans species, with MIC values ranging from 0.48 to 3.9 μg/mL.
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This work was supported by NIH grant AI090048 (to S.G.-T.).
The supplementary materials include 1H and 13C-NMR as well as mass spectra (Figures S1–S36) for the molecules synthesized. All compounds tested for activity are ≥95% pure according to NMR spectra. Table S1 with the % hemolysis ± SDEV displayed in Figure 1 is also provided.
Fosso, Marina Y.; Shrestha, Sanjib K.; Thamban Chandrika, Nishad; Dennis, Emily K.; Green, Keith D.; and Garneau-Tsodikova, Sylvie, "Differential Effects of Linkers on the Activity of Amphiphilic Tobramycin Antifungals" (2018). Pharmaceutical Sciences Faculty Publications. 104.