Streptothricin F is a bactericidal antibiotic effective against highly drug-resistant gram-negative bacteria that interacts with the 30S subunit of the 70S ribosome
Fig 4
Cytotoxicity of streptothricins against mammalian cell lines.
J774 macrophages and LLC-PK-1 renal epithelial cells were treated with 2-fold doubling dilutions of nourseothricin, S-D, and S-F for up to 5 days in the presence of SYTOX-Green. SYTOX-Green is a cell membrane-impermeant nucleic acid binding dye that fluoresces on binding to nuclear DNA. It therefore provides a real-time readout of eukaryotic cell membrane permeabilization associated with cell death that can be continuously monitored through fluorescence measurements. Cytotoxicity was minimal to absent after a single day incubation but increased on subsequent days. Nourseothricin and S-D effects were essentially indistinguishable. S-F toxicity was only observed at molar concentration at least 10-fold greater than S-D beginning at 32 μM, significantly above MIC ranges observed in activity spectrum analysis. Each data point represents mean and standard deviation for assays performed in quadruplicate. Data are available in S4 Data. MIC, minimal inhibitory concentration; S-D, streptothricin D; S-F, streptothricin-F.