Fdx (2.8 µmol, 3.0 mg, 1.0 equiv.) or S-Fdx (2.8 µmol, 3.0 mg, 1.0 equiv.) was dissolved in MeCN (5 mL), followed by addition of solvent II (5 mL). The solution was stirred at 37 °C for 2 h, before being cooled to 0 °C and at 0 °C neutralized with NaOH (1 M). Then, the solvent was evaporated in vacuo at 40 °C and the residual solid suspended in acetone, filtered (4 mm syringe filter, PTFE (hydrophilic), pore size: 0.22 μm, BGB Analytik AG), and the solvent removed by N2 blowdown evaporation to provide the product of the degradation experiment as a colorless solid (Fdx: 2.76 mg; S-Fdx: 2.67 mg).The solids were used for characterization of the antibacterial activity via broth microdilution assays by Microbiologics (for assay procedure see Supplementary information). A small sample of the neutralized mixture was subjected to UHPLC-MS analysis (UHPLC-MS B). For Fdx, the experiment was performed twice and the solid obtained after nitrogen blowdown analyzed via 1 H NMR analysis.