Figure 3. Y-axis: MIC ( µ g/mL) values of colistin alone or in combination with 12h and 13h as adjuvants, in Gram-negative bacteria and in MHB. X-axis: combination of colistin with compounds 12h and 13h at different concentrations. Growth was assessed both with unaided eye and using optical density measurements at 620 nm, and percent growth inhibition was calculated in comparison with cells incubated in a medium added with solvent alone (1% DMSO). The results are presented as the average of three independent experiments, each carried out in triplicate, ± standard deviation (* p < 0.05, ** p < 0.01, between colistin alone and the selected compounds at 8 µ g/mL, as determined by ANOVA). Table 3. FIC index of most potent combinations of compounds 12h and 13h with