2.3. Sorbitol protection assay

The effect of the 8-hydroxyquinoline derivatives on the integrity of the fungal cell wall was evaluated by sorbitol protection assay. Minimum inhibitory concentrations (MICs) of 8-hydroxyquinoline derivatives 1–3 were determined by the standard broth microdilution (CLSI M27-A3 for Candida spp.; CLSI M38-A2 for dermatophytes) (Clinical and Laboratory Standards Institute, 2008a, Clinical and Laboratory Standards Institute, 2008b) in the absence and presence of 0.8 M sorbitol (Sigma-Aldrich) added to the RPMI 1640 growth medium (Gibco) as an osmoprotectant. Microplates were incubated at 35 °C and 30 °C for Candida spp. and dermatophytes, respectively. Experiments were carried out in duplicate for all three strains of each species. Anidulafungin (Pfizer, New York, USA) was used as positive control. MICs were measured after 2 and 7 days for Candida spp.; and after 4 and 7 days for dermatophytes (Escalante et al., 2008).