TABLE 2.
Mol-fraction partition coefficients of nystatin, Kp, for sterol-free and cholesterol- and ergosterol-containing POPC LUV determined by a spectroscopic (fluorescence) and a separation method (centrifugation)
|
Kp (× 104)
|
|||
|---|---|---|---|
| Lipid system* | xSterol | Fluorescence | Centrifugation |
| POPC | 0 | 1.4 ± 0.2 | 1.4 ± 0.3 |
| Cholesterol/POPC | 0.05 | 2.2 ± 0.2 | 1.5 ± 0.2 |
| 0.075 | 1.6 ± 0.3 | – | |
| 0.10 | 1.7 ± 0.2 | 1.7 ± 0.5 | |
| 0.15 | 1.7 ± 0.4 | – | |
| 0.20 | 1.9 ± 0.7 | 1.4 ± 0.4 | |
| 0.30 | 1.3 ± 0.5 | 1.3 ± 0.6 | |
| Ergosterol/POPC | 0.05 | – | 1.2 ± 0.2 |
| 0.075 | – | – | |
| 0.10 | – | 1.5 ± 0.4 | |
| 0.15 | – | – | |
| 0.20 | – | 1.7 ± 0.4 | |
| 0.30 | – | 1.4 ± 0.4 | |
*
It was considered that only the external leaflet of the lipid vesicles could establish an interaction with the antibiotic. The antibiotic concentration used in each assay was 7.5 μM, respectively.