Figure 4.

Myrtenol-lum penetration into S. aureus cells. (a) The localization of either (−)-myrtenol or (+)-myrtenol carrying the fluorophore BODIPY (Myrtenol-lum) assessed by confocal laser scanning microscopy. The solely fluorophore (lum) and Calcofluor-White (CFW) membrane dyes served as references. (b) Penetration of myrtenol-lum into S. aureus cells. Myrtenol-lum was added to S. aureus cells, and the sole fluorophore (lum) was used as a control. After 4, 8, 16, 32, and 64 min of incubation, cells were harvested, washed with PBS, and residual fluorescence was measured. The half-time of penetration (t½) was 24 ± 1.3 min and 26 ± 1.5 min for (−)-myrtenol and (+)-myrtenol, respectively, while for the fluorophore solely (lum) was t½ > 5000 min.