Susceptibility of Candida albicans to photodynamic action of 5,10,15,20-tetra(4-N-methylpyridyl)porphyrin in different media

E. D. QUIROGA, M. G. ALVAREZ, E. N. DURANTINI.

FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2010 p. 123 - 131

0928-8244

The photodynamic activity of 5,10,15,20-tetra(4-N-methylpyridyl)porphyrin (TMPyP) was evaluated in vitro on Candida albicans cells under different experimental conditions. This tetracationic porphyrin is rapidly bound to C. albicans cells, reaching a value of ~1.7 nmol/106 cells, when the cellular suspensions (106 CFU/mL) were incubated with 5 mM sensitizer. The amount of cell-bound sensitizer is not appreciably changed incubating the cultures for longer times (>15 min) but it diminishes with the number of washing steps. Photosensitized inactivation of C. albicans cellular suspensions increases with both sensitizer concentration and irradiation time, causing a ~5 log decrease of cell survival, when the cultures are treated with 5 mM TMPyP and irradiated for 30 min. However, the photocytotoxicity decreases after one washing step, according with lower binding of sensitizer to cells. Also, the growth of C. albicans cells was arrested when the cultures were exposed to 5 mM TMPyP and visible light. On agar surfaces, the phototoxic effect of this sensitizer remained high to inactivate C. albicans cells. No growth was observed in areas containing TMPyP and irradiated. Moreover, a complete inactivation of C. albicans cells was obtained in small C. albicans colonies. These studies indicate that TMPyP is an effective sensitizer for photodynamic inactivation of yeasts in both liquid suspensions or localized on a surface.