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

Abstract

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 binds rapidly to C. albicans cells, reaching a value of ∼1.7 nmol 10(-6) cells when the cellular suspensions (10(6) CFU mL(-1) ) were incubated with 5 μM sensitizer. The amount of cell-bound sensitizer is not appreciably changed when cultures are incubating 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 μM TMPyP and irradiated for 30 min. However, the photocytotoxicity decreases after one washing step, with the decrease in cell-bound sensitizer. The growth of C. albicans cells was arrested when the cultures were exposed to 5 μM TMPyP and visible light. On agar surfaces, the phototoxic effect of this sensitizer, which caused an inactivation of C. albicans cells, remained high. No growth was observed in areas containing TMPyP and irradiated. Moreover, in small C. albicans colonies, C. albicans cells were completely inactivated. These studies indicate that TMPyP is an effective sensitizer for photodynamic inactivation of yeasts in both liquid suspensions or localized on a surface.

Mechanistic Aspects of Photoinactivation of Candida albicans by Exogenous Porphyrins†

“…Yeast cultures treated without addition of the tested porphyrins, but illuminated with the same intensities of blue light (light control) showed no significant decrease in viability (about 0.2 orders of magnitude). Similar results of phototreatment of C. albicans with the cationic and anionic porphyrins were reported by other groups (13–15).…”

“…It can be concluded that the penetration of the charged porphyrins into the yeast cells is dependent not only on the quantity of the proteins in the medium, but also on the quality. In another study, TMPyP was shown to efficiently photoinactivate C. albicans in liquid medium (Sabouraud broth) and on agar‐plate (Sabouraud agar) surface (15). As the Sabouraud medium is similar to NB, it is not surprising that the results are similar to those in the present study.…”

“…C. albicans was found to be susceptible to photosensitization by azines, toluidine blue O, malachite green or methylene blue and was successfully photoeradicated with these photosensitizers (9–12). Treatment of these yeasts with tri and tetra cationic porphyrins was also investigated by several groups (13–15). Recently, cationic porphycenes were studied for their potential antimicrobial photodynamic inactivation on C. albicans (16).…”

Photodynamic Antifungal Chemotherapy†

“…Recently a new Pp, the tetracationic porphyrin 5,10,15,20‐tetra(4‐N‐methylpyridyl) porphyrin (TMPγP) demonstrated a high in vitro effectiveness for photodynamic inactivation of C. albicans colonies in both liquid suspensions and localized on a surface (52).…”

Porphyrin-Polyelectrolyte Nanoassemblies: The Role of Charge and Building Block Architecture in Self-Assembly

“…Porphyrins and metalloporphyrins are of great importance due to their role in numerous chemical, biological, and medical processes . For example, porphyrins represent medically active compounds in the photodynamic therapy of cancer and human immunodeficiency virus (HIV) .…”