Photodynamic inactivation of Candida albicans sensitized by a chlorin under different morphological types

Photokilling of Candida albicans sensitized by 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]chlorin (TAPC) was studied in under different culture conditions. Planktonic yeast suspensions in PBS treated with 5 mM TAPC were eliminated after an irradiation of 5 min with white light. The addition of reactive oxygen species scavengers showed that singlet molecular oxygen was involved in the photoinactivation. Also, a contribution of type I mechanism was detected in the yeast inactivation. Under growth conditions, C. albicans was detained in presence of TAPC and white light irradiation. Moreover, photocytotoxic activity was evaluated in C. albicans pseudohyphae. A reduction of 5 log and 1.5 log were found in pseudohyphae survival suspended in PBS and human serum, respectively. This difference was assigned to a decrease in the binding of the photosensitizer to the pseudohyphae in the serum. Therefore, the photoinactivation of C. albicans cells in PBS was investigated in the presence of albumin. The interaction of TAPC with this protein produced a reduction in the photoinactivation. These studies allow determined the appropriated conditions to eradicate C. albicans under different culture conditions.