Photodynamic Action Mechanism Mediated by Zinc( II ) 2,9,16,23‐Tetrakis[4‐( N ‐methylpyridyloxy)]phthalocyanine in Candida albicans Cells

The photoreaction type I/type II pathways mediated by zinc( II ) 2,9,16,23‐tetrakis[4‐( N ‐methylpyridyloxy)]phthalocyanine (Zn PP c 4+ ) was studied in C andida albicans cells. This photosensitizer was strongly bound to C. albicans cells at short times. After 30 min irradiation, 5  μ M Zn PP c 4+ produced ~5 log decrease in cell viability. Different probes were used to detect reactive oxygen species ( ROS ) in cell suspensions (~10 6 CFU mL −1 ). Singlet molecular oxygen, O 2 ( 1 Δ g ), was observed by the reaction with 9,10‐dimethylanthracene ( DMA ) and tetrasodium 2,2‐(anthracene‐9,10‐diyl)bis(methylmalonate) ( ABMM ), whereas the nitro blue tetrazolium ( NBT ) method was used to sense superoxide anion radical ( O 2 · − ). Moreover, the effects produced by an anoxic atmosphere and cell suspensions in D 2 O, as well as the addition of sodium azide and mannitol as ROS trapping were evaluated in the PDI of C. albicans . These investigation indicates that O 2 ( 1 Δ g ) is generated in the cells, although a minor extension other radical species can also be involved in the PDI of C. albicans mediated by Zn PP c 4+ .