Mechanistic insight into the photodynamic effect mediated by porphyrin-fullerene C₆₀ dyads in solution and in Staphylococcus aureus cells

Abstract

The photodynamic action mechanism sensitized by a non-charged porphyrin-fullerene C60 dyad and its tetracationic analogue was investigated in solution and in Staphylococcus aureus cells.

Mechanistic Insight into the Photodynamic Effect Mediated by Neutral Red and a New Azine Compound in Staphylococcus aureus Cells

“…Sodium azide has been frequently used as a physical quencher of 1 O 2 . Nevertheless, several reports show that contrary to what was expected, sodium azide did not prevent the bacterial killing of different PS, but rather potentiated them .…”

“…The simplest approach for determining whether 1 O 2 or free radicals are involved in the photodynamic process, is to study the inhibitory effect of scavengers, which can intercept the ROS at high rates and in a selective manner . In particular, mannitol and azide ion are used directly in biological media . Mannitol has the ability to deactivate superoxide anions and HO • , evidencing their participation in reactions mediated by free radicals.…”

“…Mannitol has the ability to deactivate superoxide anions and HO • , evidencing their participation in reactions mediated by free radicals. This implies that the substrate inhibits cell death caused by PS acting on type I reactions . On the other hand, azide ion presents the capacity to deactivate intracellular 1 O 2 by physical quenching and to act as a scavenger for free radicals derived from oxygen, being indicative of both processes, type I and type II .…”

“…[8] In particular, mannitol and azide ion are used directly in biological media. [9,10] Mannitol has the ability to deactivate superoxide anions and HO * , evidencing their participation in reactions mediated by free radicals. This implies that the substrate inhibits cell death caused by PS acting on type I reactions.…”

“…This implies that the substrate inhibits cell death caused by PS acting on type I reactions. [10,11] On the other hand, azide ion presents the capacity to deactivate intracellular 1 O 2 by physical quenching and to act as a scavenger for free radicals derived from oxygen, being indicative of both processes, type I and type II. [10][11][12] Both mechanisms may occur in parallel or exclusively, and the ratio between these processes depends on the PS used, on the concentrations of substrate, and oxygen.…”