Resumen:
he photophysical, photoinduced pro-oxidant and antibacterial properties in vitro of the natural occurring Parietin (PTN; 1,8-dihydroxy-3-methoxy-6-methyl-9,10-anthraquinone) were evaluated. PTN was extracted from the lichen identified as Teleoschistes flavicans (Sw.) Norm. (Telochistaceae). Results indicate that in chloroform solution, PTN presents spectroscopic features corresponding to an excited-state intramolecular proton-transfer (ESIPT) state with partial ketoenoltautomerization. In argon-saturated solutions, the singlet excited state is poorly fluorescent (F = 0.03), decaying by efficient intersystem crossing to excited triplet state 3PTN*, as detected by laser-flash photolysis experiments. In presence of triplet molecular oxygen, the 3PTN* was fully quenched producing singlet molecular oxygen (1O2) with quantum yield of 0.69. In addition, in buffer solutions PTN has also the ability to generate superoxide radical anion (O2 −) in a human leukocytes model a