Synthesis and photodynamic properties of 5,10,15,20-tetrakis[3-(N-ethyl-N-methylcarbazoyl)]chlorin and its analogous porphyrin in solution and in human red blood cells

The spectroscopic and the photodynamic properties of 5,10,15,20-tetrakis[3-(N-ethyl-N-methylcarbazoyl)]chlorin (TEMCC) and its analogous porphyrin (TEMCP) were investigated in N,N-dimethylformamide (DMF) and in human red blood (HRB) cells. A more intense absorption band at 650 nm was obtained for TEMCC in comparison with TEMCP. Both photosensitizers showed red fluorescence emission with quantum yields of 0.13 and 0.23 for TEMCP and TEMCC, respectively. The photodynamic activity of TEMCC was higher that TEMCP in DMF, with a quantum yield of singlet molecular oxygen of 0.49. Moreover, in presence of NADH these photosensitizers produced superoxide anion radical. In vitro experiments showed that TEMCC was a highly effective agent to hemolyze the HRB cells. A decrease in the HRB cells osmotic stability was observed after photodynamic treatment with TEMCC. Studies of photodynamic action mechanism showed that the photohemolysis of HRB cells was protected in the presence of azide ion. Also, a reduction on the cell photodamage was found using mannitol. In contrast, the photohemolytic effect considerably increased in D2O. Therefore, the photodynamic activity of TEMCC in HRB cells was mediated by a contribution of type I and type II photooxidative mechanisms.