Photodynamic activity of amphyphylic porphyrins bearing basic amine groups

ANA C. SCANONE; MARÍA GABRIELA ALVAREZ ; EDGARDO N. DURANTINI.

Carlos Paz

Conferencia; 13th Latin American Conference on Physical Organic Chemistry CLAFQO13; 2015

Porphyrins have attracted considerable interest because of their notable ability as phototherapeutic agents. In particular, positively charged porphyrins have been proposed for the eradication of microbial infections by photodynamic inactivation (PDI). The positive charges on the tetrapyrrolic macrocycle appear to promote a tight electrostatic interaction with the cell envelops of microorganisms, increasing the efficiency of the photoinactivation processes.In this work, novel asymmetrically meso-substituted porphyrins bearing amino groups were synthesized as precursors of cationic photodynamic agents. The amphiphilic character of these porphyrins was increased by the presence of perfluorophenyl group. The basis amine groups in the periphery of the macrocycle can acquire positive charges at physiological pH values. Also, in these porphyrins the cationic centers are isolated from the porphyrin ring by a propoxy bridge, which provides a higher mobility of the charge.These photosensitizers showed the Soret band at ~422 nm and the four Q-bands between 515-650 nm. The fluorescence spectra presented two bands around 650 and 725 nm with emission quantum yields of ~0.1. These bands have been assigned to Qx(0-0) and Qx(0-1) transitions. This is a typical behavior for porphyrins with D2h symmetry and indicates that the porphyrin vibronic structure remains practically unchanged upon excitation. Moreover, these compounds produce singlet molecular oxygen, O2(1g), with quantum yields of ~0.4 in N,N-dimethylformamide. Therefore, these porphyrins offer a promising molecular architecture with potential applications in PDI of microbial cells. Further studies of photosensitization in vitro are presently in progress in our laboratory.