Synthesis and characterization of indium(III) phthalocyanines with different Schiff Base groups for application in photodynamic therapy

Abstract

Indium(III) phthalocyanines bearing different types of Schiff base groups and their quaternized cationic phthalocyanine derivatives were synthesized and characterized by various spectroscopic techniques such as UV-Vis, FT-IR, 1H NMR, mass spectra and elemental analysis. The photophysical and photochemical properties of new indium(III) phthalocyanines were investigated in DMSO for non-ionic phthalocyanines and in both DMSO and aqueous solution for quaternized cationic phthalocyanines. Compared to the unsubsituted ZnPc in DMSO (Phi Delta = 0.67), all studied quaternized phthalocyanines gave good singlet oxygen quantum yield (0.64 for In1c, 0.80 for In2c, 0.89 for Q-In1c and 0.73 for Q-In2c) in DMSO. Also, the binding behaviour of cationic indium(III) phthalocyanines to DNA and BSA were investigated. BSA binding studies showed that quaternized indium(III) phthalocyanines bound to BSA via static quenching. Moreover, Q-In1c and Q-In2c (Kb/105 (M- 1) = 4.0 for both) strongly linked to CT-DNA. Water soluble quaternized indium(III) phthalocyanines also interacted with CT-DNA by intercalation. The use of indium(III) phthalocyanines in PDT led to a decrease in cell viability and the induction of apoptotic cell death, using a non-toxic concentration. Additionally, PDT mediated by indium(III) phthalocyanines resulted in a decrease in SOD activity and an increase in MDA levels in prostate cancer cells. These results emphasize the potential of the synthesized indium(III) phthalocyanines as promising photosensitizers for achieving effective PDT.