No abstract

A comparative study of the photodynamic and antioxidant activities of methyl pheophorbide-a (MPa, 1) and its transition metal(II) complexes (2-5) is described. Four transition metal complexes (palladium(II): 2, zinc(II): 3, cobalt(II): 4 and copper(II): 5) of MPa were prepared by reaction between the corresponding transition metal and 1, respectively, and were characterized by 1 H-NMR and UV-vis spectroscopic and mass spectrometric analyses. In vitro results show a photodynamic therapy (PDT) efficacy with A549 cells might be attributed to a heavy atom effect of the transition metal complexes of MPa. Among them, 4 and 5 showed higher photodynamic activity than that of 1 at the concentration of 5 µM at 24 h incubation after photoirradiation. The images of morphological change for 2-5 show evidence for the PDT effect with A549 cells. And the all transition metal complexes of MPa showed higher antioxidant activity than that of MPa, in which 4 showed the highest antioxidant activity.

A series of novel purpurinimides with long wavelength absorption were designed and synthesized to develop novel and potential photosensitizers. These compounds were investigated through reduction, oxidation, rearrangement reaction and amidation reactions of methyl pheophorbide a. They demonstrated a considerable bathochromic shift of the major absorption band in the red region of the optical spectrum (695–704 nm). Newly synthesized purpurinimides were screened for their antitumor activities, and showed higher photodynamic efficiency against A549 cell lines as compared to purpurin-18 methyl ester. The results revealed the novel purpurinimides could be potential photosensitizers.