ABSTRACT
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.
Subject(s)
Neoplasms/drug therapy , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacology , Cell Line, Tumor , Humans , Photochemotherapy , Photosensitizing Agents/chemical synthesis , Singlet Oxygen/metabolismABSTRACT
Using stereoselective aldol-like condensation as a key methodology, a series of chlorophyll a-based long wavelength cationic chlorins were synthesized using methyl pyropheophorbide a (MPPa) and purpurin-18-N-methoxylimide methyl ester as starting materials. Such long wavelength cationic chlorins possess covalently linked cationic moieties (pyridinium or quinolinium) on the peripheral of their tetrapyrrole macrocycles. It was found that all long wavelength cationic chlorins showed their longest absorption maxima in the range of 712-763nm, making them potential photosensitizers in photodynamic therapy. The results of preliminary experiments probing in vitro photodynamic effects showed that the purpurinimide derivatives exhibit relatively high phototoxicity in HeLa cells as compared to MPPa derivatives.
