Comparison between porphin, chlorin and bacteriochlorin derivatives for photodynamic therapy: Synthesis, photophysical properties, and biological activity.

The development of novel photosensitizers is a challenging task for photodynamic therapy (PDT). Twelve novel photosensitizers (PSs), including porphins (P1-4), chlorins (C1-4) and bacteriochlorins (B1-4) were synthesized. The bacteriochlorins exhibited the longest absorption wavelength (λmax  = 736 nm), which is higher than that of porphins (λmax  = 630 nm) and chlorins (λmax  = 644 nm). In vitro photodynamic activities on Eca-109 human esophageal carcinoma cells were evaluated by standard assays and all PSs showed photodynamic activity. Among them, B2 displayed the highest phototoxicity and the lowest dark toxicity. In addition, B2 exhibited best photodynamic antitumor efficacy on BALB/c nude mice bearing Eca-109 cells tumor. Therefore, B2 is a powerful and promising antitumor photosensitizer for PDT.