Enhanced in vitro photocytotoxicity of water-soluble dendritic pheophorbide-a

Abstract

Photosensitizers can produce highly reactive singlet oxygen with exposure to visible light and are used in photodynamic therapy to treat a variety of tumors. We report on the synthesis of triethylene glycol dendron-conjugated pheophorbide-a 5, a novel photosensitizer. The characteristic absorption bands (Soret and Q-bands, l max = 405 and 670 nm, respectively) of 5 were appeared clearly in aqueous solution, due to the improved water-solubility of the dendron moiety. The value of singlet oxygen quantum yield of 5 (F D = 0.22) was higher than free pheophorbide-a (F D = 0.17) as reference in aqueous solution. Compound 5 also exhibited an enhanced in vitro phototoxicity than pheophorbide-a (PhA) in the concentration range of 1.0-5.0 mg/mL: cell viability in cells treated with 5 was reduced by ~20%, indicating a cell death rate of ~80%, while PhA treatment resulted in a cell death rate of only about 10%. These results indicate that 5 will likely be more efficient in PDT applications. Compared with free PhA, compound 5 showed highly enhanced singlet oxygen generation ability and in vitro photocytotoxicity.

Synthesis of a poly(ethylene glycol) galloyl sensitizer tip for an ’all‐in‐one' photodynamic device

“…Other research groups have reported on pheophorbide and chlorin derivatives for efficient photosensitized eradication of tumor cells by alleviating solubility and aggregation problems. We and others have observed that polyethylene glycol (PEG) groups bonded to chlorophyll sensitizers can increase their solubility in solution, cell uptake, and phototoxicity in cancer cells. But previous work with chlorin e 6 had required chemically bonding each PEG group individually, with the third PEG adding in low yield (triPEG‐chlorin silica 2 and triPEG‐chlorin Teflon/PVA nanocomposite 3 , Figure ).…”