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-a5, a novel photosensitizer. The characteristic absorption bands (Soret and Q-bands, λmax = 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 (ΦΔ = 0.22) was higher than free pheophorbide-a (ΦΔ = 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 μg/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.
光敏剂在可见光照射下可产生高活性的单线态氧,可用于光动力疗法,治疗多种肿瘤。我们报告了一种新型光敏剂--三乙二醇树枝状连接的pheophorbide-a5的合成过程。由于树枝状分子的水溶性提高,5 的特征吸收带(Soret 带和 Q 带,λmax 分别为 405 纳米和 670 纳米)在水溶液中清晰显现。在水溶液中,5 的单线态氧量子产率值(ΦΔ = 0.22)高于作为参考的游离菲-a(ΦΔ = 0.17)。在 1.0-5.0 μg/mL 的浓度范围内,化合物 5 的体外光毒性也比pheophorbide-a(PhA)更强:用 5 处理的细胞存活率降低了约 20%,表明细胞死亡率约为 80%,而用 PhA 处理的细胞死亡率仅约为 10%。这些结果表明,5 在光导放疗应用中可能会更有效。与游离 PhA 相比,化合物 5 显示出高度增强的单线态氧生成能力和体外光细胞毒性。