Porphyrins are used as photosensitizing agents in photodynamic therapy (PDT) for several pathologies. Here we demonstrate the DNA photocleavage and cytotoxicity properties of a free-base meso-tetra-ruthenated porphyrin (H₂RuTPyP) in purified DNA samples and in a melanoma cell line, respectively. Cytotoxicity of H₂RuTPyP was investigated by the tetrazolium dye (MTT) colorimetric assay and its genotoxic potential by direct plasmid DNA photocleavage after incubation with specific DNA repair enzymes. H₂RuTPyP porphyrin efficiently induced DNA damage at the lower concentration of 5.0 μM, whereas it induced complete DNA degradation at 15 μM. The addition of different scavengers for reactive oxygen species (ROS) during the visible light exposures did not decrease the DNA damage formation, suggesting a hydrolytic mechanism for the induction of DNA breaks. Also, H₂RuTPyP exhibited a much higher cytotoxicity in melanoma cells in comparison to a keratinocyte cell line. The detection of intracellular reactive oxygen species (ROS) produced by H₂RuTPyP through the DCF-DA assay also suggests that ROS have a minor role in the induction of cytotoxicity. Therefore, H₂RuTPyP seems to be a very effective photosensitizer, representing a promising alternative for the development of new skin cancer treatments using PDT process.

卟啉在光动力疗法（PDT）中被用作几种疾病的光敏剂。在这里，我们分别证明了纯化的DNA样品和黑色素瘤细胞系中的游离碱内消旋-四钌卟啉（H ₂ RuTPyP）的DNA光裂解和细胞毒性。H ₄ RuTPyP的细胞毒性通过四唑鎓染料（MTT）比色测定法进行了研究，并在与特定DNA修复酶孵育后通过直接质粒DNA的光裂解来研究了其遗传毒性潜力。H ₂ RuTPyP卟啉在5.0μM的较低浓度下有效诱导DNA损伤，而在15μM的条件下诱导DNA完全降解。在可见光暴露期间添加不同的活性氧清除剂并不能减少DNA损伤的形成，这提示了诱导DNA断裂的水解机制。而且，与角质形成细胞系相比，H ₂ RuTPyP在黑素瘤细胞中表现出更高的细胞毒性。H ₂ RuTPyP通过DCF-DA分析检测到的细胞内活性氧（ROS）也表明ROS在诱导细胞毒性中的作用很小。因此，H ₂ RuTPyP 似乎是一种非常有效的光敏剂，代表了使用PDT工艺开发新的皮肤癌治疗方法的有希望的替代方法。