There has been growing effort in the scientific community to develop new antibiotics to address the major threat of bacterial resistance. One promising approach is the use of metal complexes that provide broader opportunities. Among these systems, polypyridine-ruthenium(II) complexes have received particular attention as drug candidates. Here, we prepared two new ruthenium(II) complexes with the formulation [Ru(DFO)(phtpy-R)Cl](PF₆), where phtpy = 4′-phenyl-2,2′:6′,2′′-terpyridine; R = –H(MPD1), –CH₃(MPD2); and DFO = 4,5-diazafluoren-9-one, and investigated their chemical, biochemical and antibacterial activities. These compounds exhibit photoreactivity and produce reactive oxygen species (ROSs). Photogeneration of singlet oxygen (¹O₂) was measured in acetonitrile with significant quantum yields using blue light, Φ = 0.40 and 0.39 for MDP1 and MPD2, respectively. Further studies have shown that MPD1 and MPD2 can generate superoxide radicals. Antibacterial assays demonstrated a significant enhancement in MIC (minimum inhibitory concentration) upon blue light irradiation (>32-fold), with MICs of 15.6 μg mL⁻¹ (S. aureus, ATCC 700698) and 3.9 μg mL⁻¹ (S. epidermidis, ATCC 35984) for both metal complexes. Interestingly, an MIC of 15.6 μg mL⁻¹ for MPD1 and MPD2 was observed against S. epidermidis ATCC 12228 under red light irradiation. The latter results are encouraging, considering that red light penetrates deeper into the skin. In addition, no significant cytotoxicity was observed in some mammalian cells, even upon light irradiation, supporting their potential safety. Altogether, these data show evidence of the potential use of these compounds as antimicrobial photodynamic therapeutic agents, enriching our arsenal to combat this worldwide bacterial threat.

中文翻译：

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含有 4,5-二氮杂氟烯-9-酮配体的特吡啶基钌配合物，具有光驱动增强的生物活性


科学界越来越努力开发新的抗生素，以应对细菌耐药性的主要威胁。一种有前途的方法是使用金属络合物，这提供了更广泛的机会。在这些系统中，聚吡啶-钌 （II） 配合物作为候选药物受到了特别关注。在这里，我们制备了两种新的钌 （II） 配合物，其分子式为 [Ru（DFO）（phtpy-R）Cl]（PF ₆ ），其中 phtpy = 4'-苯基-2,2'：6'，2''-三吡啶;R = –H（MPD1），–CH ₃ （MPD2）;和 DFO = 4,5-二氮杂氟烯-9-酮，并研究了它们的化学、生化和抗菌活性。这些化合物表现出光反应性并产生活性氧 （ROS）。使用蓝光在乙腈中测量单线态氧 （ ¹ O ₂ ） 的光生成，具有显着的量子产率，MDP1 和 MPD2 分别为 Φ = 0.40 和 0.39。进一步的研究表明，MPD1 和 MPD2 可以产生超氧自由基。抗菌测定表明，蓝光照射 （>32 倍） 后 MIC （最小抑制浓度） 显着增强，两种金属络合物的 MIC 分别为 15.6 μg mL ⁻¹ （金黄色葡萄球菌， ATCC 700698） 和 3.9 μg mL ⁻¹ （表皮葡萄球菌， ATCC 35984）。有趣的是，在红光照射下观察到 MPD1 和 MPD2 对表皮葡萄球菌 ATCC 12228 的 MIC 为 15.6 μg mL ⁻¹ 。考虑到红光可以更深入地渗透到皮肤中，后者的结果令人鼓舞。此外，即使在光照射下，在一些哺乳动物细胞中也没有观察到明显的细胞毒性，这支持了它们的潜在安全性。 总而言之，这些数据显示了这些化合物可能用作抗菌光动力治疗剂的证据，丰富了我们的武器库来对抗这种全球细菌威胁。