LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
CESAM, Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal.
J Photochem Photobiol B. 2022 Aug;233:112502. doi: 10.1016/j.jphotobiol.2022.112502. Epub 2022 Jun 21.
The photodynamic inactivation (PDI) of microorganisms has gained interest as an efficient option for conventional antibiotic treatments. Recently, Si(IV) phthalocyanines (SiPcs) have been highlighted as promising photosensitizers (PSs) to the PDI of microorganisms due to their remarkable absorption and emission features. To increase the potential of cationic SiPcs as PS drugs, one novel (1a) and two previously described (2a and 3a) axially substituted PSs with di-, tetra-, and hexa-ammonium units, respectively, were synthesized and characterized. Their PDI effect was evaluated for the first time against Escherichia coli and Staphylococcus aureus, a Gram-negative and a Gram-positive bacterium, respectively. The photodynamic treatments were conducted with PS concentrations of 3.0 and 6.0 μM under 60 min of white light irradiation (150 mW.cm). The biological results show high photodynamic efficiency for di- and tetra-cationic PSs 1a and 2a (6.0 μM), reducing the E. coli viability in 5.2 and 3.9 log, respectively (after 15 min of dark incubation before irradiation). For PS 3a, a similar bacterial reduction (3.6 log) was achieved but only with an extended dark incubation period (30 min). Under the same experimental conditions, the photodynamic effect of cationic PSs 1a-3a on S. aureus was even more promising, with abundance reductions of ca. 8.0 log after 45-60 min of PDI treatment. These results reveal the high PDI efficiency of PSs bearing ammonium groups and suggest their promising application as a broad-spectrum antimicrobial to control infections caused by Gram-negative and Gram-positive bacteria.
光动力失活（PDI）作为传统抗生素治疗的有效选择，已受到关注。最近，由于 Si(IV)酞菁（SiPcs）具有显著的吸收和发射特性，因此作为微生物 PDI 的光敏剂（PS）备受关注。为了提高阳离子 SiPcs 作为 PS 药物的潜力，合成并表征了一种新型（1a）和两种先前描述的（2a 和 3a）轴向取代的 PS，它们分别带有二、四和六铵基单元。首次评估了它们对大肠杆菌和金黄色葡萄球菌的 PDI 效应，分别为革兰氏阴性菌和革兰氏阳性菌。光动力处理在 60 分钟的白光照射（150 mW.cm）下，用 3.0 和 6.0 μM 的 PS 浓度进行。生物结果表明，二价和四价阳离子 PS 1a 和 2a（6.0 μM）具有很高的光动力效率，分别使大肠杆菌的活力降低了 5.2 和 3.9 个对数（照射前黑暗孵育 15 分钟后）。对于 PS 3a，虽然仅用延长的黑暗孵育期（30 分钟），但也实现了类似的细菌减少（3.6 个对数）。在相同的实验条件下，阳离子 PSs 1a-3a 对金黄色葡萄球菌的光动力效应更为显著，PDI 处理 45-60 分钟后，减少了约 8.0 个对数。这些结果表明，具有铵基的 PS 具有很高的 PDI 效率，并暗示它们作为广谱抗菌剂具有控制革兰氏阴性菌和革兰氏阳性菌感染的应用前景。
