Bilgin, MerveElgün, TuğbaAktaş, ÇiğdemKaragülle, Onur OlgaçÇınar, KamilGök Yurttaş, Asiye2026-11-122026-11-122026Bilgin, M., Elgün, T., Aktaş, Ç., Karagülle, O. O., Çınar, K., & Gök Yurttaş, A. (2026). Photoinactivation of MRSA AТCC 33591 by antimicrobial photodynamic therapy using coumarin-functionalized zinc(II) phthalocyanine. Acta Chimica Slovenica, 73(3), pp. 515-521. https://doi.org/10.17344/acsi.2025.96381318-02071580-3155https://doi.org/10.17344/acsi.2025.9638https://hdl.handle.net/20.500.13055/1713This study evaluates the photodynamic inactivation potential of a coumarin-functionalized zinc(II) phthalocyanine derivative against methicillin-resistant Staphylococcus aureus (MRSA) AТСC 33591. The antimicrobial and cytotoxic effects of the derivative were assessed under dark and laser-irradiated (658 nm) conditions. Minimum inhibitory concentration (MIC) values were determined, and the photodynamic response was further explored in MRSA-infected HT-29 (human colorectal adenocarcinoma) and HUVEC (human umbilical vein endothelial) cell models. While the derivative exhibited dose-dependent antibacterial activity, the light-induced reduction in colony-forming units (CFU) was moderate, remaining below a tenfold (1-log10) under the tested conditions. In cell-based assays, the compound showed detectable dark cytotoxicity,which was further enhanced upon laser irradiation. The photodynamic cytotoxic response was more pronounced in infected HT-29 cells than in infected HUVEC cells, with flow-cytometric profiles consistent with predominantly necrotic/late apoptotic cell-death patterns. These findings indicate that the compound exhibits light-enhanced effects in complex infection models; however, further optimization offormulation, photophysical properties, and light dosimetry is required to improve antimicrobial efficacy and selectivity.eninfo:eu-repo/semantics/openAccessMethicillin-Resistant Staphylococcus AureusMicrobial PathogensDose-Dependent Antibacterial ActivityPhotodynamic InactivationPhotosensitizing PhthalocyanineLaserArticle10.17344/acsi.2025.9638733515521Q4WOS:0018889178000012-s2.0-105051753821PMID: 42839567Q3