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    Hydrophilic vs. amphiphilic anionic Zn(II) phthalocyanines for photodynamic therapy
    (Elsevier, 2025) Al-Hamdan, Nouf S.; Makhseed, Ethar S.; Husain, Ali; Bagda, Efkan; Bagda, Esra; Duman, Didem; Ayhan, Ebubekir
    Two sets of water-soluble zinc (II) phthalocyanines (Zn[II]Pcs) were synthesized and examined for use as photosensitizers in photodynamic therapy. These Zn(II)Pcs contained numerous negatively charged electronwithdrawing carboxylic acid substituents in a rigid arrangement at peripheral positions, subsequently converted into sodium salts. Additionally, the impact of the number and distribution of charged groups on the planar hydrophobic core was examined to assess their influence on the photophysical properties and self-aggregation behavior of the Pcs in an aqueous media. The photophysical findings indicate that the amphiphilic macrocycles (2A, 3A, and 4A) produce more singlet oxygen than the hydrophilic ones (2H, 3H, and 4H) in DMF. The photodynamic activity of sodium salts of Zn(II)Pcs bearing anionic substituents (compounds 4A and 4H) was evaluated in vitro against oral squamous cell carcinoma (SCC-9) and mouse fibroblast (L-929) cell lines to help elucidate the cell death mechanism. The results confirmed that 4A exhibits high selectivity and efficiency in causing phototoxicity, with an IC50 value of around 3.8 mu M. This work provides new insights into the advanced development of dual-directional ZnPc-based photodynamic therapy agents for treating oral squamous cell cancer.
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    Investigation of Interaction of Bismarck Brown Y- Palladium Complex with AS1411 G-quadruplex Aptamer
    (2022) Bağda, Esra; Durak, Rümeysa; Bağda, Efkan; Duman, Didem; Ayhan, Ebubekir
    Increased metabolic activity and metastasis are the main and most known characteristics of cancer cells. Increased activity of the cells results in an increase in the transcription, translation, and replication rate of DNA, hence the probability of the formation of G-quadruplex structures increases. The stabilization or destabilization of G-quadruplex with various ligands may cause disruptions in cell proliferation. So, stabilization or destabilization of these secondary structures is important cancer therapy approach. In the present study, Bismarck brown Y-Pd complex was formed in an easy, one-step mixing method. The spectral characteristics and stoichiometry of the BBY-Pd2 were investigated UV-Vis spectrophotometrically. The interaction of the BBY-Pd2 complex with the AS1411 G-quadruplex structure was investigated with spectrophotometric titration. The binding constants were found as 4.38 (± 1.96) × 104 M-1. The effect of the complex on the G-quadruplex conformation of AS1411 was investigated by using circular dichroism (CD) spectrophotometer. The existence of interactions was further supported by DNA polymerase stop assay using a high-sensitivity LED-induced fluorescence detector Qsep100 capillary gel electrophoresis system.
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    Investigation of Interaction of Bismarck Brown Y- Palladium Complex with AS1411 G-quadruplex Aptamer
    (Miraç OCAK, 2022) Bağda, Esra; Durak, Rümeysa; Bağda, Efkan; Duman, Didem; Ayhan, Ebubekir
    Artan metabolik aktivite ve metastaz, kanser hücrelerinin ana ve en bilinen özellikleridir. Hücrelerin artan aktivitesi, G-dörtlü yapıların oluşumunda artışa neden olur. G-quadruplex'in çeşitli ligandlarla stabilizasyonu veya destabilizasyonu, hücre proliferasyonunda bozulmalara neden olabilir. Dolayısıyla, bu ikincil yapının stabilizasyonu veya destabilizasyonu önemli antikanser ilaç hedefleridir. Bu çalışmada, Bismarck kahverengi Y-Pd kompleksi, kolay, tek aşamalı bir karıştırma yöntemiyle oluşturulmuştur. Kompleksin spektral özellikleri ve stokiyometrisi, Uv-vis spektrofotometrik olarak araştırıldı. 1:2, Bismarck Brown Y-Pd kompleksinin AS1411 G-dörtlü yapı ile etkileşimi spektrofotometrik titrasyon ile araştırıldı. Bağlanma sabitleri hesaplandı ve 4.38 (±1.96) x104 M-1 olarak bulundu. Kompleksin G-dörtlü konformasyon üzerindeki etkisi CD spektroskopisi ile araştırıldı. Etkileşimlerin varlığı, yüksek hassasiyetli LED kaynaklı floresan dedektör Qsep100 kapiler jel elektroforez sistemi kullanılarak DNA polimeraz durdurma testi ile desteklenmiştir.
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    Investigation of Interaction of Bismarck Brown Y-Palladium Complex with AS1411 G-quadruplex Aptamer
    (29.12.2022) Bağda, Esra; Durak, Rumeysa; Bağda, Efkan; Duman, Diğdem; Ayhan, Ebubekir
    Increased metabolic activity and metastasis are the main and most known characteristics of cancer cells. Increased activity of the cells results in an increase in the transcription, translation, and replication rate of DNA, hence the probability of the formation of G-quadruplex structures increases. The stabilization or destabilization of G-quadruplex with various ligands may cause disruptions in cell proliferation. So, stabilization or destabilization of these secondary structures is important cancer therapy approach. In the present study, Bismarck brown Y-Pd complex was formed in an easy, one-step mixing method. The spectral characteristics and stoichiometry of the BBY-Pd2 were investigated UV-Vis spectrophotometrically. The interaction of the BBY-Pd2 complex with the AS1411 G-quadruplex structure was investigated with spectrophotometric titration. The binding constants were found as 4.38 (± 1.96) × 104 M-1 . The effect of the complex on the G-quadruplex conformation of AS1411 was investigated by using circular dichroism (CD) spectrophotometer. The existence of interactions was further supported by DNA polymerase stop assay using a high-sensitivity LED-induced fluorescence detector Qsep100 capillary gel electrophoresis system.
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    Thermodynamic and structural investigation of the interaction of quaternized 2,3-octakis-[(2-mercaptopyridine)phthalocyaninato] copper (II) sulfate (CuPc) with parallel and hybrid type G-quadruplex
    (Wiley, 2024) Sahin, Gamze; Bagda, Esra; Temiz, Ozge Goktug; Bagda, Efkan; Ayhan, Ebubekir; Durmus, Mahmut
    G-quadruplexes are important drug targets and get attention due to their existence in telomere, ribosomal DNA, promoter regions of some oncogenes, and the untranslated regions of mRNA. Due to the biological roles of G-quadruplexes, investigating of the G-quadruplex-small molecule interaction is essential. The primary motivation for these studies is the possibility of inhibiting cell functions associated with G-quadruplex sequences by binding with small molecules. Targeting the small molecules to desired tissue with the G-quadruplex vehicles is the second important goal of the G-quadruplex-small molecule interaction studies. In the present study, the new peripherally 2-mercaptopyridine octasubstituted copper(II) phthalocyanine and its quaternized derivative (CuPc) were synthesized and characterized by elemental analysis FT-IR, UV-Vis, and mass spectra. The excellent solubility of CuPc in water is essential for its transport in the organism. Because of this feature, its affinity toward G-quadruplex forming aptamers, AS1411, Tel21, and Tel45, was investigated. The UV-Vis spectrophotometric titration data confirmed the prevention of aggregation upon interaction with G-quadruplex, which is very important for biomedical applications. The CD spectroscopic analyses and binding stoichiometry confirmed the end stacking model for interaction of AS1411 with CuPc. The interaction of CuPc caused the equilibrium shift from hybrid conformation to antiparallel conformation for Tel21 and Tel45. The isothermal titration calorimeter (ITC) was used for the determination of thermodynamic parameters. The thermodynamic data of the interaction was fitted well with the one-site model. The negative values of Gibbs free energy change confirmed the spontaneous nature of the reactions. Besides, the negative values of enthalpy change and entropy change proved that the nature of processes was enthalpy driven. The interaction stoichiometry was 2 for AS1411 and Tel21 and 1.5 for Tel45. The binding constants were 1.3(+/- 0.3) x 10(5), 3.2(+/- 0.4) x 10(5), and 1.1(+/- 0.3) x 10(5) M-1, which were at the level of ethidium bromide intercalation binding constant given in the literature. The DNA polymerase stop assay further supported the interaction of CuPc with G-quadruplex DNA. The experimental results confirm that the CuPc has a potential photosensitizer behaviour for photodynamic therapy.