Chemical approach for obtaining a porphyrin bonded to nitro-ruthenium derivative as a promising photosensitizer for enhancing light irradiation therapy

Author(s)

Martin, Matheus Torelli ; Becceneri, Amanda Blanque ; Ford, Peter C. ; da Silva, Roberto Santana

• Document type: Journal article
• Source: Inorganic Chemistry Communications; v. 161, p. 9-pg., 2024-01-31.

Abstract

Porphyrins, which display unique and versatile photochemical and photophysical properties, are widely used as photosensitizers (PS) in Photodynamic Therapy (PDT). Here, we have synthesized and evaluated the photodynamic properties of a new porphyrin complex, {TPyP[Ru(NO2)(bpy)2]4}4+, here designated complex I, where TPyP = 5,10,15,20-tetra(4-pyridyl)porphyrin and bpy = 2,2 ' bipyridine. This complex consists of a porphyrin ring bearing nitro-ruthenium groups coordinated by pyridyl bridges. Upon irradiation at 415 nm, the complex I produced singlet oxygen, 1 Delta g O2 (phi Delta = 0.29), and released NO from its nitro-ruthenium moieties (phi NO = 2.63 x 10-5). The fluorescence quantum yield of complex I (phi f = 4.8 x 10-3) was lower than that of the precursor free porphyrin TPyP (compound II) 5.1 x 10-2) and had a shorter fluorescence lifetime (tau f = 7.4 and 10.0 ns, respectively). The lower fluorescence quantum yield of complex I was expected: the outlying nitro-ruthenium groups promoted non-radiative energy dissipation. As for the triplet lifetime decay, complex I displayed two decay lifetimes (tau T1 = 36 and tau T2 = 722 mu s), shorter than the triplet lifetime of compound II (tau T = 987 mu s). Assays performed with the B16-F10 melanoma cell line showed little cytotoxicity from complex I (0-50 mu M) in the dark. However, under photolysis at 415 nm (4 J cm-2), complex I was highly cytotoxic: IC50 was 0.47 +/- 0.12 mu M. Under the same conditions, cis-[Ru(NO2)(bpy)2(py)]+ (complex III) showed no photocytotoxicity. Therefore, we conclude that the photocytotoxicity of complex I stemmed from the combination of NO release with 1 Delta g O2 production in tumor cells. (AU)

• FAPESP's process: 22/15336-3 - Ruthenium complexes and treatment based on electronic excitation: a mechanistic approach focused on cytotoxic assessment by light irradiation, X-rays and ultrasound in 2D and 3D cancer cell lines
• Grantee: Roberto Santana da Silva
• Support Opportunities: Regular Research Grants
• FAPESP's process: 20/03367-6 - Phototherapy using ruthenium-phthalocyanine complexes as generators of reactive oxygen and nitrogen species: study of the mechanism of action in vitro in different 2D and 3D models of cancer cells
• Grantee: Amanda Blanque Becceneri
• Support Opportunities: Scholarships in Brazil - Post-Doctoral