A comprehensive in-vitro investigation to understand the phototoxic properties of porphyrin derivates on tetrahymena thermophila and basal cell carcinomas

Porphyrins are vital macrocyclic molecules that exist naturally and are significant to the metabolic processes of living organisms. Some of the best-known examples include iron-containing porphyrins in heme and magnesium-containing porphyrins in chlorophyll. These compounds are substantial for life on Earth. Therefore, gaining a deep understanding of porphyrins and their properties is essential for understanding many biological processes.⁶⁹ This research investigates the synthesis, photochemical characterization, and applications of porphyrin derivatives, focusing on their potential in photodynamic therapy. Initially, the synthesis of non-water-soluble Dimethyl-amino-phenylporphyrin (DMAPP) and its transformation into water-soluble derivatives TAPPI₄ (Tetra-p-trimethyl-ammonium-phenyl-porphyrin-tetraiodide) and its metallo derivatives ZnTAPPI₄ (Tetra-(p-trimethyl-ammonium-phenyl) zinc (II)-porphyrin- tetraiodide) and CuTAPPI₄ (Tetra-(p-trimethyl-ammonium-phenyl) copper (II)-porphyrin- tetraiodide) were produced. Comprehensive photochemical analysis revealed unique absorption and emission abilities, aggregation behaviors, and fluorescence lifetimes, suggesting different photostability and reactivity under light exposure with lifetimes measured at 3.26 x 10⁻⁵ seconds for TAPPI₄, 1.49 x 10⁻¹¹ seconds for ZnTAPPI₄, and 3.66 x 10⁻⁹ seconds for CuTAPPI₄. These compounds were then tested in-vitro on tetrahymena thermophila, a unicellular eukaryote, and basal cell carcinoma cells (BCC) from the salivary gland and the lung with the following concentrations: 100 ppm, 50 ppm, 30 ppm, 15 ppm, three ppm, and 0 ppm. Results indicate no dark toxicity except for 100 ppm CuTAPPI₄ and studies showed 90% tetrahymena thermophila cell death within 12h of continuous red-light radiation in 50 ppm TAPPI₄ solutions. Furthermore, studies demonstrated 75% effectiveness on benign salivary gland BCC cells and 94% on malignant lung BCC cells at a concentration of 100ppm TAPPI₄ within 12h of continuous red-light radiation. Finally, Photochemical and photophysical studies included fluorescence quenching of TAPPI₄ with the following quinones: 2,6-dichloro-1,4-benzoquinone, Methyl-p-benzoquinone and Benzoquinone. The quenching constant was established for each quinone and is at kq= 1.36 x 10⁷ L mol⁻¹s⁻¹ for methyl-p-benzoquinone, at kq 3.37 x 10⁶ L mol⁻¹s⁻¹, 2,6-dichloro-1,4-benzoquinone and at kq = 7.41 x 10⁵ L mol⁻¹s⁻¹ for Methyl-p-benzoquinone. This research involves several analytical methods, including UV-Vis absorption spectroscopy, emission spectroscopy, and GC-MS analysis, to characterize reaction products and intermediates.