Photodynamic evaluation of tetracarboxy-phthalocyanines in model systems

• Published in: Journal of photochemistry and photobiology. B, Biology Biology, 2016-08, Vol.161, p.100-107
• Main Authors: Alonso, Lais, Sampaio, Renato N., Souza, Thalita F.M., Silva, Rodrigo C., Neto, Newton M. Barbosa, Ribeiro, Anderson O., Alonso, Antonio, Gonçalves, Pablo J.
• Format: Article
• Language: English
• Subjects: Animals; Cattle; Dimethyl Sulfoxide - chemistry; Erythrocyte Membrane - chemistry; Hemolysis - radiation effects; Humans; Hydrophobic and Hydrophilic Interactions; Indoles - chemistry; Indoles - pharmacology; Light; Models, Molecular; Organometallic Compounds - chemistry; Organometallic Compounds - pharmacology; Oxidation-Reduction; Photolysis - drug effects; Photolysis - radiation effects; Photosensitizing Agents - chemistry; Photosensitizing Agents - pharmacology; Serum Albumin, Bovine - chemistry; Singlet Oxygen - chemistry; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Water - chemistry
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2016.05.008

The present work reports the synthesis, photophysical and photochemical characterization and photodynamic evaluation of zinc, aluminum and metal free-base tetracarboxy-phthalocyanines (ZnPc, AlPc and FbPc, respectively). To evaluate the possible application of phthalocyanines as a potential photosensitizer the photophysical and photochemical characterization were performed using aqueous (phosphate-buffered solution, PBS) and organic (dimethyl sulfoxide, DMSO) solvents. The relative lipophilicity of the compounds was estimated by the octanol-water partition coefficient and the photodynamic activity evaluated through the photooxidation of a protein and photohemolysis. The photooxidation rate constants (k) were obtained and the hemolytic potential was evaluated by the maximum percentage of hemolysis achieved (Hmax) and the time (t50) to reach 50% of the Hmax. Although these phthalocyanines are all hydrophilic and possess very low affinity for membranes (log PO/W=−2.0), they led to significant photooxidation of bovine serum albumin (BSA) and photohemolysis. Our results show that ZnPc was the most efficient photosensitizer, followed by AlPc and FbPc; this order is the same as the order of the triplet and singlet oxygen quantum yields (ZnPc>AlPc>FbPc). Furthermore, together, the triplet, fluorescence and singlet oxygen quantum yields of zinc tetracarboxy-phthalocyanines suggest their potential for use in theranostic applications, which simultaneously combines photodiagnosis and phototherapy. [Display omitted] •All tetracarboxy-phthalocyanines showed significant photodynamic action.•ZnPc presented higher photodynamic potential followed by AlPc and FbPc.•Photodynamic efficiency of Pcs studied follows the order of triplet quantum yield.•ZnPc shows characteristic that allows be used in theranostic applications.