Self-aggregation of the proteolytic forms of Verteporfin: An in silico and in vitro study

• Published in: Journal of molecular liquids Vol. 352; p. 118640
• Main Authors: Calori, Italo Rodrigo, Braga, Gustavo, Tessaro, André Luiz, Caetano, Wilker, Tedesco, Antonio Claudio, Hioka, Noboru
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2022
• Subjects: Acid organelle; Photodynamic therapy; Photosensitizer; Self-aggregation; Verteporfin; Verteporfin; Acid organelle; Photodynamic therapy; Self-aggregation; Photosensitizer
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.118640

•Self-aggregation of the proteolytic forms of Verteporfin was described.•In water/ethanol mix, self-aggregation follows: neutral > monoanionic > dicationic.•J-type aggregates are formed in high water content medium and inside cells.•Water mostly governs the self-aggregation of Verteporfin inside cells.•No preferential self-aggregation in acid lysosomes of U87MG cells line occurs. Verteporfin is a benzoporphyrin derivative monoacid ring A that has been historically and successfully used as a photosensitizer in clinical applications and in clinical trials including for cancer phototherapy. However, the photo-efficiency of Verteporfin is limited by self-aggregation in water, in which the various proteolytic forms present distinct self-aggregation tendencies. In this work, spectroscopic and computational studies were used to elucidate the self-aggregation behavior of the three proteolytic forms of Verteporfin. Additionally, the intracellular self-aggregation of Verteporfin was evaluated in U87MG cells line, a type of brain cancer considered incurable. The results indicated that the self-aggregation of Verteporfin in water is most likely modulated by formal charge effects following the order: neutral > monoanionic > dicationic. UV–vis electronic spectroscopy and computational dynamics analyses suggested that J-type aggregates were primarily formed. Time-resolved fluorescence and fluorescence lifetime imaging microscopy (FLIM) confirmed that although such aggregates exist in solution and inside cells, there is no evidence of preferential self-aggregation in acidic organelles, such as lysosomes. The present approach allows a better understanding of the self-aggregation of other photosensitizers, particularly the influence of different proteolytic forms and organelles on the self-aggregation of compounds that can be protonated, and the heterogeneity of photosensitizers within intracellular compartments.