The Phototoxicity of Fluvastatin, an HMG-CoA Reductase Inhibitor, Is Mediated by the formation of a Benzocarbazole-Like Photoproduct

In this paper, we have investigated the mechanism of phototoxicity of fluvastatin, an 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, in human keratinocytes cell line NCTC-2544. Fluvastatin underwent rapid photodegradation upon Ultraviolet-A (UVA) irradiation in buffered aqueous solution as shown by the changes in absorption spectra. Interestingly, no isosbestic points were observed but only a fast appearance of a spectral change, indicative of the formation of a new chromophore. The isolation and characterization of the main photoproduct revealed the formation of a polycyclic compound with a benzocarbazole-like structure. This product was also evaluated for its phototoxic potential. Cell phototoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide test after 72 h from the irradiation in the presence of fluvastatin. The results showed a reduction of the cell viability in a concentration and UVA dose-dependent manner. Surprisingly, the photoproduct showed a dramatic decrease of the cell viability that occurred at concentrations of an order of magnitude lower than the parent compound. Flow cytometric analysis indicated that fluvastatin and its main photoproduct induced principally necrosis as revealed by the large appearance of propidium iodide-positive cells and confirmed also by the rapid drop in cellular adenosine triphosphate levels. Interestingly, a rapid increase of intracellular calcium followed by an extensive cell lipid membrane peroxidation and a significant oxidation of model proteins were induced by fluvastatin and its photoproduct, suggesting that these compounds exerted their toxic effect mainly in the cellular membranes. On the basis of our results, the phototoxicity of fluvastatin may be mediated by the formation of benzocarbazole-like photoproduct that acts as strong photosensitizer

S-seco-porphyrazine as a new member of the seco-porphyrazine family – Synthesis, characterization and photocytotoxicity against cancer cells

An important subgroup within the porphyrazine (Pz) family constitutes seco-porphyrazines, in the chemical structure of which one pyrrole unit is opened in the oxidative process. So far, there are only limited data on N-seco- and C-seco-Pzs. Here, the synthesis of a novel member of the Pzs seco-family, represented by an S-seco-tribenzoporphyrazine analogue, 22,23-bis(4-(3,5-dibutoxycarbonylphenoxy)butylsulfanyl)tribenzo[b,g,l]-22,23-dioxo-22,23-seco-porphyrazinato magnesium(II), is reported, with moderate 34% yield. The new derivative was characterized using NMR spectroscopy, UV–Vis spectroscopy, and mass spectrometry. In the photochemical study performed following the indirect chemical method with 1,3-diphenylisobenzofuran, S-seco-Pz revealed a high singlet oxygen quantum yield of 0.27 in DMF. Potential photocytotoxicity of S-seco-Pz was assessed in vitro on three cancer cell lines – two oral squamous cell carcinoma cell lines derived from the tongue (CAL 27, HSC-3) and human cervical epithelial adenocarcinoma cells (HeLa). In the biological study, the macrocycle was tested in its free form and after loading into liposomes. It is worth noting that S-seco-Pz was found to be non-toxic in the dark, with cell viability levels over 80%. The photocytotoxic IC50 values for free S-seco-Pz were 0.61, 0.18, and 4.1 µM for CAL 27, HSC-3 and HeLa cells, respectively. Four different liposomal compositions were analyzed, and the cationic liposomes revealed the highest photokilling efficacy, with the IC50 values for CAL 27, HSC-3, and HeLa cells at 0.24, 0.25, and 0.31 µM, respectively. The results of the photocytotoxicity study indicate that the new S-seco-tribenzoporphyrazine can be considered as a potential photosensitizer in photodynamic therapy of cancer, along with the developed cationic liposomal nanocarrier

Photosensitizers based on porphyrin derivatives as a potential photodynamic agent

Photodynamic therapy (PDT) can be defined as the administration of photosensitizer either systemically, locally, or topically to a patient bearing a lesion (frequently but not always cancer), followed after some time by the illumination of the lesion with visible light (usually long wavelength red light). In the presence of molecular oxygen it leads to the generation of cytotoxic species and consequently to cell death and tissue destruction. The singlet oxygen have high reactivity and short half-life. Due to this, PDT directly affects only those biological substrates that are close to the region where these species are generated, usually within a 20 nanometers radius. Therefore, photosensitizers localization is a primary factor in drug release studies to target tissues because it selectivity promotes localized sensitization. In this study, the photosensitive compounds (G0, G1, G2) based on the rings porphyrin were synthesized and characterized (SEM, ATR-IR, NMR, thermal analysis). These molecules were also incorporated into chitosan films. The two step synthesis towards novel macrocycles were elaborated: alkylation reactions and macrocyclization reactions. The photostability of the obtained photosensitizers using high pressure mercury vapour lamp was examined. In the absorption spectra two characteristic bands for the obtained compound are observed: the Soret band located in the range of 300-400 nm and the Q band within 600-800 nm. The amount of produced singlet oxygen at ambient temperature in aerobic conditions was also determined. The lowest value of singlet oxygen quantum yield revealed G0 and the highest revealed G1. The aggregation study was also performed. This phenomenon is well-known especially for phthalocyanines and porphyrin derivatives. The results of the obtained compounds were compared with the results of the commercially available porphyrins. Bibliography: [1] D.P. Ferreiraa, D.S. Conceiçãoa, R.C. Calhelhac, T. Sousaa, Radu Socoteanub, I.C.F.R. Ferreirac, L.F. Vieira Ferreira, Carbohydrate Polymers 2016, 151, 160-171. [2] G.M. Fioramonti Calixto, J. Bernegossi, L. Marise de Freitas, C. R. Fontana, M. Chorilli, Molecules 2016, 21, 342-360. The project was supported by research grant: National Science Centre 2015/19/N/NZ7/0293

Porphyrazines containing styryldiazepine rings and their liposomal formulations: preparation, photochemical properties and photodynamic activity against oral cancer cell lines

Photodynamic therapy (PDT) is a novel, alternative, anticancer treatment, which has also been used to cure cardiovascular, dermatological, and ophthalmic diseases as well as various microbial infections. PDT consists of three factors: compound (photosynthesizer), oxygen, and light. Upon irradiation with light of specific wavelength the photosynthesizer undergoes activation and produces reactive oxygen species such as singlet oxygen. As a consequence, it leads to the death of the treated tissue. Here we present our data to the synthesis of prophyrazines and tribenzoporphyrazines containing styryldiazepine rings. Condensation reactions of known dicyanodiazepins with 3,4,5-trimetoxybenzaldehyde and 1-methyl-2-imidazolecarbaldehyde led to the novel 1,4-diazepine-2,3-dicarbonitriles containing arylvinyl substituents. However, only diazepines with 3,4,5-trimetoxyphenyl groups subjected to macrocyclization reactions gave the desired macrocycles of sufficient stability. Novel macrocyclic compounds were characterized using various spectroscopic methods and extensively investigated in photochemical studies. Moreover, their photodynamic activity was examined in vitro using two human oral squamous cell carcinoma cell lines, HSC-3 cells derived from the tongue and H413 cells from the buccal mucosa. Magnesium tribenzoprophyrazine (Pz1) revealed high activity against cancer cells even at low concentrations and low light dose. Moreover, significantly higher cytotoxicity of Pz1 was observed after its incorporation into negatively charged liposomes

Photosensitizers mediated photodynamic inactivation against virus particles

Viruses cause many diseases in humans from the rather innocent common cold to more serious or chronic, life-threatening infections. The long-term sideeffects, sometimes low effectiveness of standard pharmacotherapy and the emergence of drug resistance require a search for new alternative or complementary antiviral therapeutic approaches. One new approach to inactivate microorganisms is photodynamic antimicrobial chemotherapy (PACT). PACT has evolved as a potential method to inactivate viruses. The great challenge for PACT is to develop a methodology enabling the effective inactivation of viruses while leaving the host cells as untouched as possible. This review aims to provide some main directions of antiviral PACT, taking into account different photosensitizers, which have been widely investigated as potential antiviral agents. In addition, several aspects concerning PACT as a tool to assure viral inactivation in human blood products will be addressed.status: publishe

Cellular changes, molecular pathways and the immune system following photodynamic treatment

Photodynamic therapy (PDT) is a novel medical technique involving three key components: light, a photosensitizer molecule and molecular oxygen, which are essential to achieve the therapeutic effect. There has been great interest in the use of PDT in the treatment of many cancers and skin disorders. Upon irradiation with light of a specific wavelength, the photosensitizer undergoes several reactions resulting in the production of reactive oxygen species (ROS). ROS may react with different biomolecules, causing defects in many cellular structures and biochemical pathways. PDT-mediated tumor destruction in vivo involves cellular mechanisms with photodamage of mitochondria, lysosomes, nuclei, and cell membranes that activate apoptotic, necrotic and autophagic signals, leading to cell death. PDT is capable of changing the tumor microenvironment, thereby diminishing the supply of oxygen, which explains the antiangiogenic effect of PDT. Finally, inflammatory and immune responses play a crucial role in the long-lasting consequences of PDT treatment. This review is focused on the biochemical effects exerted by photodynamic treatment on cell death signaling pathways, destruction of the vasculature, and the activation of the immune system

Liposomal formulations of magnesium sulfanyl tribenzoporphyrazines for the photodynamic therapy of cancer

Photodynamic therapy (PDT) is a treatment that uses light to activate a photosensitizer in the presence of oxygen, leading to the damage of targeted cells by the generation of reactive oxygen species. PDT is used to treat various cancers and cardiovascular, dermatological and ophthalmic diseases as well as different microbial and viral infections. The main drawbacks of currently used photosensitizers, including porphyrinoids, are poor aqueous solubility and the tendency to form aggregates. These issues have been addressed by developing drug delivery systems of which liposomes are considered one of the best and most promising. In this study, previously synthesized dendritic magnesium tribenzoporphyrazineswere incorporatedinto four types of liposome

Current status of liposomal porphyrinoid photosensitizers

The complete eradication of various targets, such as infectious agents or cancer cells, while leaving healthy host cells untouched, is still a great challenge faced in the field of medicine. Photodynamic therapy (PDT) seems to be a promising approach for anticancer treatment, as well as to combat various dermatologic and ophthalmic diseases and microbial infections. The application of liposomes as delivery systems for porphyrinoids has helped overcome many drawbacks of conventional photosensitizers and facilitated the development of novel effective photosensitizers that can be encapsulated in liposomes. The development, preclinical studies and future directions for liposomal delivery of conventional and novel photosensitizers are reviewed. © 2013 Elsevier Ltd. All rights reserved