Squaraine Dyes for Photodynamic Therapy: Study of Their Cytotoxicity and Genotoxicity in Bacteria and Mammalian Cells¶‡ (original) (raw)
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Photochemistry and Photobiology, 2004
Halogenated squaraine dyes 1 and 2 possess favorable photophysical and in vifro photobiological properties that make these new class of molecules interesting for photodynamic therapeutic applications. For a better understanding of the mechanism of their photobiological activity, we have analyzed the DNA damage and the cytotoxicity induced by these photosensitizers in mammalian cells and cell-free systems in the presence and absence of various additives and scavengers. Both photoactivated squaraines were found to be similar efficient in inducing single-strand breaks (SSB) in cellfree DNA when compared with the cellular DNA. Superoxide dismutase and catalase did not show any influence. However, the presence of tert-butanol and glutathione inhibited the formation of the DNA SSB, indicating an indirect (possibly squaraine radical mediated) mechanism under cell-free conditions. Replacing H 2 0 in the buffer by D20 resulted in a five-to six-fold increase in the number of the SSB in cell-free DNA and a significant enhancement of the photocytotoxicity in mouse lymphoma cells. The results demonstrate that singlet oxygen is the major reactive species under cell-free and cellular conditions and confirm that squaraine-based sensitizers 1 and 2 can have potential applications in photodynamic therapy.
Mutation research, 1977
Under a set of defined experimental conditions, the fluence response of Chinese hamster ovary (CHO) cells to various light sources was studied by measuring single-cell survival and mutation to 6-thioguanine (TG) resistance. Fluorescent white, black, and blue lights were sightly lethal and mutagenic. Sunlamp light was highly lethal and mutagenic, exhibiting these biological effects within 15 sec of exposure under conditions recommended by the manufacturer for human use. Lethal and mutagenic effects were observed after 5 min of sunlight exposure; responses varied with hourly and daily variations in solar radiation. Sunlight-induced TG-resistant variants possessed less than 5% of parental cellular hypoxanthine--guanine phosphoribosyl transferase (HGPRT) enzyme activity, suggesting that the mutation induction occurs at this locus. The cell survival and mutation-induction curves generated by exposure of cells to both sunlamp and sunlight were similar to those obtained by the use of a sta...
Journal of Photochemistry and Photobiology B: Biology, 2008
Photodynamic therapy (PDT) is based on the light-induced activation of a photosensitizer generating highly reactive oxygen species that induce tissue destruction in malignant tissues. The present study was carried out to assess the photosensitizing potential of bis(3,5-diiodo-2,4,6-trihydroxyphenyl)squaraine in PDT trials in vivo. Male Swiss albino mice were divided into five groups. Skin tumor was induced using 7,12-dimethylbenz(a)anthracene -DMBA in the animals of Groups II, III, IV and V, while animals of Group I served as the control. At the completion of 20 weeks of induction, the tumor bearing mice from Group III, IV and V were given an intraperitoneal injection with the squaraine dye (12.5 mg/kg body weight). After 24 h, in the Group IV and V animals, the tumor area was exposed to visible light from a 1000 W halogen lamp. The mice from groups I to IV were sacrificed two weeks after the PDT treatment and the marker enzymes (myeloperoxidase [MPO], b-D-glucuronidase, rhodanese, lactate dehydrogenase [LDH], hexokinase, sialic acid and caspase) were assayed in tumor and normal tissues. Animals from Group V were sacrificed after 90 days of PDT treatment and the above parameters were recorded. Reduction in tumor volume and reversal of biochemical markers to near normal levels were observed in the treatment groups. The study assumes importance as it is the first report on PDT-a novel modality, using a squaraine dye for skin cancer therapy in vivo. The uniqueness of the mode of treatment lies in the selective uptake of squaraine dye by the cancer cells and their selective destruction using PDT without affecting the neighbouring normal cells, which is much advantageous over radiation therapy now frequently used. Also in skin cancer models, the progression/cure can be visualized by the naked eye which is another point of advantage, while seeking new modalities for the treatment of cancer.
Photodynamic activity of different dyes
Laser Physics, 2007
Photodynamic therapy (PDT) is a technique for inducing tissue damage with light irradiation of a drug selectively retained in malignant tissue. Many kinds of compounds are known with photosensitizing properties including dyes, drugs, cosmetics, chemicals, and many natural substances. There are different classes of sensitizers used for medical purposes such as tetrapyrroles (porphyrins and derivatives, chlorophyll, phylloerythrin, phthalocyanines), tricyclic dyes with different meso-atoms (acridine orange, proflavine, riboflavine, methylene blue, fluorescein, eosine, erythrosine, rose bengal), and furocoumarins (psoralen and its methoxyderivatives xanthotoxin, bergaptene). In this work, we performed one comparative cytotoxic study of the photodynamic activity presented by tricyclic dyes (methylene blue, fluorescein and erythrosine) and the commercial Russian photosensitizer Photogem® (hematoporphyrin derivative). For this purpose, three cell lines were used: HEp-2 (tumor cells), VERO and McCoy (nontumor cells), and a yeast strain. The wavelength used for irradiation was 630 nm, the same as used in PDT for medical purposes, since it is in the therapeutic window, i.e., where light can penetrate more into the tissues. The results suggest that Photogem® is more cytotoxic and more photocytotoxic than the studied tricyclic dyes in nontumor and tumor cells. These dyes present less cytotoxicity (around half) in normal cells (dark and light) than in tumor cells. In the experiments with microorganisms, methylene blue presented a better photodynamic effect than Photogem®. These results can be explained by the fact that it is more difficult for Photogem® to penetrate in microorganism membranes than mammalian cell membranes. As for Photogem®, these tricycle dyes present a higher cytotoxicity in tumor cells. These data suggest that methylene blue can be an option in photodynamic inactivation as well as in photodynamic therapy, mainly for superficial lesions.
Traditionally, ultraviolet light (100-400 nm) is considered an exogenous carcinogen while visible light (400-780 nm) is deemed harmless. In this work, a LED irradiation system for in vitro photocytotoxicity testng is described. The LED irradiation system was developed for testing photopharmaceutical drugs, but was used here to determine the basal level response of human cancer cell lines to visible light of different wavelengths, without any photo(chemo)therapeutic. The effects of blue (455 nm, 10.5 mW·cm−2), green (520 nm, 20.9 mW·cm−2), and red light (630 nm, 34.4 mW·cm−2) irradiation was measured for A375 (human malignant melanoma), A431 (human epidermoid carcinoma), A549 (human lung carcinoma), MCF7 (human mammary gland adenocarcinoma), MDA-MB-231 (human mammary gland adenocarcinoma), and U-87 MG (human glioblastoma- grade IV) cell lines. In response to a blue light dose of 19 J·cm−2, three cell lines exhibited a minimal (20%, MDA- MB-231) to moderate (30%, A549 and 60%, A375) reduction in cell viability, compared to dark controls. The other cell lines were not affected. Effective blue light doses that produce a therapeutic response in 50% of the cell population (ED50) compared to dark conditions, were found to be 10.9 and 30.5 J·cm−2 for A375 and A549 cells, respectively. No adverse effects were observed in any of the six cell lines irradiated with a 19 J·cm−2 dose of 520 nm (green) or 630 nm (red) light. The results demonstrate that blue light irradiation can have an effect on the viability of certain human cancer cell types and controls should be used in photopharmaceutical testing, which uses high-energy (blue or violet) visible light activation.
International Journal of Cancer, 1994
The properties of a new photosensitizer, meso-tetrahydroxyphenyl-chlorin (mTHPC), were studied using W9 cells (Chinese-hamster lung fibroblasts). Comparisons were made with 2 other photosensitizers: photofrin II (PII) and meso-tetrahydroxyphenyl-porphyrin (mTHPP). A main advantage of mTHPC is that it has a strong absorption at 652 nm. Maximal cellular uptake of the dye was observed after 24 hr incubation of the cells with the drug. Using a confocal laser-scanning fluorescence microscope, we observed a diffuse distribution of mTHPC in the cytoplasm. Furthermore, the lipophilicity of mTHPC was compared with that of the components of PI1 by means of high-pressure liquid chromatography (HPLC). Absorption and fluorescence spectroscopy indicated that aggregated as well as monomeric mTHPC was bound to the cells. The action spectrum for photo-inactivation of the cells showed that aggregated mTHPC did not contribute significantly to its photosensitizing effects. In the present cellular system, the efficiency of photodynamic therapy (PDT) with mTHPC (cells were irradiated at a wavelength of 652 nm) was higher than with PI1 (irradiation at 630 nm) or with mTHPP (648 nm). The quantum yield for photo-inactivation of cells was smaller for mTHPC than for mTHPP and PII. The addition of I ,3-diphenylisobenzofuran (DPBF) reduced cell inactivation during PDT. Thus, PDT with mTHPC seems to act at least partly via a type4 process. 0 1994 Wiley-Liss, 6~.
Toxicology, 2005
DCB, 3,3 -dichlorobenzidine, is used primarily as an intermediate in the manufacture of diarylide yellow or azo red pigments for printing ink, textile, paint, and plastics. It is also used in tattoo inks. In this article, we investigate light-induced toxicity of DCB in both bacteria and human Jurkat T-cells. DCB itself is not toxic or mutagenic to Salmonella typhimurium TA102, but is photomutagenic at concentrations as low as 2 M and phototoxic at concentrations >100 M when bacteria are exposed to DCB and light at the same time (1.2 J/cm 2 of UVA and 2.1 J/cm 2 of visible light). Furthermore, DCB is both photocytotoxic and photogenotoxic to human Jurkat T-cells. Under a light irradiation dose of 2.3 J/cm 2 of UVA and 4.2 J/cm 2 of visible light, it causes the Jurkat T-cells to become nonviable in a DCB dose-dependent manner and the nonviable cells reaches 60% at DCB concentrations higher than 50 M. At the same time, DNA fragmentation is observed for cells exposed to both DCB and light, determined by single cell gel electrophoresis (alkaline comet assay). As much as 5% (average) DNA fragmentation was observed when exposed to 200 M DCB and light irradiation. This suggests that DCB can penetrate the cell membrane and enter the cell. Upon light activation, DCB in the cells can cause various cellular damages, leading to nonviable Jurkat T-cells. It appears, the nonviable cells are not caused solely by fragmentation of cellular DNA, but by other damages such as to proteins and cell membranes, or DNA alkylation. Therefore, persons exposed to DCB through environmental contamination or through tattoo piercing using DCB-containing inks must not only concern about its toxicity without exposing to light, but also its phototoxicity.
Photodynamic Inactivation of Chinese Hamster Cells
Photochemistry and Photobiology, 1983
Visible light exposures have been shown to kill acriflavine bound Chinese hamster cells. Such killing was enhanced when (a) dye was present in the medium during irradiation and (b) the pH of the medium was 8.5, instead of the normal 7.5 during the exposure. The induced killing could be suppressed by the presence of sodium azide during exposure. The results were taken to indicate that both DNA and non-DNA sites were involved in the cellular inactivation by visible light and that singlet oxygen was involved in the process. MATERIALS AND METHODS Cell culture. The cell line used was Chinese hamster
Journal of Chemistry
The aim of this study is to assess the insights of molecular properties of the xanthene dyes [fluorescein (FL), Rose Bengal (RB), erythrosin B (EB), and eosin Y (EY)] to correlate systematically their photodynamic efficiency as well as their phototoxicity against a carcinoma cell line. The phototoxicity was evaluated by comparing the values of the medium inhibitory concentration (IC50) upon HEp-2 cells with the xanthene corresponding photodynamic activity using the uric acid as a chemical dosimeter and their octanol-water partition coefficient (logP). RB was the more cytotoxic dye against HEp-2 cell line and the most efficient photosensitizer in causing photoxidation of uric acid; nevertheless it was the only one characterized as being hydrophobic among the xanthenes studied here. On the other hand, it was observed that the halogen substituents increased the hydrophilicity and photodynamic activity, consistent with the cytotoxic experiments. Furthermore, the reactivity index parame...
Photochemistry and Cytotoxicity Evaluation of Heptamethinecyanine Near Infrared (NIR) Dyes
International Journal of Molecular Sciences, 2013
The present study investigates the photochemical properties of potential photosensitizers for photodynamic therapy, namely four commercial heptamethinecyanine dyes (IR125, IR780, IR813, IR820). Spectroscopic studies were made by means of laser induced fluorescence and laser flash photolysis in order to obtain fluorescence quantum yields and transient absorption spectra. Fluorescence lifetimes were also determined. The differences encountered were essentially related with the interaction of the sulfonate groups with the solvent, and also regarding the rigidification of the central bridge connecting the two nitrogen-containing heterocyclic groups. Transient absorption studies were performed both in aerated and oxygen free samples, to conclude about the formation of photoisomers and triplet state. For the four dyes under study, a cytotoxic evaluation in the dark and after irradiation was performed using HeLa cells as the model cell line, which revealed significant changes after irradiation mainly in IR125 and IR813 dyes. Confocal microscopy analysis showed that these dyes tend to enter to the intracellular space.