Genotoxicity and antigenotoxicity evaluation of non-photoactivated hypericin (original) (raw)
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Photoactivated hypericin is not genotoxic
General physiology and biophysics, 2016
The study was designed to test the potential photogenotoxicity of hypericin (HYP) at three different levels: primary DNA damages, gene mutations and chromosome aberrations. Primary genetic changes were detected using the comet assay. The potential mutagenic activity of HYP was assessed using the Ames/Salmonella typhimurium assay. Finally, the ability of photoactivated HYP to induce chromosome aberrations was evaluated by the in vitro mammalian chromosome aberration test and compared to that of non-photoactivated HYP. The results have shown that photoactivated HYP can only induce primary DNA damages (single-strand DNA breaks), acting in a dose-response manner. This activity depended both on HYP concentrations and an intensity of the light energy needed for its photoactivation. However, mutagenic effect of photoactivated HYP evaluated in the Ames assay using three bacterial strains S. typhimurium (TA97, TA98 and TA100) was not confirmed. Moreover, photoactivated HYP in the range of concentrations (0.005-0.01 µg/ml) was not found to be clastogenic against HepG2 cells. Our findings from both the Ames assay and the chromosome aberrations test provide evidence that photoactivated HYP is not genotoxic, which might be of great importance mainly in terms of its use in the photodynamic therapy.
In Vitro Study of the Photocytotoxicity of Some Hypericin Analogs on Different Cell Lines
Photochemistry and Photobiology, 2001
In the present study, hypericin analogs with an increased hydrophilic character were synthesized. As chemical modifications alter the lipophilicity/hydrophilicity balance together with the photophysical/chemical background of the molecule the influence of these structural changes on the cellular uptake, retention and subcellular localization in HeLa cells was investigated. Besides, their photocytotoxic effects using three cell lines (HeLa, MCF-7, A431), as well as their plasma protein binding were also assessed. To assess the relative hydrophilic/lipophilic character of hypericin and analogs their retention times were determined on a reversed phase high performance liquid chromatography (C-18) column. The retention time of all the hypericin analogs was Ͻ46 min, except for dibenzyltetramethylhypericin (118 min), while the retention time of hypericin was Ͼ200 min (solvent system: methanol/citrate buffer 30 mM pH 7; 70/30). Hypericin, hexa-, penta-and dibenzyltetramethylhypericin displayed a potent antiproliferative effect at the nanomolar range after photosensitization (3.6 J/cm 2 ). On the contrary, photoactivated tetrasulfonhypericin and fringelite D had no antiproliferative effect on the three cell lines, whereas hypericin polyethylene glycol showed only an intermediate cytotoxic effect on A431 cells. In dark conditions no antiproliferative effect was observed for any photosensitizer. The antiproliferative photoeffect correlated well with the intracellular accumulation as measured using HeLa cells. In general, the photocytotoxic hypericin analogs concentrated to a large extent, while the noncytotoxic compounds were not taken up by the HeLa cells. Furthermore, confocal laser microscopy re-vealed that all photosensitizers mainly concentrated in the perinuclear region, probably corresponding with Golgi apparatus and the endoplasmic reticulum, except for tetrasulfonhypericin which located at the plasma membrane. In addition, the plasma protein binding studies illustrated that hypericin bind extensively to the lowdensity lipoproteins, while the other hypericin analogs were mainly bound to heavy proteins (mostly albumin) and to a small extent to low-density lipoproteins.
Hypericin Cytotoxicity in Tumor and Non-Tumor Cell Lines: A Chemometric Study
Photodiagnosis and photodynamic therapy, 2017
Hypericin (HY) is an excellent photoactive compound that has been investigated for the photodynamic treatment of cancer as well as for microorganisms inactivation. In this study, chemometric analysis was applied for the first time on photodynamic assays to investigate the cytotoxicity of HY in tumor (HEp-2) and non-tumor (Vero and HUVEC) cell lines. The experimental planning was based on eight assays using the 2(3) full factorial design combining three important variables for PDT: photosensitizer concentrations, incubation time of cells in HY solutions and employed light dose (=590±10nm). The statistical data analysis evidenced the relative significance of such variables and the correlations among them on the cell death. The chemometric results suggested that long incubation time and a low HY concentration and/or light dose allow killing selectively tumor cells. The chemometric analysis could be a new useful empiric method to a previous prediction of the IC50. In this study, the est...
The Multifaceted Photocytotoxic Profile of Hypericin
Molecular Pharmaceutics, 2009
Photodynamic therapy (PDT) is an established anticancer treatment employing a phototoxin (photosensitizer), visible light and oxygen. The latter is photochemically converted into reactive oxygen species, which are highly toxic to the cells. Hypericin, a natural pigment of hypericum plants, is prominent among photosensitizers. The unique perylenequinone structure of hypericin is responsible for its intriguing multifaceted photochemical cytotoxicity. The diverse photodynamic action of hypericin targets a range of subcellular organelles most importantly the mitochondria and the endoplasmic reticulum (ER)-Golgi complex. Hypericin exerts its phototoxicity through intricate mechanisms, implicating key proteins, vital enzymes, organelle membranes and changes in cellular homeostasis. This, depending on drug and light administration conditions, leads to cell death, which occurs mainly by the induction of apoptosis and/or necrosis. Cell photosensitization with hypericin is also associated with the stimulation of macroautophagy, which may promote cell demise when the apoptotic machinery is defective. Herein, we aim to integrate the most important findings with regard to hypericin photocytotoxicity, into a unified scenario, detailing its potential in cancer photomedicine.
Tumor Cell Toxicity of Hypericin and Related Analogs¶
Photochemistry and Photobiology, 2001
A series of hypericin analogs were found to differ in their cytotoxic activity induced by ambient light levels. These analogs vary in their ability to partition into cells, to generate singlet oxygen as well as in other photophysical properties. The data suggest that the biological activity of hypericin is due to a combination of factors whose roles may vary under different circumstances.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 1999
hexamethylcyclopenta-g-2-Ž. benzopyran HHCB , synthetic fragrance ingredients, were evaluated for potential genotoxicity in a battery of short-term tests. Salmonella typhimuriumrEscherichia coli plate incorporation and liquid preincubation assays were conducted on AHTN using tester strains TA97, TA98, TA100, TA102, TA1535, TA1537 and WP2 uÕrA " S9 activation at doses from 8 to 5000 mgrplate. The plate incorporation mutagenicity assay was conducted on HHCB using tester strains TA98, TA100, TA1535, TA1537, TA1538 and WP2 uÕrA " S9 activation at doses from 10 to 5000 mgrplate. An in vitro cytogenetics Ž. assay in Chinese hamster ovary CHO cells was conducted with AHTN and HHCB at three concentrations each with "S9 activation. In the non-activated study, the exposurerharvest periods were 4r20-, 20r20-and 44r44-h. In the S9 activated Ž. study, the exposurerharvest periods were 4r20-and 4r44-h. In vitro unscheduled DNA synthesis UDS assays were conducted in primary rat hepatocytes at concentrations between 0.15 and 50 mgrml for AHTN and HHCB. In vivo mouse micronucleus assays were conducted with high doses of 1600 mg AHTNrkg and of 1500 mg HHCBrkg in corn oil. No positive responses were observed in any of the tests with HHCB. With AHTN, no positive responses were observed except for cells with structural aberrations in the in vitro cytogenetics assay in CHO cells with S9 activation at the treatmentrharvest time of 4r20 h. In initial studies with AHTN, the high dose of 7.8 mgrml showed 0.5% aberrant cells, with the mitotic index at 41% relative to vehicle control and cell growth inhibition in the range of 25-50%. Thus the genotoxicity findings with AHTN were limited to this one positive response; all other genotoxicity tests with AHTN were considered as negative. In particular, the negative finding in the in vivo assay supports AHTN as not likely to be mutagenic in mammalian systems.
Oxygen Dependence of Hypericin-Induced Phototoxicity to EMT6 Mouse Mammary Carcinoma Cells
Photochemistry and Photobiology, 1984
The photodynamic effect of hypericin on EMT6 mouse mammary carcinoma cells was investigated in virro under aerobic and hypoxic conditions. Under aerobic conditions, hypericin-induced photocytotoxicity was dose dependent within a 1-50 p M range. Under hypoxic conditions, cells were resistant to hypericin-induced phototoxicity. In the dark, no cytotoxicity was observed at any hypericin concentration tested either aerobically or hypoxically. Cellular accumulation of hypericin, examined by chemical extraction and spectroscopy, occurred under both hypoxic and aerobic conditions. Fluorescence photomicrographs of cells exposed to hypericin corroborate drug uptake in the plasma membrane and subcellular regions. Our results demonstrate that hypericin cytotoxicity to EMT6 mouse mammary carcinoma cells in virro is both light and oxygen-dependent. These results suggest that EMT6 cell kill caused by photoactivated hypericin is mediated by an oxygen-dependent mechanism, rather than by a type I oxygen-independent mechanism.
Environmental Toxicology and Chemistry, 2006
Chrysene is one of the basic polycyclic aromatic hydrocarbons that are toxic environmental pollutants. The photoproducts of 6-aminochrysene (6AC) include 5,6-chrysenequinone (5,6-CQ) along with some minor products. In this study, cytotoxicity and genotoxicity of 6AC and 5,6-CQ to a human skin cell line, HaCaT, were measured with the fluorescein diacetate uptake (FDA) test and comet assay, respectively, in the presence or absence of ultraviolet A (UVA) irradiation. The FDA test result showed that HaCaT cell viability decreased dose dependently after exposure to UVA irradiation in both 6AC (0, 0.1, 0.5, 1, 5, 10, 50 M) and 5,6-CQ (0, 0.05, 0.25, 0.5, 2.5, 5, 25 M) groups, with the 6AC group having lower cell viability at the same substrate concentrations; therefore, 6AC was more cytotoxic. Results of the comet assay showed that the extent of DNA damage was also dose dependent after the combined UVA and 6AC treatment (0, 0.05, 0.1, 0.5, 1 M), although no DNA damage was detectable in the 6AC group without UVA irradiation. In addition, no DNA damage was found in the 5,6-CQ group with or without UVA irradiation. Our study indicated that 5,6-CQ, the major photoproduct of 6AC, was less photocytotoxic than the parent compound and was not photogenotoxic to HaCaT cells under the experimental conditions.
The effect of quercetin on light-induced cytotoxicity of hypericin
Physiological research / Academia Scientiarum Bohemoslovaca, 2001
Protective effect of quercetin, a natural antioxidant compound, on hypericin-induced cytotoxicity was studied in human promyelocytic leukemia cells (HL-60). Hypericin (10(-5) mol x l(-1)) alone significantly decreased cell survival to 21% that found in the controls, whereas in combination with quercetin (10(-5) mol x l(-1)) this decrease was diminished to 46%. Lower concentrations of quercetin had no protective effect. These findings indicate that oxygen radicals can play an important role in hypericin-induced phototoxic effects.