Selective cytotoxic effects of nitrogen-doped graphene coated mixed iron oxide nanoparticles on HepG2 as a new potential therapeutic approach.

New selective therapeutics are needed for the treatment of hepatocellular carcinoma (HCC), the 7th most common cancer. In this study, we compared the cytotoxic effect induced by the release of pH-dependent iron nanoparticles from nitrogen-doped graphene-coated mixed iron oxide nanoparticles (FexOy/N-GN) with the cytotoxic effect of nitrogen-doped graphene (N-GN) and commercial graphene nanoflakes (GN) in Hepatoma G2 (HepG2) cells and healthy cells. The cytotoxic effect of nanocomposites (2.5-100 ug/ml) on HepG2 and healthy fibroblast (BJ) cells (12-48 h) was measured by Cell Viability assay, and the half maximal inhibitory concentration (IC50) was calculated. After the shortest (12 h) and longest incubation (48 h) incubation periods in HepG2 cells, IC50 values of FexOy/N-GN were calculated as 21.95 to 2.11 µg.mL-1, IC50 values of N-GN were calculated as 39.64 to 26.47 µg.mL-1 and IC50 values of GN were calculated as 49.94 to 29.94, respectively. After 48 h, FexOy/N-GN showed a selectivity index (SI) of 10.80 for HepG2/BJ cells, exceeding the SI of N-GN (1.27) by about 8.5-fold. The high cytotoxicity of FexOy/N-GN was caused by the fact that liver cancer cells have many transferrin receptors and time-dependent pH changes in their microenvironment increase iron release. This indicates the potential of FexOy/N-GN as a new selective therapeutic.

The role of salivary galectin-3 and galectin-9 levels in plaque-induced gingivitis and periodontitis.

Background: This study aimed to compare the salivary galectin-3 and galectin-9 levels in periodontitis, gingivitis, and periodontally healthy patients. Methods: This study included 75 non-smokers who were systemically healthy. The clinical periodontal parameters of each participant were recorded. Individuals with periodontal health, gingivitis, and Stage II or Stage III Grade B periodontitis were allocated to the corresponding study groups (n = 25 each). Saliva samples were obtained from all individuals after they abstained from drinking and eating 1 h before sample collection. The galectin-3 and galectin-9 levels in the saliva were analyzed using enzyme-linked immunosorbent assay. One-way analysis of variance, student's t-test, Spearman correlation, and logistic regression were used for statistical analyses. Results: The galectin-3 and galectin-9 levels were significantly higher in the periodontitis and gingivitis groups than in the healthy group (p < 0.001). The highest galectin-3 and galectin-9 levels were observed in the gingivitis group (p < 0.05). Overall, the galectin-3 levels were significantly higher than the galectin-9 levels in all the groups (p < 0.001). Conclusions: The salivary galectin-3 and galectin-9 levels were high in patients with periodontitis and gingivitis, suggesting that they could be potential biomarkers for periodontal diseases.

Prediction of the proximate analysis parameters of refuse-derived fuel based on deep learning approach.

Determination of proximate characteristics can be achieved using conventional analyses methods that require a certain amount of time. In cement factories, refuse-derived fuel (RDF) is continuously fed to a kiln by a conveyor belt, so even if an inappropriate proximate characteristic is determined, it would be too late to prevent the feeding of RDF to the kiln. To overcome this problem, there is a need for instant measurement of the proximate characteristics (moisture, volatile matter, ash) that enables the feeding to be stopped. In such cases, the deep learning (DL) is a useful method based on the prediction of proximate characteristics. Therefore, in this study, the aim is to estimate the mentioned parameters developed by near-infrared spectroscopy (NIR) combined with deep learning models. For this purpose, the spectrographic measurements taken from RDF samples with an NIR spectrometer, and the results of proximate analysis in a laboratory, were used together as a dataset. A fully convolutional neural network (FCNN) and ResNet were used as a network, and they were trained using images of RDF samples and proximate analysis values. The FCNN model was more successful in prediction studies. According to the FCNN model, the results show that the models in the study can predict the moisture, ash, and volatile matter content of RDF with satisfactory R2 values between 0.979, 0.983, and 0.952.

Implementation of an early warning system with hyperspectral imaging combined with deep learning model for chlorine in refuse derived fuels.

Chlorine content is one of the most important parameters in Refuse Derived Fuels (RDFs) used as a fuel in cement kilns. The main problem with the use of RDF is that chlorine in the waste weakens the cement, increases the risk of corrosion in the kiln and forms toxic gas emissions. Alternative fuels containing high amounts of chlorine, such as plastic waste should be used in limited quantities with the quality of the kiln used and the cement being should be preserved by preparing the appropriate RDF mixture. Analyses conducted on the samples taken before the RDF is given to the furnace are time consuming and costly. Therefore, in this study, the aim is to present a more efficient solution to classify by using chlorine analysis results with hyperspectral imaging and a deep learning model study. For this purpose, a model was created using validated laboratory results and spectral data from samples, the model was tested on a prototype conveyor belt, and was implemented using an online early warning system for high chlorine concentrations. The chlorine content of the RDF samples used in the study ranged from 0.10% to 1.41%, with an average of 0.27%. According to the results, the accuracy, precision, Recall and F1 Score related to the early warning system were found to be 0.8909, 0.8889, 0.8889, 0.8889, respectively. In addition, chlorine measurements were performed at 200, 500 and 1000 mm/s belt speeds and accuracy values of 78.39%, 76.35% and 69.94 %, respectively were obtained.

Application of Multi-Criteria Decision analysis including sustainable indicators for prioritization of public transport system.

Paratransit modes dominate the public transportation industry in the majority of developing countries, especially those in Sub-Saharan Africa. The number of these modes has increased rapidly over the years. Authorities have not yet been able to provide a better alternative for passengers, whose demand is ever-growing. In this research, the main modes of public transport in a Sub-Saharan African city, Kampala, have been studied. Here we used multi-criteria decision-making methods to find out which among the four major public transport modes in Kampala, Uganda, are best from a transportation operator's perspective. The evaluation of alternatives was conducted using Analytic Network Process (ANP) and Elimination Et Choice Translating Reality (ELECTRE III) methods. Both the ANP and the ELECTRE III analysis results demonstrate that alternative "Coaster" is the most appropriate alternative from a public transport operator's point of view. A sensitivity analysis consisting of four different scenarios was considered in the changing of weighting percentages (for benefit, cost, and risk clusters) in the ANP and the ELECTRE III analyses, to show the robustness of the ranking results. According to the sensitivity analysis results, there was no change in the final ranking. The findings of this paper are crucial to policymakers within the transportation sectors of developing countries. Integr Environ Assess Manag 2022;18:25-38. © 2021 SETAC.

Utilization of liquid product through pyrolysis of LDPE and C/LDPE as commercial wax.

In this study, pyrolysis of low-density polyethylene (LDPE) and LDPE with aluminum (C/LDPE) wastes was carried out with different heating rates (5, 10, 20 °C/min) at different temperatures (400, 600, 800 °C). Product yields of LDPE and C/LDPE wastes were compared, and optimum liquid products were analyzed to utilize as commercial waxes for future use. The properties of pyrolyzed wastes was investigated with proximate, elemental analysis, and TGA. The as-produced liquid from pyrolysis of wastes was characterized by different characteristic tools, such as elemental analyses, GC-MS analyses, 1H-NMR tests, FT-IR spectra, the density, melting point, and carbon residue to compare commercial waxes. As a result of pyrolysis, the highest liquid product yield was achieved at 800 °C with 5 °C/min heating rate (85.87%) and at 600 °C with 5 °C/min heating rate (71.3%) for LDPE and C/LDPE, respectively. The results indicated that the derived liquid products are similar to commercial heavy wax.

The effect of energy-saving options on environmental performance of a building: a combination of energy audit-life cycle assessment for a university building.

An energy audit was realized for a building group located on a university campus to measure the environmental sustainability and efficient usage of natural resources. As a result of energy audit, exterior insulation and double-glazing application were came to the front for energy-saving options. Although energy audit provides energy-saving options as output, it is not enough to provide information about how environmental impacts will change if the defined options are used. To determine the improvements in terms of environmental indicators, these options were assessed with life cycle assessment (LCA). LCA was realized for 50 years life span for 1 m3 of the building. CML-IA method was used to conduct LCA analyses. Ecovalue08 was applied as a monetary weighting method since the used CML-IA method has no weighting function. Results show that there are significant improvements (> 5%) on ADPff (11-12.5%) and GWP100 (8.5-9.7%) impacts provided by both of the energy-saving options. Additionally, double glazing would provide a 10.5% improvement on ODP. On the other hand, the exterior insulation application would increase the ODP value of EB by 34%. The impact category of GWP100 is found as the most dominant impact according to Ecovalue08. The ranking of the other impact categories from higher to lower value is HTP, ADPff, and AP.

Decision-making for the selection of different leachate treatment/management methods: the ANP and PROMETHEE approaches.

Municipal solid waste (MSW) landfill leachate is a highly contaminated liquid effluent. Leachate has a complex nature that needs to be appropriately treated before being discharged into the environment. There are various options for leachate treatment. Deciding which option should be applied is a complex process, since it depends on many factors that need to provide a balance between the technical, economic, and environmental aspects of sustainability. Multi-criteria decision-making (MCDM) methods are useful techniques to solve complex problems that cannot be easily solved. In this study, MCDM techniques are used for an evaluation of four different leachate treatment options: recirculation of leachate to a landfill site (A1), combined treatment with municipal wastewater (A2), anaerobic and aerobic sequential treatment (A3), and advanced leachate treatment based on membrane processes (A4). The selection of the most appropriate one, based on the criteria, analytic network process (ANP), and preference ranking organization method for enrichment evaluations (PROMETHEE) methods, was applied as MCDM techniques using the Super Decisions software and D-Sight software, respectively. Both the ANP and the PROMETHEE analysis results demonstrate that option A2 is the most appropriate for all of the decision-makers.

A heating value estimation of refuse derived fuel using the genetic programming model.

Refuse Derived Fuel (RDF) makes an increasingly important contribution to sustainable waste management as an energy source in cement kilns. The most important parameter of RDF in an evaluation of its performance as a fuel is Higher Heating Value (HHV). The two methods of HHV determination are the direct method and the indirect method. The direct method requires the use of a calorimetric bomb and the indirect method requires ultimate or proximate analysis. As in the direct method, the ultimate analysis based indirect method requires the use of specific equipment and a skilled analyst. Most cement plants do not have special equipment. From this point of view, this study aims to predict the HHVs of RDF samples using the results of proximate analysis. Two Genetic Programming (GP) Models, namely GP Model #1 and GP Model #2 are used for the prediction. GP Model #1 denotes a modest nonlinear mapping function used for the prediction of HHVs, whereas GP Model #2 is a more inclusive nonlinear correlation analysis model as an improved version of GP Model #1. To assess the developed models, the test data is simulated and statistical results to the estimation of HHVs are reported as R2 equal to 0.9951 and 0.9988, Root Mean Square Error (RMSE) equal to 1.4126 and 0.6971 and Average Absolute Error (AAE) equal to 0.0543 and 0.0251, for GP Model #1 and GP Model #2, respectively. It can be seen that GP Model #2 may be confidently used for HHV estimation.

Cetuximab and epirubicin HCl-combined application as a possibility to treat both parental and epirubicin HCl-resistant liver cancer cells.

BACKGROUND AND AIMS: Targeted chemotherapeutics such as cetuximab can cause many side effects such as skin toxicity when used in high concentrations. In addition, cancer cells can develop resistance to some of the anticancer agents during treatment. The lack of the desired success in chemotherapy and the development of resistance to chemotherapeutics, such as epirubicin HCl, suggest that there is a need for combined therapies. The combination of targeted chemotherapeutics and conventional chemotherapy drugs may lead to the emergence of new strategies in the treatment of cancer. In this study, cytotoxic, antiproliferative, cell cycle inhibitive, oxidative stress generation, and apoptotic effects and effect mechanisms of cetuximab alone and together with epirubicin HCl on parental liver cancer cells (P-Hep G2) and epirubicin HCl-resistant liver cancer cells (R-Hep G2) were investigated. MATERIALS: Cytotoxic effects of cetuximab alone and with epirubicin-HCl on cells were determined by Cell Titer-Blue® Cell Viability and Lactate Dehydrogenase Activity tests. Cell cycle distributions and apoptosis were detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Cetuximab with epirubicin HCl treatment increased the cytotoxic effect on both cells. Caspase-3/7 activity increased 3 and 1.5 times in comparison with control group in P-Hep G2 and R-Hep G2 cells, respectively, after treating with cetuximab alone, whereas the increase was found to be approximately 4.7 and 2.5 times when cetuximab was treated with epirubicin HCl in P-Hep G2 and R-Hep G2 cells, respectively. Both cetuximab alone and together with epirubicin HCl treatments caused increases in Bax/Bcl-2 ratio in both cells. DISCUSSION: Treatment of cetuximab with epirubicin HCl to P-Hep G2 and R-Hep G2 cells was found to be more effective in cytotoxic effect and inducing apoptosis comparison to cetuximab alone treatment. In addition, combination treatment showed different effects on pro-apoptotic/anti-apoptotic genes expression according to cells drug resistance properties.

Evaluation of cytotoxic, membrane, and DNA damaging effects of Thymus revolutus Célak essential oil on different cancer cells.

BACKGROUND/AIM: In this study, we evaluated Thymus revolutus Célak essential oil and its two main constituents, γ-terpinene and p-cymene, as potential oxidative agents against lung cancer and epidermoid carcinoma cells. MATERIALS AND METHODS: Cell viability assessment was made by CellTiter-Blue1397904493 cell viability and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after treatment with 5-600 µg/mL concentrations of essential oil, γ-terpinene, and p-cymene. Malondialdehyde and 8-hydroxy-2'-deoxyguanosine levels in parental H1299, epirubicin-resistant (drug-resistant) H1299, A549, and A431 cells were also assayed after essential oil, γ-terpinene, and p-cymene had been administered for 24 h. Glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GRx), and glucose 6-phosphate dehydrogenase (G6PD) activities were determined. RESULTS: Parental H1299 cells were found to be more sensitive to the cytotoxic effects of all compounds. While A431 cells had the highest membrane damage, which was caused by essential oil (IC50 and IC70), A549 cells had the highest DNA damage at IC50 and IC70 p-cymene concentrations. G6PD, GST, GRx, and GPx enzyme activities of cells, which increased against these compounds, depended on concentrations, incubation times, and antioxidant capacities of the cells. CONCLUSION: This study suggests that different cancer cells showed different cellular responses against potential antitumor and prooxidative effects of the essential oil and its two main constituents.

Pyrolysis of Plants After Phytoremediation of Contaminated Soil with Lead, Cadmium and Zinc.

The aim of this study was to remediate lead (Pb), cadmium (Cd) and zinc (Zn) from contaminated soil and stabilize to pyrolysis solid product. To accomplish this, phytoremediation of soil contaminated with Pb, Cd and Zn by different plants (sunflower, corn and rape) was performed with and without ethylenediaminetetraacetic acid (EDTA). According to phytoremediation results, rape was the most effective plant with 72 %, 76 % and 77 % removal efficiency for Pb, Cd and Zn, respectively. Also, EDTA addition had no significant effect on translocation of the metals from roots to stems. According to pyrolysis results, Pb, Cd and Zn in the contaminated plants were stabilized in the ash/char fraction. In addition, the solid product can be safely landfilled as inert waste since its toxicity leaching value is lower than the limit values given in the Turkish Regulation on Landfilling of Wastes.

Evaluation of healthcare waste treatment/disposal alternatives by using multi-criteria decision-making techniques.

Healthcare waste should be managed carefully because of infected, pathological, etc. content especially in developing countries. Applied management systems must be the most appropriate solution from a technical, environmental, economic and social point of view. The main objective of this study was to analyse the current status of healthcare waste management in Turkey, and to investigate the most appropriate treatment/disposal option by using different decision-making techniques. For this purpose, five different healthcare waste treatment/disposal alternatives including incineration, microwaving, on-site sterilization, off-site sterilization and landfill were evaluated according to two multi-criteria decision-making techniques: analytic network process (ANP) and ELECTRE. In this context, benefits, costs and risks for the alternatives were taken into consideration. Furthermore, the prioritization and ranking of the alternatives were determined and compared for both methods. According to the comparisons, the off-site sterilization technique was found to be the most appropriate solution in both cases.

A comparative study of the antioxidant/prooxidant effects of carvacrol and thymol at various concentrations on membrane and DNA of parental and drug resistant H1299 cells.

Carvacrol and thymol, both used as flavor agents in cosmetic and food products, have prooxidant and antioxidant activities. To clarify the mechanisms of their cytotoxicity and the factors affecting their antioxidant/prooxidant activities, we investigated cell membrane and DNA damage induced by carvacrol and thymol in parental and drug-resistant human lung cancer cell lines. After 24 and 48 hour incubation periods, the cytotoxicity of carvacrol (IC50 380 and 244 microM) was found to be higher than that of thymol (IC50 497 and 266 microM) in parental cells. However, thymol showed higher cytotoxic effects in drug resistant H1299 cells for three incubation periods. Also, carvacrol and thymol, at higher concentrations, increased malondealdehyde (MDA) levels causing membrane damage and 8-hydroxy deoxyguanozine (8-OHdG) levels, causing DNA damage to both parental and drug resistant cells. On the other hand, carvacrol and thymol protected the cells against H2O2-induced cytotoxicity, and membrane and DNA damage when the cells were preincubated with these two compounds at lower concentration (< IC50) before H2O2 incubation. These findings suggest that carvacrol and thymol exhibit protective/damaging effects depending on cell resistance, concentration and time.

Antioxidant and anticancer activity of fresh corm extract from Romulea tempskyana (Iridaceae).

The antioxidant and anticancer properties of a medicinal plant, Romulea tempskyana (R. tempskyana) (Iridaceae) were investigated. The fresh corm water extract of R. tempskyana significantly increased cell viability against H(2)O(2) cytotoxicity(.) The extract also showed high inhibition of the lipid peroxidation activity (78.20%), reducing power (IC(50) 64.99 µg mL(-1)) activity and hydroxyl (IC(50) 38.66 µg mL(-1)), superoxide (IC(50) 25.99 µg ml(-1)) and DPPH (IC(50) 19.88 µg mL(-1)) radical scavenging activity. On the other hand, treatment of the cells with higher extract concentration showed the anticancer activity inducing cytotoxicity. The extract significantly affected Hepatoma G2 and H1299 cell proliferation (IC(50); 103.79 and 88.15 µg mL(-1)). The amount of MDA (2-fold and 2.5-fold) and activities of several cellular antioxidant enzymes, including Se-GSPx (30%, 15%), non-Se-GSH-Px (11%, 16%) and GST (17%, 23%) increased in Hepatoma G2 and H1299 cells treated with IC(50) concentrations of extract, respectively. These findings suggest that R. tempskyana extract exhibits antioxidant and carcinogenesis-reducing potential.

Life cycle assessment of solid waste management options for Eskisehir, Turkey.

Life cycle assessment (LCA) methodology was used to determine the optimum municipal solid waste (MSW) management strategy for Eskisehir city. Eskisehir is one of the developing cities of Turkey where a total of approximately 750tons/day of waste is generated. An effective MSW management system is needed in this city since the generated MSW is dumped in an unregulated dumping site that has no liner, no biogas capture, etc. Therefore, five different scenarios were developed as alternatives to the current waste management system. Collection and transportation of waste, a material recovery facility (MRF), recycling, composting, incineration and landfilling processes were considered in these scenarios. SimaPro7 libraries were used to obtain background data for the life cycle inventory. One ton of municipal solid waste of Eskisehir was selected as the functional unit. The alternative scenarios were compared through the CML 2000 method and these comparisons were carried out from the abiotic depletion, global warming, human toxicity, acidification, eutrophication and photochemical ozone depletion points of view. According to the comparisons and sensitivity analysis, composting scenario, S3, is the more environmentally preferable alternative. In this study waste management alternatives were investigated only on an environmental point of view. For that reason, it might be supported with other decision-making tools that consider the economic and social effects of solid waste management.

Characterization of an urban landfill soil by using physicochemical analysis and solid phase microextraction (SPME)-GC/MS.

We have aimed at characterizing top soil samples taken in-situ from five different locations of the unregulated dumping site in Eskisehir/Turkey for a period of six months. The study is the first attempt in the city and in Turkey, regarding particularly the SPME (Solid Phase Microextraction Technique) analysis method utilized. A comprehensive research has been conducted to produce critical soil data to be used for indicating current risks as well as the urgency of rehabilitating the site and establishing a sanitary landfill in the site. Conventional physicochemical analytical methods and SPME technique were used to analyze the samples. Physicochemical analyses were performed for determining the pH, total dried matter, volatile matter, total nitrogen, phosphorus, macro elements and heavy metals. Meteorological data were also recorded for the same period. SPSS.10.0 statistical program was used to determine the correlation between meteorological data and physicochemical analysis results. Mean values were used in the correlation analyses. These data indicated that the air temperature and precipitation have significant effects on soil characteristics. SPME, coupled with GC/MS, was used to identify eighty six volatile and semi-volatile organic compounds contained in soil samples. The samples were extracted by headspace SPME with heating (DeltaHS-SPME). SPME analyses were conducted using a commercially available polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber having a film thickness of 65 microm (Supelco) as a capture medium. The experimentally optimized headspace sampling conditions were arranged (15 min. at 50 degrees C) before a 30 min. sampling period.

Characterization of the leachate in an urban landfill by physicochemical analysis and solid phase microextraction-GC/MS.

The aim of this study is to evaluate extensively the characterization and identification of major pollutant parameters by paying attention to the organic chemical pollution for unregulated dumping site leachate in Eskisehir/Turkey. The study that is first and only one research has been very important data related with before new sanitary landfill site in Eskisehir city. For this purpose, in this study leachate samples were collected in-situ at monthly interval for a period of 8 months. Firstly, thirty three physicochemical parameters were monitored. Secondly, SPME technique was used for identification of organic pollutants. Meteorological data were also recorded for the same sampling period to correlate meteorological data and physicochemical parameters. Mean values are used in the correlation analysis. Correlation is shown only for the relationship between air temperature and NO(3) (-). No correlation has been found between rain and leachate quality parameters since the amount of rain was very low during the sampling period. However, analysis results were generally decreased in winter season when each parameter and each sampling point are examined separately. According to correlation between every parameter, especially solid content and dissolved oxygen concentration of leachate is affecting to other parameters. Also, sodium and potassium are changing proportionally with same parameters (suspended solids, fixed solids, dissolved oxygen) and high correlation between chloride and heavy metal concentration is showing. The results were statistically evaluated by use of SPSS 10.0 program. Second part of the study, the leachate was extracted by Solid Phase Microextraction (SPME) technique and then analyzed. Of the methodologies tested in this study, the best one selected was based on 100 micro m polydimethylsiloxane coated fiber (PDMS), headspace with heating (Delta HS) sampling mode and an extraction time of 15 min. at a temperature of 50 degrees C. Thirty three organic compounds in leachate were identified by GC/MS.

Epirubicin HCl toxicity in human-liver derived hepatoma G2 cells.

Epirubicin HCl is a new anthracycline analog and derivative of doxorubicin. Doxorubicin is a potent anticancer agent, the use of which is limited by its cumulative dose-dependent cardiotoxicity. Epirubicin HCl has more favorable therapeutic index than doxorubicin and possesses less hematologic and cardiac toxicity at comparable doses. Hepatoma G2 cells are a valuable model to study hepatocellular carcinoma and the liver, where drugs are metabolized. The goal of our study was to evaluate the cytotoxic effect of epirubicin HCl on viability of Hep G2 cells measured using the MTT cytotoxicity test. Epirubicin HCl produced a concentration- and time-dependent cytotoxicity to Hep G2 cells. The mechanism of cytotoxicity of epirubicin HCl (IC(50) value of 1.6 mug/ml within 24 h) appeared to involve a production of free radical species since activities of free radical scavenging enzymes (SOD, catalase, Se-dependent GPx) were increased. Addition of SOD prevented cytotoxicity of epirubicin HCl, and also counteracted the apoptosis. DNA fragmentation was determined to evaluate apoptosis. Western blot analysis indicated a decrease in GST-pi expression and increased activity of NADPH-dependent cytochrome P450 reductase which is a major enzyme in the conversion of epirubicin HCl to a free radical. It is proposed that production of reactive oxygen species increased by the treatment with epirubicin HCl can cause lipid peroxidation, which subsequently promotes apoptosis and reduces cell viability. Superoxide dismutase, catalase and glutathione peroxidase must be considered as a part of the intracellular antioxidant defense mechanism of Hep G2 cells against single electron reducing quinone-containing anticancer antibiotics.