Genotoxic and antioxidant activities of ethoxyquin salts evaluated by the comet assay

Four newly synthesized salts of ethoxyquin (EQ: 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline), an antioxidant used in animal feeds, were evaluated with the use of the comet assay performed on human lymphocytes: ethoxyquin ascorbate, ethoxyquin hexanoate, ethoxyquin salicylate and ethoxyquin salt of Trolox C (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid). In the study the abilities of these compounds to cause DNA fragmentation and to protect against H2O2-induced DNA damage were analysed. The obtained results were compared with those noted earlier for EQ. After EQ salts treatments (1-25 microM) the genotoxic effects were observed, but the genotoxic potentials of the compounds studied were lower than that of EQ. On the other hand, EQ salts, similarly to EQ, effectively protected the cells from oxidative effect of H2O2. EQ hexanoate was the most effective and its antioxidant activity was even slightly higher than that of EQ. We suggest that it is worth further detailed studies to estimate its usefulness as a preservative.     

In vitro genotoxic effects of ZnO nanomaterials in human peripheral lymphocytes

In this study, possible genotoxic effects of zinc oxide (ZnO) nanoparticles were investigated in cultured human peripheral lymphocytes by using chromosome aberrations and micronucleus assays (MN). For this purpose, the cells were treated with ZnO (1, 2, 5, 10, 15 and 20 μg/mL) for 24 and 48 h. In this research, four types of chromosome aberrations were observed as chromatid and chromosome breaks, fragment and dicentric chromosomes. ZnO induced significant increase of the ratio of chromosomal aberrations as well as percentage of abnormal cells at concentrations of 1, 5, 10 and 20 μg/mL in 24 h treatments. In 48 h treatments, while ZnO nanomaterials induced significant increase of the percentage of abnormal cells only at a concentration of 10 μg/mL, and of chromosome aberration per cell in comparison to the control at concentrations of 5 and 10 μg/mL. On the other hand, this material significantly increased the micronuclei frequency (MN) at concentrations of 10 and 15 μg/mL in comparison to the control. Cytokinesis-block proliferation index was not affected by ZnO treatments. It also decreased the mitotic index in all concentrations at 24 h but not at 48 h. The present results indicate that ZnO nanoparticles are clastogenic, mutagenic and cytotoxic to human lymphocytes in vitro at specific concentrations and time periods.     

Effects of tannic acid and its related compounds on food mutagens or hydrogen peroxide-induced DNA strands breaks in human lymphocytes

The effect of tannic acid (TA), gallic acid (GA), propyl gallate (PA) and ellagic acid (EA) on DNA damage in human lymphocytes induced by food mutagens [3-amino-1-methyl-5H-pyrido (4,3-b) indole (Trp-P-2) and 2-amino-1-methyl-6-phenylimadazo (4,5-b) pyridine (PhIP) or H₂O₂ was evaluated by using single-cell electrophoresis (comet assay). The toxicity of these tested compounds (0.1–100 μg/ml) on lymphocytes was not found. These compounds did not cause DNA strand breaks at lower concentrations of 0.1–10 μg/ml. At a concentration of 100 μg/ml, TA and GA exhibited slight DNA damage, whereas PA and EA showed no DNA strand breaks. TA and its related compounds decreased the DNA strand breaks induced by Trp-P-2, PhIP or H₂O₂ at concentrations of 0.1–10 μg/ml. DNA repair enzymes endonuclease III (Endo III) and formamidopyrimidine-DNA glycoslase (FPG)] were used to examine the levels of oxidised pyrimidines and purines in human lymphocytes induced by H₂O₂. All the compounds at 10 μg/ml can reduce the level of FPG sensitive sites. However, only EA inhibited the formation of EndoIII sensitive sites. The results indicated that these compounds can enhance lymphocytes resistance towards DNA strand breaks induced by food mutagens or H₂O₂ in vitro.     

Evaluation of cytological and genetic effects of Tribulus terrestris fruit aqueous extract on cultured human lymphocytes

The current study was carried out to evaluate the genotoxic aspects of the aqueous extracts of the Tribulus terrestris fruits by comet assay and cytogenetic procedures conditions on cultured human peripheral blood lymphocyte. After the treatment of the lymphocytes with four concentrations of the aqueous fruit extract of T. terrestris (10, 20, 40 and 80 mg/L) for 24 h it was noticed that, the presence of micronuclei and/or chromosomal aberration were monitored and a significant increase of comet cells at high concentration of T. terrestris extract 80 mg/L. Also, this study showed that the presence of micronuclei, chromosomal aberration as a chromosomal gap, fragmentation, stickiness and necrotic cells were appeared and increased with high concentrations of T. terrestris fruits extract (40–80 mg/L). On the other hand, no significant difference was observed with the low concentration of the extract (10–20 mg/L) as compared with control. The current study refers to the ability of the extract of T. terrestris fruits to do damage in the target DNA at the higher concentrations. Thus, it could be considered that the aqueous extracts of the T. terrestris fruits have genotoxic effect in the therapeutic protocols if it used in high doses.     

Modulation of cellular defense processes in human lymphocytes in vitro by a 1,4-dihydropyridine derivative

The aim of this pilot study was to assess whether a compound of the β-carbonyl-1,4-dihydropyridine series (AV-153 or sodium 3,5-bis-ethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine-4-carboxylate), which has high efficiency in stimulating DNA repair, can simultaneously modulate apoptosis in human cells. Peripheral blood lymphocytes of healthy donors were used in this study. DNA strand-break rejoining was assessed with the alkaline comet assay after a 3-h incubation of lymphocytes in the presence of a wide range of concentrations of AV-153 (10⁻¹⁰–10⁻⁵ M). Apoptotic and micronucleated (MN) cells were scored in phytohaemagglutinin-stimulated lymphocytes after a 72-h incubation with AV-153, using the standard cytokinesis-blocked micronucleus test. The study revealed dual effects of AV-153 on cellular defense systems against endogenously generated DNA damage: the compound per se simultaneously reduces DNA strand breaks and stimulates apoptosis, with a maximal efficiency of 76% and 42%, respectively; in contrast, after genotoxic stress (2 Gy of gamma-radiation) AV-153 reduces DNA strand breaks, the number of MN cells and apoptotic cells in a similar dose-dependent manner. A maximal efficiency of 67% was found for reduction of DNA strand breaks, while for MN cells and apoptotic cells the efficiencies were, respectively, 47% and 44%. While limited in number, these preliminary studies show the direct correlation between the efficiency of AV-153 in reduction of radiation-induced DNA breaks and MN cells on one side, and in reduction of apoptosis on the other. It suggests that the major target of the compound's action on genotoxic stress is DNA repair, followed by reduction of the number of damaged cells entering apoptosis.     

Evaluation of antigenotoxicity effects of umbelliprenin on human peripheral lymphocytes exposed to oxidative stress

The protective properties of a prenylated coumarin, umbelliprenin (UMB), on the human lymphocytes DNA lesions were tested. Lymphocytes were isolated from blood samples taken from healthy volunteers. DNA breaks and resistance to H₂O₂-induced damage were measured using a single-cell microgel electrophoresis technique under alkaline conditions (comet assay). Human lymphocytes were incubated in UMB (10, 25, 50, 100, 200, and 400 μM) alone or a combination of different concentrations of UMB (10, 25, 50, 100, 200, and 400 μM) and 25 μM H₂O₂. Untreated cells, ascorbic acid (AA; 25, 50, 100, 200, and 400 μM) and H₂O₂ (25 μM) were considered as negative control, positive control, and the standard antioxidant agent for our study, respectively. Single cells were analyzed with “TriTek Cometscore version 1.5” software. The DNA damage was expressed as percent tail DNA. UMB exhibited a concentration-dependent increase in protection activity against DNA damage induced by 25 μM H₂O₂ (from 67.28% to 39.17%). The antigenotoxic activity of AA, in the range 0–50 μM, was greater than that of UMB. However, no significant difference (p > 0.05) in the protective activity was found between UMB and AA at concentrations of approximately higher than 50 μM.     

Effects of diethylstilbestrol in human lymphocytes in vitro: A dose and time-dependent study on genotoxic, cytotoxic and apoptotic effects

Most of the biological, chemical or physical agents that cause cell death in certain doses and time of exposure may induce either apoptosis or necrosis. This study explores in what ways the genotoxic, cytotoxic and apoptotic effects of diethylstilbestrol (DES), a chemical agent currently used in the treatment of various types of cancer, on the human lymphocytes depend upon the dose and the exposure time. For this purpose, firstly it aims to determine in what dosages and durations of DES treatment, genotoxicity and cytotoxicity in human lymphocytes occur in vitro. Secondly, it explores the effects of DES on sister-chromatid exchanges (SCEs) and apoptosis and their relation with the nitric oxide (NO) levels. Finally, it investigates whether different dosages of DES and duration of treatment with it are correlated with each other. In so doing, we investigated the relationship among the viability, necrosis and apoptosis rates of human lymphocytes which were treated with five different DES concentrations (1, 5, 10, 15 and 20 μM) for 24, 48 and 72 h, DNA fragmentation analysis of these cells, their mean SCE values and NO levels. We concluded that 5 μM DES at 24 h is the most effective dosage that induces typical features of apoptosis in human lymphocytes. Despite the fact that there are many other studies on the effects of DES on the cancer cells, we thought it might be worth looking into the effects of DES on human lymphocytes in vitro. We meant the present study to contribute to the research done in the field of cancer treatment. (Mol Cell Biochem 276: 45–53, 2005)     

Interindividual differences in initial DNA repair capacity when evaluating H<Subscript>2</Subscript>O<Subscript>2</Subscript>-induced DNA damage in extended-term cultures of human lymphocytes using the comet assay

It has been suggested that extended-term cultures of human lymphocytes could be used as a complement to cell lines based on transformed cells when testing the genotoxicity of chemicals. To investigate whether the pattern of induced DNA damage and its subsequent repair differs significantly between cultures based on different blood donors, hydrogen peroxide (H₂O₂)-induced DNA damage was measured in cultures from four different subjects using the comet assay. The DNA damage was significantly increased in all cultures after 10 min exposure to 0.25 mmol/L H₂O₂, and there was a significant decrease in the H₂O₂-induced DNA damage in all cultures after 30 min of DNA repair. The level of damage varied between the different donors, especially after the repair. Using PCR and DNA sequencing, exon 5 of the p53 gene was sequenced in the lymphocytes from the donors with the lowest and highest residual damage. No such mutation was found. Mouse lymphoma L5178Y cells carrying the p53 mutation in exon 5 were included as a reference. These cells were found to be less sensitive toward the H₂O₂-induced DNA damage, and they were also found to have a rather low DNA repair capacity. The demonstrated variation in H₂O₂-induced DNA damage and DNA repair capacity between the cultures from the different subjects may be important from a risk assessment perspective, but is obviously not of decisive importance when it comes to the development of a routine assay for genotoxicity.     

Comparison of micronuclei frequencies in mono-, bi- and poly-nucleated lymphocytes from subjects of a residential suburb and subjects living near a metallurgical plant

Spontaneous baseline frequencies of micronuclei in mono-, bi- and poly-nucleated lymphocytes were analyzed, using the cytokinesis-block technique, in 103 subjects living in a residential suburb (Genova-Nervi), and in 203 subjects living in an urban industrialized area near a metallurgical plant and a coke factory (Genova-Cornigliano). Statistical analysis showed that the average frequency of micronucleated binucleated lymphocytes (MnBNL) was significantly higher (1.42-fold) in donors of Nervi than in donors of Cornigliano living in a contaminated environment. In contrast, the average frequency of micronucleated polynucleated lymphocytes (MnPNL) was significantly higher (1.66-fold) in donors of Cornigliano than in donors of Nervi. The existence in the whole population examined of a positive correlation between frequency of MnBNL and frequency of MnPNL and the absence of a positive correlation between frequency of bi- and poly-nucleated lymphocytes and frequency of MnPNL suggest that the formation of MnPNL is a consequence of genetic damage and not of mitotic errors arising during the division of bi- and poly-nucleated cells. In agreement with previous findings the frequency of MnBNL increased with age and was significantly higher in females than in males; unexpectedly it was higher in non-smokers/non-drinkers than in smokers/drinkers.     

The formation of DNA single-strand breaks and alkali-labile sites in human blood lymphocytes exposed to 365-nm UVA radiation

The potency of UVA radiation, representing 90% of solar UV light reaching the earth׳s surface, to induce human skin cancer is the subject of continuing controversy. This study was undertaken to investigate the role of reactive oxygen species in DNA damage produced by the exposure of human cells to UVA radiation. This knowledge is important for better understanding of UV-induced carcinogenesis. We measured DNA single-strand breaks and alkali-labile sites in human lymphocytes exposed ex vivo to various doses of 365-nm UV photons compared to X-rays and hydrogen peroxide using the comet assay. We demonstrated that the UVA-induced DNA damage increased in a linear dose-dependent manner. The rate of DNA single-strand breaks and alkali-labile sites after exposure to 1 J/cm² was similar to the rate induced by exposure to 1 Gy of X-rays or 25 μM hydrogen peroxide. The presence of either the hydroxyl radical scavenger dimethyl sulfoxide or the singlet oxygen quencher sodium azide resulted in a significant reduction in the UVA-induced DNA damage, suggesting a role for these reactive oxygen species in mediating UVA-induced DNA single-strand breaks and alkali-labile sites. We also showed that chromatin relaxation due to hypertonic conditions resulted in increased damage in both untreated and UVA-treated cells. The effect was the most significant in the presence of 0.5 M Na⁺, implying a role for histone H1. Our data suggest that the majority of DNA single-strand breaks and alkali-labile sites after exposure of human lymphocytes to UVA are produced by reactive oxygen species (the hydroxyl radical and singlet oxygen) and that the state of chromatin may substantially contribute to the outcome of such exposures.     

Protective effects of ursolic acid and oleanolic acid in leukemic cells

Ursolic acid (UA) and oleanolic acid (OA) have similar chemical structures but differ in the position of one methyl group on the ring E. We investigated protective effects of these two triterpenoic acids against H₂O₂-induced DNA damage in leukemic L1210, K562 and HL-60 cells using single-cell gel electrophoresis (SCGE). We compared their protective effects (antioxidant activities) with respect to the different position of the methyl group in their chemical structures. After 24 h pre-treatment of cells both compounds investigated inhibited significantly the incidence of DNA single strand breaks induced by H₂O₂. The concentration range of UA and OA was in all experiments 2.5–10 μmol/l. The antioxidant activity of OA determined by SCGE was significantly higher compared to UA in L1210 (⁺P < 0.05) and K562 cells (⁺⁺⁺P < 0.001). Significant difference of the antioxidant activities of the two compounds was evidently connected with the different position of the methyl group. The protective effect of OA was in HL-60 cells slightly lower compared to the activity of UA, but the difference between the protective effects of UA and OA was not significant. In conclusion we can say that both natural pentacyclic triterpenoic acids investigated, UA and OA, manifested potent antioxidant effects. The different position of one methyl group in their chemical structures caused moderately different biological activities of these compounds on three leukemic cell lines. To explore their mechanisms of action further investigation seems to be therefore worthwhile.     

DNA protecting and genotoxic effects of olive oil related components in cells exposed to hydrogen peroxide

In search for compounds, able to protect nuclear DNA in cells exposed to oxidative stress, extracts from olive leaves, olive fruits, olive oil and olive mill waste water were tested by using the “single cell gel electrophoresis” methodology (comet assay). Jurkat cells in culture were exposed to continuously generated hydrogen peroxide (11.8±1.5 μM per min) by direct addition into the growth medium of the appropriate amount of the enzyme “glucose oxidase” in the presence or absence of the tested total extracts. The protective effects of the tested extracts or isolated compounds were evaluated from their ability to decrease hydrogen peroxide-induced formation of single strand breaks in the nuclear DNA, while the toxic effects were estimated from the increase of DNA damage when the extracts or isolated compounds were incubated directly with the cells. Significant protection was observed in extracts from olive oil and olive mill waste water. However, above a concentration of 100 μg/ml olive oil extracts exerted DNA damaging effects by themselves in the absence of any H₂O₂. Extracts from olive leaves and olive fruits although protective, were also able to induce DNA damage by themselves. Main compounds isolated from the above described total extracts, like oleuropein glucoside, tyrosol, hydroxytyrosol and caffeic acid, were tested in the same experimental system and found to exert cytotoxic (oleuropein glucoside), no effect (tyrosol) or protective effects (hydroxytyrosol and caffeic acid). In conclusion, cytoprotective as well as cytotoxic compounds with potential pharmaceutical properties were detected in extracts from olive oil related sources by using the comet assay methodology.     

Cytotoxic and genotoxic effects of tambjamine D, an alkaloid isolated from the nudibranch Tambja eliora, on Chinese hamster lung fibroblasts

Marine organisms have been shown to be potential sources of bioactive compounds with pharmaceutical applications. Previous chemical investigation of the nudibranch Tambja eliora led to the isolation of the alkaloid tambjamine D. Tambjamines have been isolated from marine sources and belong to the family of 4-methoxypyrrolic-derived natural products, which display promising immunosuppressive and cytotoxic properties. Their ability to intercalate DNA and their pro-oxidant activity may be related to some of the biological effects of the 4-methoxypyrrolic alkaloids. The aim of the present investigation was to determine the cytotoxic, pro-oxidant and genotoxic properties of tambjamine D in V79 Chinese hamster lung fibroblast cells. Tambjamine D displayed a potent cytotoxic effect in V79 cells (IC50 1.2 microg/mL) evaluated by the MTT assay. Based on the MTT result, V79 cells were treated with different concentrations of tambjamine D (0.6, 1.2, 2.4 and 4.8 microg/mL). After 24h, tambjamine D reduced the number of viable cells in a concentration-dependent way at all concentrations tested, assessed by the trypan blue dye exclusion test. The hemolytic assay showed that the cytotoxic activity of tambjamine D was not related to membrane disruption (EC50>100 microg/mL). Tambjamine D increased the number of apoptotic cells in a concentration-dependent manner at all concentrations tested according to acridine orange/ethidium bromide staining, showing that the alkaloid cytotoxic effect was related to the induction of apoptosis. MTT reduction was stimulated by tambjamine D, which may indicate the generation of reactive oxygen species. Accordingly, treatment of cells with tambjamine D increased nitrite/nitrate at all concentrations and TBARS production starting at the concentration corresponding to the IC50. Tambjamine D, also, induced DNA strand breaks and increased the micronucleus cell frequency as evaluated by comet and micronucleus tests, respectively, at all concentrations evaluated, showing a genotoxic risk induced by tambjamine D.     

Cytotoxic and genotoxic effects of sodium hypochlorite on human peripheral lymphocytes in vitro

Chlorination is widely used method in the disinfection of drinking and utility water worldwide. In this study, cytotoxic and genotoxic effects of sodium hypochlorite were investigated by the cytokinesis-block micronucleus assay and chromosomal aberration analysis on human peripheral lymphocytes in vitro. A significant increase in chromosomal aberration frequency was observed in all treatments of NaOCl (0.030, 0.065, 0.100, 0.25, 0.5, 1, 2, 4 μg/mL) at 24 and 48 h compared with the negative control and mitomycin C (MMC, 0.3 μg/mL), which was used as a positive control. NaOCl significantly increased the frequency of micronuclei in a dose dependent manner. The results showed that there was a significant correlation between NaOCl concentration and chromosomal aberration, micronuclei frequency, necrotic cells, apoptotic cells and binucleated cells.     

Effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced oxidative DNA damage (strand breaks and oxidized purines/pyrimidines) in human hepatoma cells

The aim of this study was to evaluate the effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced DNA damage (DNA strand breaks and oxidized purines/pyrimidines) in human hepatoma cells (HepG2), using the Comet assay. Treatment with hydrogen peroxide (H(2)O(2)) increased the levels of DNA strand breaks and oxidized purine and pyrimidine bases, in a concentration and time dependent manner. Organosulfur compounds (OSCs) reduced DNA strand breaks induced by H(2)O(2). In addition, OSCs also decreased the levels of oxidized pyrimidines. However, none of the OSCs tested reduced the levels of oxidized purines. Isothiocyanates compounds (ITCs) and vitamin C showed protective effects towards H(2)O(2)-induced DNA strand breaks and oxidized purine and pyrimidine bases. The results indicate that removal of oxidized purine and pyrimidine bases by ITCs was more efficient than by OSCs and vitamin C. Our findings suggest that OSCs, ITCs and vitamin C could exert their protective effects towards H(2)O(2)-induced DNA strand breaks and oxidative DNA damage by the free radical-scavenging efficiency of these compounds.     

The effects of boric acid on sister chromatid exchanges and chromosome aberrations in cultured human lymphocytes

The aim of this study was to determine the possible genotoxic effects of boric acid (BA) (E284), which is used as an antimicrobial agent in food, by using sister chromatid exchange (SCEs) and chromosome aberration (CAs) tests in human peripheral lymphocytes. The human lymphocytes were treated with 400, 600, 800, and 1000 μg/mL concentrations of BA dissolved in dimethyl sulfoxide (DMSO), for 24 h and 48 h treatment periods. BA did not increase the SCEs for all the concentrations and treatment periods when compared to control and solvent control (DMSO). BA induced structural and total CAs at all the tested concentrations for 24 and 48 h treatment periods. The induction of the total CAs was dose dependent for the 24 h treatment period. However, BA did not cause numerical CAs. BA showed a cytotoxic effect by decreasing the replication index (RI) and mitotic index (MI). BA decreased the MI in a dose-dependent manner for the 24 h treatment period.     

Cytotoxic effects of new trans-2,4-diaryl-r-3-methyl-1,2,3,4-tetrahydroquinolines and their interaction with antitumoral drugs gemcitabine and paclitaxel on cellular lines of human breast cancer

Two tetrahydroquinoline compounds, called DM8 and DM12, from a new series of the cis-2,4-diaryl-r-3-methyl-1,2,3,4-tetrahydroquinolines, were selected for cytotoxic effects studies on cellular lines of human breast cancer. The synergistic, additive and antagonistic effects in combination of these compounds with anticancer drugs, such as paclitaxel and gemcitabine, were studied. The isobolograms and their analysis demonstrated models of synergism, additivity and antagonism of these tetrahydroquinolines in the presence of paclitaxel and gemcitabine. Results showed that compounds DM8 and DM12 individually induced growth inhibition on breast cancer cell lines MCF-7 and SKBR3, and the addition of paclitaxel and gemcitabine intensified their cytotoxic activity on both cell lines at conc. below 1 μg/mL. During these studies the compound DM12 was identified as new, perspective and safe agent for adjuvant therapy.     

Effects of progesterone and estradiol on the proliferation of phytohemagglutinin-stimulated human lymphocytes

In this paper we report on a study to elucidate whether the response of human lymphocytes to mitogenic stimulation was modified by physiological changes which occur during the menstrual cycle. Experiments with untreated cultures showed intra-individual variation to mitogen stimulation in female lymphocyte cultures, but a significant correlation between the menstrual cycle and the proliferation kinetics of lymphocytes was not found. Consequently, we performed experiments in which two of the hormones that regulate the menstrual cycle in women, estradiol and progesterone, were added to cultured human lymphocytes obtained from both men and women. The results indicate that both hormones at physiological concentrations have the capacity to modify the proliferation of PHA-stimulated human lymphocytes. Therefore, both hormones could play a role in the induction of the intra-individual variation observed in the untreated female cultures. However, in vivo other factors could also modify the proliferation kinetics of human lymphocytes preventing the demonstration of the effects of a single factor, such as the hormonal changes occurring during the menstrual cycle.     

The effects of 4-thujanol on chromosome aberrations,sister chromatid exchanges and micronucleus in human peripheral blood lymphocytes

4-Thujanol, a bicyclic monoterpene alcohol, is present in the essential oils of many medicinal and aromatic plants. It is commonly used as a fragrance and flavouring ingredient in a lot of different products. The potential genotoxic effects of 4-thujanol on human peripheral blood lymphocytes (PBLs) were investigated in vitro by the chromosome aberrations (CAs), sister chromatid exchanges (SCEs), and micronucleus (MN) tests. The cells were treated with 13, 26 and 52 μg/mL 4-thujanol in the presence and absence of a metabolic activator (S9 mix). 4-Thujanol induced CA (P < 0.001) and MN formation (P < 0.05) at all concentrations (13, 26 and 52 μg/mL) in the presence and absence of the S9 mix without a concentration-dependent manner. However, the treatment of peripheral lymphocytes with 4-thujanol did not produce a statistical difference in the frequency of SCEs when compared with control group. Furthermore, this monoterpene did not significantly decrease the mitotic index (MI), proliferation index (PI), and nuclear division index (NDI). In conclusion, 4-thujanol had a significant clastogenic effect at the tested concentrations (13, 26 and 52 μg/mL) for human PBLs. In addition, no cytotoxic and/or cytostatic effects were observed regardless of the concentrations used. This work presents the first report on genotoxic properties of 4-thujanol.     

The protective effects of nutritional antioxidant therapy on Ehrlich solid tumor-bearing mice depend on the type of antioxidant therapy chosen: histology, genotoxicity and hematology evaluations

Strong evidence indicates that reactive oxygen species (ROS) play an important role in the initiation as well as the promotion phase of carcinogenesis. Studies support the role of ROS in cancer, in part, by showing that dietary antioxidants act as cancer-preventive agents. Although results are promising, the research on this topic is still controversial. Thus, the aim of this study was to investigate whether vitamins C, E and pequi oil can, individually, provide prevention and/or be used afterward as an adjuvant in cancer therapy. Ehrlich solid tumor-bearing mice received antioxidant as follows: before tumor inoculation, before and after tumor inoculation (continuous administration), and after tumor inoculation; morphometric analyses of tumor, genotoxicity and hematology were then carried out. Antioxidant administrations before tumor inoculation effectively inhibited its growth in the three experimental protocols, but administrations after the tumor's appearance accelerated tumor growth and favored metastases. Continuous administration of pequi oil inhibited the tumor's growth, while the same protocol with vitamins E and C accelerated it, favoring metastasis and increasing oxidative stress on erythrocytes. Except for continuous administration with vitamin E, the development of ascites tumor metastases was linked with increased inflammation. Results suggest that the efficiency and applicability of antioxidants in the medical clinic can depend not only on the nature of the antioxidant, the type and stage of cancer being treated and the prevailing oxygen partial pressure in the tissues, but also on the type of antioxidant therapy chosen.