Suppression of mitomycin C-induced micronuclei in mouse bone marrow cells by post-treatment with vanillin

Pharmacology of natural radioprotectors

Radiotherapy is one of the most efficient ways to treat cancer. However, deleterious effects, such as acute and chronic toxicities that reduce the quality of life, may result. Naturally occurring compounds have been shown to be non-toxic over wide dose ranges and are inexpensive and effective. Additionally, pharmacological strategies have been developed that use radioprotectors to inhibit radiation-induced toxicities. Currently available radioprotectors have several limitations, including toxicity. In this review, we present the mechanisms of proven radioprotectors, ranging from free radical scavenging (the best-known mechanism of radioprotection) to molecular-based radioprotection (e.g., upregulating expression of heat shock proteins). Finally, we discuss naturally occurring compounds with radioprotective properties in the context of these mechanisms.

Overview of the Role of Vanillin on Redox Status and Cancer Development

Bioactive natural products play critical roles in modern drug development, especially anticancer agents. It has been widely reported that various pharmacological activities of such compounds are related to their antioxidant properties. Vanillin is a natural substance widely found in many plant species and often used in beverages, foods, cosmetics, and pharmaceutical products. Antioxidant and anticancer potential have been described for this compound. Considering the importance of vanillin in the area of human health and food and pharmaceuticals sectors, in this review, we discuss the role of vanillin on redox status and its potential contribution to the prevention and the treatment of cancer.

Use of in vitro assays to assess the potential cytotoxic, genotoxic and antigenotoxic effects of vanillic and cinnamic acid

Vanillic acid (VA) found in vanilla and cinnamic acid (CA) the precursor of flavonoids and found in cinnamon oil, are natural plant phenolic acids which are secondary aromatic plant products suggested to possess many physiological and pharmacological functions. In vitro and in vivo experiments have shown that phenolic acids exhibit powerful effects on biological responses by scavenging free radicals and eliciting antioxidant capacity. In the present study, we investigated the antioxidant capacity of VA and CA by the trolox equivalent antioxidant capacity (TEAC) assay, cytotoxicity by neutral red uptake (NRU) assay in Chinese Hamster Ovary (CHO) cells and also the genotoxic and antigenotoxic effects of these phenolic acids using the cytokinesis-blocked micronucleus (CBMN) and the alkaline comet assays in human peripheral blood lymphocytes. At all tested concentrations, VA (0.17-67.2 μg/ml) showed antioxidant activity but CA (0.15-59.2 μg/ml) did not show antioxidant activity against 2,2-azino-bis (3-ethylbenz-thiazoline-6-sulphonic acid) (ABTS). VA (0.84, 4.2, 8.4, 16.8, 84 and 168 μg/ml) and CA (0.74, 3.7, 7.4, 14.8, 74, 148 μg/ml) did not have cytotoxic and genotoxic effects alone at the studied concentrations as compared with the controls. Both VA and CA seem to decrease DNA damage induced by H₂O₂ in human lymphocytes.

Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde

In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, (1)H and (13)C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data.

Antigenotoxic effects of resveratrol: assessment of in vitro and in vivo response

Experiments were performed to evaluate the in vitro and in vivo dose response for antigenotoxic effects of resveratrol (RES). For the in vitro study, HL-60 cells were co-treated with the test genotoxin and three concentrations of RES. Thereafter, genotoxic effects were assessed in the cytokinesis-block micronucleus test. Results of the in vitro experiments using genotoxins nitroquinoline-1-oxide (NQO) and mitomycin C (MMC) showed maximum inhibition of genotoxicity with the lowest test concentration of RES. The mouse bone marrow micronucleus assay was used for evaluating the in vivo antigenotoxic effects of RES against genotoxins diepoxybutane (DEB), MMC, methyl methanesulfonate and procarbazine (PCB). The experimental animals received RES pre-treatment by gavage 30min, 24 and 48h before injecting the genotoxin intraperitoneally. The in vivo studies demonstrated efficacy of the lowest test dose of RES for exerting maximum protection against chromosomal damage induced by all four genotoxins. The antigenotoxic effect observed with 6.25mg/kg RES was significantly higher than that of 100mg/kg RES against PCB and DEB. In conclusion, the findings from the present study indicate that lower test concentrations/doses of RES are more effective in exerting antigenotoxic effects.

The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

Genotoxic and anti-genotoxic effects of vanillic acid against mitomycin C-induced genomic damage in human lymphocytes in vitro

Vanillic acid, a vegetable phenolic compound, is a strong antioxidant. The aim of the present study was to determine its effects on mitomycin C-induced DNA damage in human blood lymphocyte cultures in vitro, both alone and in combination with mitomycin C (MMC). The cytokinesis block micronucleus test and alkaline comet assay were used to determine genotoxic damage and anti-genotoxic effects of vanillic acid at the DNA and chromosome levels. MMC induced genotoxicity at a dose of 0.25 μg/ml. Vanillic acid (1 μg/ml) significantly reduced both the rates of DNA damaged cells and the frequency of micronucleated cells. A high dose of vanillic acid (2 μg/ml) itself had genotoxic effects on DNA. In addition, both test systems showed similar results when tested with the negative control, consisting of dimethyl sulfoxide (DMSO) in combination with vanillic acid (1 μg/ml) +MMC. In conclusion, vanillic acid could prevent oxidative damage to DNA and chromosomes when used at an appropriately low dose.

Apoptosis and cell cycle arrest of human colorectal cancer cell line HT-29 induced by vanillin

BACKGROUND

Vanillin is responsible for the flavor and smell of vanilla, a widely used flavoring agent. Previous studies showed that vanillin could enhance the repair of mutations and thus function as an anti-mutagen. However, its role in cancer, a disease that is closely related to mutation has not yet been fully elucidated.

METHODS

Hence, this study investigated the cytolytic and cytostatic properties of vanillin against HT-29, a human colorectal cancer cell line. Methods used including cell viability assay, acridine orange (AO)-ethidium bromide (EB) double staining cell morphological analysis, Cell cycle analysis, annexin V-propidium iodide apoptosis test and 5-bromo-2-deoxyuridine (BrdU)-labeling cell proliferation assay.

RESULTS

Results showed that apoptosis was induced by vanillin and the IC(50) for HT-29 and NIH/3T3 normal cell lines were 400 microg/ml and 1000 microg/ml, respectively. Different concentrations of vanillin arrest cell cycle at different checkpoints. 5-Bromo-2-deoxyuridine-labeling cell proliferation assay showed that G0/G1 arrest was achieved at lower concentration of vanillin (200 microg/ml) while cell cycle analysis by flow cytometer showed that G2/M arrest occurs at higher concentration of vanillin (1000 microg/ml).

CONCLUSION

Cytolytic and cytostatic effects shown by vanillin showed that it could be a useful colorectal cancer preventive agent. Further in vivo study should be carried out to confirm that similar effects could happen in animals.

DNA protective properties of vanillin against γ-radiation under different conditions: Possible mechanisms

Ionizing radiation is an important genotoxic agent. Protecting against this form of toxicant, especially by a dietary component, has several potential applications. In the present study, we have examined the ability of vanillin (4-hydroxy-3-methoxybenzaldehyde), a naturally occurring food flavouring agent, to inhibit radiation-induced DNA damage measured as strand breaks under in vitro, ex vivo and in vivo conditions besides the possible mechanisms behind the observed protection. Our study showed that there was a concentration-dependent inhibition of the disappearance of super-coiled (ccc) form of plasmid pBR322 (in vitro) upon exposure to 50 Gy of gamma-radiation. Presence of 0.5 mM vanillin has a dose-modifying factor (DMF) of 6.75 for 50% inactivation of ccc form. Exposure of human peripheral blood leucocytes (ex vivo) to gamma-radiation causes strand breaks in the cellular DNA, as assessed by comet assay. When leucocytes were exposed to 2 Gy of gamma-radiation there was an increase in parameters of comet assay such as %DNA in tail, tail length, 'tail moment' and 'Olive tail moment'. The presence of 0.5 mM vanillin during irradiation significantly reduced these parameters. Damage to DNA in mouse peripheral blood leucocytes after whole-body exposure of mice (in vivo) to gamma-radiation was studied at 1 and 2 h post-irradiation. There was recovery of DNA damage in terms of the above-mentioned parameters at 2 h post-irradiation. This was more than that observed at 1 h. The recovery was more in vanillin treated mice. Hence our studies showed that vanillin offers protection to DNA against radiation-induced damage possibly imparting a role other than modulation of DNA repair. To examine the possible mechanisms of radioprotection, in terms of radiation-derived radicals, we carried out the reaction of vanillin with ABTS*(+) radical spectrophotometrically besides with DNA peroxyl and carbonyl radicals by using pulse radiolysis. Our present investigations show that vanillin has ability to protect against DNA damage in plasmid pBR322, human and mouse peripheral blood leucocytes and splenic lymphocytes besides enhancing survival in splenic lymphocytes against gamma-radiation, and that the possible mechanism may involve scavenging of radicals generated during radiation, apart from modulation of DNA repair observed earlier.

Suppressive effect of post- or pre-treatment of aspirin metabolite on mitomycin C-induced genotoxicity using the somatic mutation and recombination test in Drosophila melanogaster

In our previous paper, we found that aspirin suppressed in a somatic mutation and recombination test (SMART) of mitomycin C (MMC) in Drosophila melanogaster. In order to reveal the mechanism of bio-antimutagenicity and/or preventive effect of aspirin, we evaluated the suppressive ability of each aspirin metabolite, such as salicylic acid (SA), salicyluric acid (SUA), gentisic acid (GA), gentisuric acid (GUA) and 2,3-dihydroxybenzoic acid (DHBA), in SMART in D. melanogaster using post- and pre-treatments. As for the post-treatment, SA reduced the numbers of large single and twin spots. GA reduced the small single and large single spots, and GUA reduced the single spots, large single and twin spots. The inhibition of GUA is slightly stronger than that of any other metabolites; the inhibition percentage is 49 at the dose of 5 mg/bottle. On the other hand, as for the pre-treatment, aspirin, SUA, GA and DHBA reduced the numbers of small single spots. SUA, GE and DHBA reduced the number of large single spots. Aspirin and its metabolites did not reduce the number of twin spots. The results of the present study suggest that SA, GA and GUA repair or replicate DNA-damage by MMC and SUA, GA, GUA and DHBA prevent DNA-damage by MMC. It is suggested that secondary cancer is prevented by aspirin post-treatment without losing the medicinal effectiveness (anti-tumor activity). Therefore, we consider there are effective doses and/or administration timing of aspirin and MMC to prevent secondary cancer.

Antimutagenicity of cinnamaldehyde and vanillin in human cells: Global gene expression and possible role of DNA damage and repair

Vanillin (VAN) and cinnamaldehyde (CIN) are dietary flavorings that exhibit antimutagenic activity against mutagen-induced and spontaneous mutations in bacteria. Although these compounds were antimutagenic against chromosomal mutations in mammalian cells, they have not been studied for antimutagenesis against spontaneous gene mutations in mammalian cells. Thus, we initiated studies with VAN and CIN in human mismatch repair-deficient (hMLH1(-)) HCT116 colon cancer cells, which exhibit high spontaneous mutation rates (mutations/cell/generation) at the HPRT locus, permitting analysis of antimutagenic effects of agents against spontaneous mutation. Long-term (1-3 weeks) treatment of HCT116 cells with VAN at minimally toxic concentrations (0.5-2.5mM) reduced the spontaneous HPRT mutant fraction (MF, mutants/10(6) survivors) in a concentration-related manner by 19-73%. A similar treatment with CIN at 2.5-7.5microM yielded a 13-56% reduction of the spontaneous MF. Short-term (4-h) treatments also reduced the spontaneous MF by 64% (VAN) and 31% (CIN). To investigate the mechanisms of antimutagenesis, we evaluated the ability of VAN and CIN to induce DNA damage (comet assay) and to alter global gene expression (Affymetrix GeneChip) after 4-h treatments. Both VAN and CIN induced DNA damage in both mismatch repair-proficient (HCT116+chr3) and deficient (HCT116) cells at concentrations that were antimutagenic in HCT116 cells. There were 64 genes whose expression was changed similarly by both VAN and CIN; these included genes related to DNA damage, stress responses, oxidative damage, apoptosis, and cell growth. RT-PCR results paralleled the Affymetrix results for four selected genes (HMOX1, DDIT4, GCLM, and CLK4). Our results show for the first time that VAN and CIN are antimutagenic against spontaneous mutations in mammalian (human) cells. These and other data lead us to propose that VAN and CIN may induce DNA damage that elicits recombinational DNA repair, which reduces spontaneous mutations.

The FEMA GRAS assessment of hydroxy- and alkoxy-substituted benzyl derivatives used as flavor ingredients

This publication is the ninth in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). In 1993, the Panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavoring substances under conditions of intended use. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of hydroxy- and alkoxy-substituted benzyl derivatives as flavoring ingredients is evaluated. The group of hydroxy- and alkoxy-benzyl derivatives was reaffirmed as GRAS (GRASr) based, in part, on their self-limiting properties as flavoring substances in food; their rapid absorption, metabolic detoxication, and excretion in humans and other animals; their low level of flavor use; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic and chronic studies and the lack of significant genotoxic and mutagenic potential. This evidence of safety is supported by the fact that the intake of hydroxy- and alkoxy-substituted benzyl derivatives as natural components of traditional foods is greater than their intake as intentionally added flavoring substances.

The synergistic effects of vanillin on recombination predominate over its antimutagenic action in relation to MMC-induced lesions in somatic cells of Drosophila melanogaster

The wing Somatic Mutation And Recombination Test (SMART) in Drosophila melanogaster was used to study the modulating action of vanillin (VA) in combination with the alkylating agents mitomycin C (MMC), methylmethanesulphonate (MMS) and the bifunctional nitrogen mustard (HN2). Two types of treatments with VA and each of the three genotoxins were performed: chronic co-treatments of three-day-old larvae of the standard cross as well as post-treatments after acute exposure with the genotoxins. This allowed the study of the action of VA not only in the steps that precede the induction of DNA lesions but also in the repair processes. The overall findings from the co-treatment series suggest that ingestion of VA with MMS or MMC can lead to significant protection against genotoxicity; but this is not the case with HN2. Antioxidant activity, suppression of metabolic activation or interaction with the active groups of these two alkylating agents could be mechanisms by means of which VA exerts its desmutagenic action. In contrast, when evaluated in the post-treatment procedure, VA causes two antagonistic effects on the genotoxicity of MMC: (i) synergism on recombination (172.8%) and (ii) protection against mutation (79.0%). Consequently, both activities together lead to a considerable increase in mitotic recombination. In spite of being separate events, recombination and gene mutation are correlated during mitosis since the fate of a DNA lesion depends on the repair pathway followed. Our results may suggest that VA is a modifying factor that blocks the mutagenic pathway and consequently directs the MMC-induced lesions into a recombinational repair. Furthermore, VA did not modify the genotoxicity when administered after treatments with HN2 or MMS. Therefore, the major finding of the present study, namely the co-recombinagenic activity of VA on MMC-induced lesions, seems to be related to the type of induced lesion and consequently to the repair processes involved in its correction.

Inhibition of genotoxic effects of mammalian germ cell mutagens

Germ cell mutagens are among the most important chemicals for which chemopreventive agents should be sought and mechanistically defined. These mutagens may include environmental chemicals as well as drugs. In this investigation, the literature was reviewed for substances antimutagenic (or anticlastogenic) to compounds identified as mutagens in at least two germ cell studies. A complete matrix of test results was prepared to identify commonly tested pairs of germ cell mutagens and antimutagens. The categories of antimutagens most tested included vitamins, fatty acids, thiols, tannins and other phenolics. The most frequently studied mutagens were benzo[a]pyrene, cyclophosphamide, mitomycin C, and bleomycin. Based on the availability of the most relevant data, the analysis presented here focused on in vivo tests, specifically on bone marrow cytogenetics. The results indicated that antimutagens commonly found in the diet or endogenously in the body effectively antagonized the cytogenetic damage induced in the bone marrow by most of the germ cell mutagens studied to date. Bone marrow micronucleus and chromosomal aberration assays, which detect systemically active mutagens, may be predictive of similar mitigating effects in germ cells. Test results from antimutagenicity studies in germ cells, though limited, were comparable to the results from studies in the mouse bone marrow micronucleus test.

Protective effect of vanillin on radiation-induced micronuclei and chromosomal aberrations in V79 cells

Vanillin (VA), an anticlastogen, has been demonstrated to inhibit gene mutations in both bacterial and mammalian cells. However, the data on its effect against radiation-induced cytogenetic damage are limited. The aim of this study was to investigate the protective effect of VA on radiation-induced chromosomal damage in V79 cells. Exponentially growing cells were exposed to five doses of X-rays (1-12 Gy) and UV radiation (50-800 microJ x 10(2) cm-2 and posttreated with 3 concentrations of VA (5, 50 or 100 micrograms ml-1 for 16 h for micronucleus (MN) and 18 h for structural chromosomal aberration (SCA) analyses. MN and SCA assays were performed concurrently according to standard procedures. Results indicate that there was a dose related increase in the percent of micronucleated binucleated cells (MNBN) (5.6 to 79.6) and percent of aberrant cells (Abs) (12 to 98) with X-ray treatment alone. Inhibition studies showed that the addition of VA at 100 micrograms ml-1 significantly reduced the percent of MNBN (21 to 48) induced by X-ray at 1, 2, and 4 Gy. There was a slight decrease in percent MNBN at 5 and 50 micrograms VA ml-1. All three concentrations of VA decreased percent Abs (15.7 to 57.1) induced by X-rays at all doses. UV radiation alone significantly increased percent MNBN (3.5 to 14.8) and percent Abs (17 to 29). Addition of 50 or 100 micrograms VA ml-1, significantly decreased percent MNBN (31.7 to 86.2) and percent Abs (54.5 to 90.9) at all doses of UV radiation. A decrease in percent MNBN (2.8 to 72.4) and percent Abs (34.8 to 66.7) was also noted at 5 micrograms VA ml-1. These data clearly indicate the protective effect of VA on radiation-induced chromosomal damage, suggesting that VA is an anticlastogenic agent.

Suppressing effects of S-methyl methanethiosulfonate and diphenyl disulfide on mitomycin C-induced somatic mutation and recombination in Drosophila melanogaster and micronuclei in mice

S-Methyl methanethiosulfonate (MMTS) and diphenyl disulfide (DPDS) are temporary enzyme-sulfhydryl blocking agents. They are naturally occurring phytoalexin-like and synthetic substances known to be very potent bio-antimutagens in Escherichia coli B/r WP2. In the present paper, the suppressing effects of MMTS on mitomycin C (MMC)-induced mutant wing spots in the somatic mutation and recombination test (SMART) of Drosophila melanogaster, and of MMTS and DPDS on MMC-induced micronucleated peripheral reticulocytes are described. MMTS consistently reduced the numbers of MMC-induced small single, large single and twin spots per wing at a dose of 10-1000 micrograms/vial, in a dose-dependent manner. MMTS reduced the number of twin spots per wing on the spontaneous mutation at the dose of 1000 micrograms/vial. MMTS and DPDS dose-dependently reduced the frequencies of MMC-induced micronucleated peripheral reticulocytes at a dose of 10-40, and 3-100 micrograms/kg, respectively. Our results confirmed that enzyme-sulfhydryl blocking agents, such as MMTS and DPDS, are effective antimutagens in vivo too.

Modulation of toxicity by dietary and environmental factors

Both epidemiological and experimental evidence indicate that environmental factors may modulate chemical toxicity. Of these, dietary factors have been most thoroughly studied and shown to modulate a number of toxic processes including carcinogenesis. Total energy intake and specific nutrients (protein and specific amino acids, vitamins, and minerals) have been shown to be active in this regard as have a number of non-nutritive dietary factors, most notably phenolic and sulphur-containing compounds, and indoles. The mechanisms by which dietary factors might influence toxicity include effects on bioavailability, phase I or phase II metabolism, scavenging of reactive metabolites, induction of DNA repair processes, inhibition of cell proliferation, induction of differentiation or apoptosis and effects on the immune system. These factors are discussed with emphasis on dietary exposure to modulating factors.

Genotoxic effects produced by capsaicin in mouse during subchronic treatment

Capsaicin is the chemical responsible for the pungent, hot properties of Capsicum, a vegetable widely consumed in the diet of many countries in the world. In this work, the genotoxic capacity of capsaicin was studied in mouse during a 32-day treatment. We used the dosages of 1.46 and 1.94 mg/kg given by the i.p. route. Each week, the frequency of micronucleated normochromatic erythrocytes (MN-NE) and the ratio polychromatic/normochromatic erythrocytes (PE/NE) were scored. At the end of the experiment we also scored the frequency of sister chromatid exchanges (SCE). The results in the MN-NE analysis showed a genotoxic response with 1.94 mg/kg starting from day 16, while the 1.46 mg/kg dose produced a significant increase of MN-NE only at the 32nd day. The ratio PE/NE was only affected at the 32nd day with the high dose. Concerning the SCE frequency, the genotoxic effect was only observed with the highest dose. These results indicated that capsaicin is a genotoxicant, and due to the probable relation between an excessive consumption of Capsacum and an increase in gastric cancer, it is suggested that its consumption could be moderated until a definitive risk for humans is established.

Effects of cinnamaldehyde on survival and formation of HGPRT- mutants in V79 cells treated with methyl methanesulfonate, N-nitroso-N-methylurea, ethyl methanesulfonate and UV light

The effects of the antimutagenic flavoring cinnamaldehyde on the induction of HGPRT- mutants by methyl methanesulfonate (MMS), N-nitroso-N-methylurea (MNU), ethyl methanesulfonate (EMS) and UV light was investigated in the Chinese hamster V79 cell line. Cinnamaldehyde did not show any mutagenic or toxic effects in this experimental system by itself and did not modify mutation frequency when given to cells simultaneously with chemical mutagens. Under these conditions, the cytotoxicity of MMS, but not that of MNU and EMS, was increased. Cell viability was also reduced in MNU-, EMS-, or UV light-pretreated cells when they were postincubated in the presence of cinnamaldehyde. Moreover, cinnamaldehyde reduced the frequency of mutations induced by MMS but not by the other mutagens. The results obtained suggest that cinnamaldehyde inhibits some cellular function(s) promoting the repair of a variety of different cytotoxic lesions. At the same time, stimulation by cinnamaldehyde of an error-free DNA repair mechanism acting on MMS-induced mutagenic damage was indicated.

Bio-anticlastogenic effects of unsaturated fatty acids included in fish oil--docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid--in cultured Chinese hamster cells

Bio-anticlastogenic effects of unsaturated fatty acids--cis-4,7,10,13,16,19-docosahexaenoic acid (DHA), cis-7,10,13,16,19-docosapentaenoic acid (DPA), and cis-5,8,11,14,17-eicosapentaenoic acid (EPA)--on chemically induced chromosome aberrations were studied in cultured Chinese hamster cells. The induction of chromosome aberrations by the crosslinking agents mitomycin C (MMC) and cisplatin (DDP), the SN-1 type alkylating agents N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG), methyl nitrosourea (MNU), and ethyl nitrosourea (ENU), and the SN-2 type alkylating agent ethyl methanesulfonate (EMS), but not by the SN-1 type alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and the SN-2 type alkylating agent methyl methanesulfonate (MMS), was suppressed by post-treatment with DHA, DPA, and EPA. Since there was no opportunity to inactivate mutagens by desmutagenic mechanisms under the post-treatment schedule used, the results demonstrate the bio-anticlastogenicity of unsaturated fatty acids. Suppression by the unsaturated fatty acids was observed when cells were treated during the G2 phase, suggesting that G2 events were responsible for the bio-anticlastogenic effects. Two saturated fatty acids with the same number of carbons as the studied unsaturated fatty acids--docosanoic acid and eicosanoic acid--did not affect chromosome aberration induction, suggesting the necessity of unsaturation for fatty acid bio-anticlastogenicity.

Bone marrow micronucleus assay: a review of the mouse stocks used and their published mean spontaneous micronucleus frequencies

We have examined published negative control data from 581 papers on micronucleated bone marrow polychromatic erythrocytes (mnPCE) for differences in mean frequency and the frequency distribution profile among the mouse stocks used with the bone marrow micronucleus assay. For the 55 mouse stocks with published micronucleus assay data, the overall mean frequency is 1.95 mnPCE/1,000 PCE (1.95 mnPCE/1,000); for the 13 stocks most commonly used in the assay, it is 1.88 mnPCE/1,000. During the last 5 years, the mnPCE rate for these 13 major stocks has been 1.74 mnPCE/1,000. This current mean frequency is a substantial decrease from the mean of 3.07 mnPCE/1,000 observed for these 13 stocks for data published prior to 1981. Of the major stocks, the highest mean mnPCE negative control frequencies were observed for MS/Ae > BALB/c > C57Bl/6, and the lowest for CD-1 < Swiss Webster. We note that hybrid mouse stocks appear to have lower and less variable negative control frequencies than either of their parent strains and that the negative control frequency for some progeny stocks have diverged significantly from that of the parent stocks. Overall mean negative control frequencies appear to be correlated with breadth of the frequency distribution profile of published mean negative control values. Furthermore, a possible correlation between negative control frequency in the micronucleus assay and sensitivity to clastogens of different mouse strains may be indicated. The databases generated here allow us to define a range of norms for both the historical mean frequency and individual experimental mean frequencies for most stocks, but in particular, for the more commonly used mouse stocks. Our analysis, for the most part, bears out the recommendation of the first Gene-Tox Report on the micronucleus assay that the historical negative control frequency for a mouse stock should fall between 1 and 3 mnPCE/1,000. Eighty-six percent of the most commonly used mouse stocks have historical mean frequencies within this range. Though individual experimental mean values would not necessarily be expected to fall within the 1-3.00 mnPCE/1,000 range, 65.3% of the 2,327 published negative control values do, and 83.5% are < 3 mnPCE/1,000. The frequency with which an individual experimental mean value lies outside the 1.00 to 3.00 mnPCE/1,000 range differs among stocks and appears related to the mouse mean frequency. We suggest that the recommended range for historical mean frequency be extended slightly, to approximately 3.4 mnPCE/1,000, to accommodate some commonly used strains with overall mean negative control frequencies just above 3.00 mnPCE/1,000.(ABSTRACT TRUNCATED AT 400 WORDS)

Inorganic cadmium increases the frequency of chemically induced chromosome aberrations in cultured mammalian cells

The co-clastogenic effect of cadmium ion (Cd2+) was studied in Chinese hamster CHO K1 cells and excision repair-deficient human XP20SSV cells. Cd2+ at < or = 28.0 microM did not show any clastogenic effects under the experimental conditions used. Cd2+ post-treatment at < or = 3.50 microM, however, increased the number of both breakage- and exchange-type chromatid aberrations induced by mitomycin C (MMC) and 4-nitroquinoline 1-oxide (4NQO) in CHO K1 cells. Enhancement of chromosome aberrations induced by MMC was observed when CHO K1 cells were treated with Cd2+ during the G1 phase. Cd2+ was also co-clastogenic with MMC in XP20SSV cells. Its co-clastogenic effect, however, was not observed in 4NQO-treated XP20SSV cells. These results suggest that Cd2+ inhibits DNA pre-replicational repair, perhaps DNA excision repair, thereby causing co-clastogenic effects.

o-Vanillin enhances chromosome aberrations induced by alkylating agents in cultured Chinese hamster cells

The enhancing effects of o-vanillin (2-hydroxy-3-methoxybenzaldehyde) on structural chromosome aberrations induced by alkylating agents were studied in cultured Chinese hamster cells. o-Vanillin was not a clastogen by itself. When cells were treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the presence of 400 micrograms/ml of o-vanillin for 2 h, the frequency of aberrant cells with chromosome aberrations was increased 2.8-fold compared with cells treated with MNNG alone. The total number of breakage-type and exchange-type aberrations was increased 18.5- and 8.3-fold, respectively. The enhancing effects were also observed for chromosome aberrations induced by N-methyl-N-nitrosourea and N-ethyl-N-nitrosourea. On the other hand, those induced by N-butyl-N-nitrosourea were only slightly enhanced. The frequency of chromosome aberrations induced by mitomycin C or bleomycin was not changed by o-vanillin treatment. It was considered that DNA repair of methylated damage may be inhibited by o-vanillin.

Modification of genotoxicity by naturally occurring flavorings and their derivatives

The number of studies in the research field of antimutagenesis is increasing. The aims of many of these studies are preventing genetic hazards from environmental mutagens and elucidating the process of mutagenesis. Some naturally occurring flavorings such as vanillin, cinnamaldehyde, and coumarin have been reported to inhibit mutagenesis induced by mutagens in bacterial and mammalian cells. These flavorings are considered to act as antimutagens by modifying DNA replication and/or DNA repair systems after cellular DNA was damaged by mutagens. A factor that suppresses mutagenicity in a given situation, however, sometimes exerts enhancing effects when the endpoints investigated or the test conditions used are varied. This makes the evaluation of antimutagenic factors complicated. Different modifying effects of the above-mentioned flavorings observed in various test systems for genotoxicity are discussed, based on their proposed mechanisms.

Enhancing effects of heterocyclic amines and beta-carbolines on the induction of chromosome aberrations in cultured mammalian cells

The effects of post-treatment with heterocyclic amines and beta-carbolines on the induction of chromosome aberrations were studied in Chinese hamster CHO K-1 cells and SV40-transformed excision repair-deficient human XP2OSSV cells. The number of chromosome aberrations induced by UV and MMC were increased by post-treatment with Trp-P-1 and Trp-P-2, in both the presence and the absence of S9 mix. A alpha C, MeA alpha C, Glu-P-1, Glu-P-2, IQ, MeIQ, harman and harmine increased chromosome aberrations only in the presence of S9 mix. Glu-P-2, IQ, MeIQ, harman, and harmine did not induce chromosome aberrations by themselves at the concentrations used in this study. Trp-P-1, Trp-P-2, A alpha C, MeA alpha C and Glu-P-1 were weak clastogens by themselves, but at much higher concentrations than those at which they increased the induction of chromosome aberrations in cells pretreated with UV or MMC. Therefore, the increases in chromosome aberrations were not considered to be additive.

Different modifications by vanillin in cytotoxicity and genetic changes induced by EMS and H2O2 in cultured Chinese hamster cells

The modifying effects of vanillin on the cytotoxicity and 6-thioguanine (6TG)-resistant mutations induced by two different types of chemical mutagens, ethyl methanesulfonate (EMS) and hydrogen peroxide (H2O2), were examined using cultured Chinese hamster V79 cells. The effects of vanillin on H2O2-induced chromosome aberrations were also examined. Vanillin had a dose-dependent enhancing effect on EMS-induced cytotoxicity and 6TG-resistant mutations, when cells were simultaneously treated with vanillin. The post-treatment with vanillin during the mutation expression time of cells after treatment with EMS also showed an enhancement of the frequency of mutations induced by EMS. However, vanillin suppressed the cytotoxicity induced by H2O2 when cells were post-treated with vanillin after H2O2 treatment. Vanillin showed no change in the absence of activity of H2O2 to induce mutations. Post-treatment with vanillin also suppressed the chromosome aberrations induced by H2O2. The differential effects of vanillin were probably due to the quality of mutagen-induced DNA lesions and vanillin might influence at least two different kinds of cellular repair functions. The mechanisms by which vanillin enhances or suppresses chemical-induced cytotoxicity, mutations and chromosome aberrations are discussed.

Suppressing effect of vanillin on chromosome aberrations that occur spontaneously or are induced by mitomycin C in the germ cell line of Drosophila melanogaster

In order to investigate the anticlastogenic effect of vanillin on ring-X loss, D. melanogaster females exposed to different vanillin concentrations were crossed with non-treated, MMC- or MMS-treated males. The results obtained with this in vivo investigation showed a significant inhibition of vanillin in the frequencies of spontaneous ring-X loss--59, 56, 38 and 36%--at the different concentrations used. In addition, vanillin treatment caused a significant suppression of MMC-induced ring-X loss. This decrease was observed only in the first 3 days after the interruption of vanillin treatment and at the concentrations of 0.5 and 1% of this flavoring agent. In contrast, vanillin did not show any effect on chromosome loss provoked by MMS. Therefore, the ring-X loss-decreasing effect of vanillin seemed to depend on the quality of DNA lesions and consequently on a specific enzymatic repair process present in the oocytes of D. melanogaster.

Bio-antimutagenic activities of vitamin B6 in E. coli and mouse peripheral blood cells

Pyridoxal (PL) and pyridoxal 5'-phosphate (PLP) showed a marked bio-antimutagenic effect on UV-induced mutagenesis in E. coli B/r WP2, but not in the DNA excision repair-deficient strain WP2suvrA under the condition where no cellular toxicity was observed. No delay in the first cell division was seen on post-treatment with PL after UV irradiation. PL reduced not only UV- but 4-nitroquinoline-1-oxide-induced mutation, while it was ineffective in N-methyl-N'-nitro-N-nitrosoguanidine- or gamma-ray-treated cells. These results suggest that PL promotes DNA excision repair directly or indirectly and the decrease in the amount of unrepaired DNA damage might cause the reduction of UV-induced mutations in E. coli B/r WP2. In addition to the above observation, PLP reduced the frequency of mitomycin C- (2 mg/kg, i.p.) induced micronuclei in mouse peripheral blood cells. Simultaneous or subsequent oral administration of PLP (25 mg/kg) decreased the frequency of micronucleated peripheral reticulocytes.

Modulation of cyclophosphamide mutagenicity by vitamin C in the in vivo rodent micronucleus assay

The modulatory effect of vitamin C (Vit C) on the mutagenic effect of the antineoplastic drug cyclophosphamide (CP) was assessed in the in vivo micronucleus test in Swiss mice. Simultaneous oral administration of Vit C with i.p. administration of CP was found to decrease the frequency of micronucleated polychromatic erythrocytes elevated by CP. Vit C exhibited a significant antimutagenic effect over a wide dose range (1.56-200 mg/kg). The dose-response relationship was highly significant. These results demonstrated the ability of the in vivo micronucleus test to detect in vivo modulation of CP mutagenicity by Vit C. Our earlier results and those from other laboratories also indicate that this model system is suitable for primary in vivo screening of modulation of mutagenesis.

Kinetochore analysis of micronuclei allows insights into the actions of colcemid and mitomycin C

We have induced micronuclei in two strains of diploid human fibroblasts with a known aneugen, colcemid, and a known clastogen, mitomycin C. Using immunofluorescence to detect the presence of kinetochores in micronuclei, we were able to demonstrate a 26.8-fold increase in fluorescence-positive micronuclei (aneuploidy) in colcemid-treated cells. However, colcemid also induced an increase in kinetochore-negative micronuclei. Our findings support previous reports that suggest colcemid may induce chromosome breakage in addition to its major aneugenic effect. The frequency of kinetochore-negative micronuclei (chromosome breakage) in mitomycin C-treated cells rose an average of 7.9-fold in the two test strains, a clear reflection of its clastogenic action. However, a 4-fold increase in the kinetochore-positive fraction was seen. We conclude that the fibroblast micronucleus assay, coupled with kinetochore immunofluorescence, provides a useful screening approach for genotoxic agents. The delineation of the precise mechanism by which an agent perturbs the rates of chromosomal breakage or lag may require more detailed analysis.

Suppressing effects of vanillin, cinnamaldehyde, and anisaldehyde on chromosome aberrations induced by X-rays in mice

X-ray-induced chromosome aberrations were suppressed when vanillin, cinnamaldehyde, or p-anisaldehyde was given orally to mice after X-ray irradiation. Chromosome aberrations were monitored by the occurrence of polychromatic erythrocytes with micronuclei in bone marrow cells. The frequency of micronuclei was depressed about 55-60% without toxicity of the test compounds to the bone marrow.

Suppressing effect of antimutagenic flavorings on chromosome aberrations induced by UV-light or X-rays in cultured Chinese hamster cells

Chromosome aberrations induced by UV-light or X-rays were suppressed by the post-treatment with antimutagenic flavorings, such as anisaldehyde, cinnamaldehyde, coumarin, and vanillin. UV- or X-ray-irradiated surviving cells increased in the presence of each flavoring. X-ray-induced breakage-type and exchange-type chromosome aberrations were suppressed by the vanillin treatment in the G1 phase of the cell cycle and a greater decrease in the number of X-ray-induced chromosome aberrations during G1 holding was observed in the presence of vanillin. Furthermore, a greater decrease in the number of X-ray-induced DNA single-strand breaks was observed in the presence of vanillin. Treatment with vanillin in the G2 phase suppressed UV- and X-ray-induced breakage-type but not exchange-type chromosome aberrations. The suppression of breakage-type aberrations was assumed to be due to a modification of the capability of the post-replicational repair of DNA double-strand breaks. These G1- and G2-dependent anticlastogenic effects were not observed in the presence of 2',3'-dideoxythymidine, an inhibitor of DNA polymerase beta. Based on these results, the anticlastogenic effect of vanillin was considered to be due to the promotion of the DNA rejoining process in which DNA polymerase beta acts.

Suppression of 6-TG-resistant mutations in V79 cells and recessive spot formations in mice by vanillin

The antimutagenic effects of vanillin, anisaldehyde, cinnamaldehyde and coumarin were investigated in cultured Chinese hamster V79 cells in vitro. The frequencies of 6-TG-resistant mutations induced by UV or X-rays were decreased by treatment with each compound during the expression time. These decreases were not due to cytotoxic effects on cellular growth or killing effects on damaged cells. The antimutagenic effect of vanillin was also investigated in vivo in the mouse spot test using male PW and female C57BL/10 mice. Female mice were injected intraperitoneally with ethylnitrosourea (ENU) on the 10th day of pregnancy and received 3 successive oral administrations of vanillin. Administration of vanillin decreased the ENU-induced frequency of recessive carrier pups. These results indicate that vanillin acts as an antimutagen in mammalian cells both in vitro and in vivo.

Enhancement and inhibition of mutation by o-vanillin in Escherichia coli

2-Hydroxy-3-methoxybenzaldehyde (omicron-vanillin), the antimutagenic effect of which has been reported on mutagenesis induced by 4-nitroquinoline 1-oxide (4NQO) in Escherichia coli WP2s, enhanced N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutagenesis in the same strain. A remarkable enhancement of mutagenesis provoked by N-methyl-N-nitrosourea (MNU) was also observed by the addition of omicron-vanillin. No enhancing effect was observed on mutagenesis induced by other mutagens such as methyl methanesulfonate (MMS), dimethylsulfate, N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG), N-ethyl-N-nitrosourea (ENU), ethyl methanesulfonate, diethylsulfate, 4NQO and furylfuramide (AF-2). On the contrary, omicron-vanillin greatly suppressed AF-2- and 4NQO-induced mutagenesis and showed a slight suppressing effect against mutagenesis induced by MMS, ENNG and ENU. One possible explanation for the enhancing effect of omicron-vanillin on the mutagenesis induced by MNNG or MNU in E. coli WP2s may be inhibition of an inducible adaptive response. Among 7 derivatives of omicron-vanillin, 2-hydroxy-3-ethoxy-benzaldehyde, omicron-hydroxybenzaldehyde and m-methoxybenzaldehyde showed an enhancing effect on MNNG-induced mutagenesis.

Suppressing effect of tannic acid on the frequencies of mutagen-induced sister-chromatid exchanges in mammalian cells

The effects of tannic acid (m-galloyl gallic acid) and 7 of its analogues on the frequencies of sister-chromatid exchanges (SCEs) were investigated in cultured Chinese hamster cells. SCEs induced by UV-light or mitomycin C (MMC) were suppressed by post-treatment with tannic acid and 5 of its analogues. These effects were independent of the extension of the cell cycle. The compounds which showed an SCE-suppressing effect have a common structure of 3 neighboring hydroxy or methoxy groups substituted on the phenyl group in benzoic acid or ester. These decreasing effects of tannic acid were observed in the G1 phase but not in the S or G2 phase of the cell cycle and a greater decline of the frequencies of UV-induced SCEs during liquid holding was seen in the presence of tannic acid. However, cells irradiated with X-rays were not influenced by tannic acid. In cells from a xeroderma pigmentosum (XP) patient, a Fanconi's anemia (FA) patient, and a normal human embryo, MMC-induced SCEs were also decreased by post-treatment with tannic acid. Tannic acid reduced the SCE frequencies in UV-irradiated FA and normal human cells but not in UV-irradiated XP cells. Our results suggest that tannic acid modifies DNA-excision repair and that the decrease in the amount of unrepaired DNA damage might cause the reduction of induced SCEs.