Analysis of Photomutagenicity of Thiabendazole with UVA Irradiation: Absence of 8-Hydroxyguanosine Formation

Watanabe-Akanuma, Mie; Inaba, Yohei; Ohta, Toshihiro

doi:10.3123/jemsge.28.103

Cited by 3 publications

(5 citation statements)

References 16 publications

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“…S. typhimurium strains TA1978P (hisD3052, rfa/pKM101) and TA98 (hisD3052, uvrB, rfa/pKM101) were used for the reverse mutation assays. TA1978P was constructed by conjugation between TA1978 (10) and Escherichia coli WP2uvrA/pKM101 (11,12). TA1978 and TA98 were obtained from Prof. Bruce N. Ames (CA, USA).…”

Section: Introductionmentioning

confidence: 99%

Mutagenic Activity of a Mixture of Heterocyclic Amines at Doses below the Biological Threshold Level of Each

Ohta

2006

Genes and Environment

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The combined mutagenic eŠects of six heterocyclic amines (Trp-P-1, Trp-P-2, Glu-P-1, Glu-P-2, MeIQ, and IQ) at doses below the biological threshold level of each were investigated in the reverse mutation assay with Salmonella typhimurium. The lowest mutagenic doses of heterocyclic amines in TA1978P (hisD3052, rfa/pKM101) were 40 to 200 times the lowest mutagenic doses in TA98 (hisD3052, rfa, uvrB/pKM101), a strain deˆcient in nucleotide excision repair. The six heterocyclic amines were mixed at doses below the biological threshold that were mutagenic to TA98 but not to TA1978P. A signiˆcant increase in the number of revertants in TA1978P was observed with combined heterocyclic amines. The results suggest that DNA adduct formation at doses below the biological threshold level was additive, with the total amount re‰ecting the mutagenicity. We should consider the potential for additive eŠects of mutagens when we consider biological thresholds, because most of environmental mutagens exist in complex mixtures of chemicals.

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Section: Introductionmentioning

confidence: 99%

Mutagenic Activity of a Mixture of Heterocyclic Amines at Doses below the Biological Threshold Level of Each

Ohta

2006

Genes and Environment

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“…We mixed DNA (0.5 mg) and maltol (0.06, 0.13, 0.25, 0.5 and 1.0 mg) into 0.25 ml sodium phosphate buffer in each well of a 24-well multiplate (final concentrations of maltol were 0.25, 0.5, 1, 2 and 4 mg/ml), irradiated the mixture with UVA for 20 min, and then dialysed the reaction mixture against water. N-nitrosopyrrolidine (Sigma-Aldrich) dissolved in sodium phosphate buffer was used as a positive control (12,20). We treated the dialysed DNA with Nuclease P1 (5 unit, Seikagaku, Tokyo) in sodium acetate buffer (20 mM, pH 4.8) at 37 C for 2 h, and then by bacterial alkaline phosphatase (1 unit, Takara Bio Inc., Shiga, Japan) in Tris-HCl buffer (100 mM, pH 8.0) at 37 C for an additional 2 h (20).…”

Section: -Ohdg Assaymentioning

confidence: 99%

“…N-nitrosopyrrolidine (Sigma-Aldrich) dissolved in sodium phosphate buffer was used as a positive control (12,20). We treated the dialysed DNA with Nuclease P1 (5 unit, Seikagaku, Tokyo) in sodium acetate buffer (20 mM, pH 4.8) at 37 C for 2 h, and then by bacterial alkaline phosphatase (1 unit, Takara Bio Inc., Shiga, Japan) in Tris-HCl buffer (100 mM, pH 8.0) at 37 C for an additional 2 h (20). We then removed the enzymes by ultrafiltration (14 000 g, 10 min) with Microcon YM-30 (Millipore, USA), added 1 ml 500 mM EDTA (pH 8.0) to the filtered samples and kept the mixture at À20 C. We measured the amount of deoxyguanosine (dG) and 8-hydroxy-2 0 -deoxyguanosine (8-OHdG) using a high-performance liquid chromatography (HPLC) system (Tosoh, Japan).…”

Section: -Ohdg Assaymentioning

confidence: 99%

Mutagenicity of UV-irradiated maltol in Salmonella typhimurium

2006

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We investigated the photomutagenicity of maltol (3-hydroxy-2-methyl-4H-pyran-4-one) in bacterial cells. Maltol has a caramel-butterscotch odour and is used as a food additive to impart flavour to bread and cakes. Unirradiated maltol was not mutagenic up to 5 mg/plate in the Ames test. When maltol was irradiated with either UVA (a black light, 320-400 nm, 230 microW/cm(2)) for 5-30 min or UVC (a germicidal lamp, 610 microW/cm(2)) for 3 min in sodium phosphate buffer (pH 7.4) prior to the exposure of bacterial cells, it was mutagenic to Salmonella typhimurium TA100, TA104 and TA97. Mutagenic activation of maltol by UVA-irradiation was more evident in neutral and alkaline conditions (pH 7.0-9.0) than in acidic conditions. On the other hand, photomutagenicity was not observed when maltol was irradiated with UVA in 100 mM NaCl solution or water. The mutagenic photoproduct was stable for at least 60 min after UVA-irradiation. However, addition of thiol compounds (cysteine or glutathione) to the UVA-irradiated maltol diminished the mutagenicity. Mutational spectrum analysis revealed that the predominant base-substitutions induced were G:C-->T:A transversions and G:C-->A:T transitions. An increase of 8-hydroxydeoxyguanosine formation in salmon sperm DNA exposed to maltol and UVA in vitro was detected by HPLC-ECD, but it was too small to explain the photomutagenicity. We are considering the formation of DNA adducts as the photomutagenic mechanism.

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“…Last decade we have studied combined genotoxic eŠect of environmental chemicals with UVA-irradiation. We found thiabendazole [2-(4-thiazolyl)-1H-benzimidazole, TBZ], a post-harvest fungicide, showed po- tent mutagenicity, probably by adduct formation, following UVA irradiation in Escherichia coli strain WP2uvrA/pKM101 and Salmonella typhimurium strains TA97 and TA104 (13,14). We recently reported a photomutagenic property of maltol (3-hydroxy-2methyl-4H-pyran-4-one), a food additive used as a ‰avoring.…”

Section: Introductionmentioning

confidence: 99%

“…Photomutagenicity of Cigarette Smoke Condensate alkaline phosphatase were described previously (14). 8-Hydroxy-2?-deoxyguanosine (8-OHdG) was measured using a HPLC system (Shimadzu, Japan) with an electrochemical detector (ECD) and deoxyguanosine (dG) was measured by UV absorption at 254 nm (14). Ratio of 8-OHdG/10 5 dG (nM) in the sample was determined.…”

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confidence: 99%

Photomutagenicity of Sidestream Smoke Condensate of Cigarette with UVA-irradiation

Koshida

Onodera

Arai

et al. 2010

Genes and Environment

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Sidestream smoke from smoldering cigarette is the major source of environmental cigarette smoke. Cigarette smoke condensate (CSC) from sidestream smoke has been known to be mutagenic in Ames' Salmonella strains in the presence of an S9 metabolic activation system. We investigated a novel photomutagenic property of CSC with UVA-irradiation in the absence of metabolic activation. CSCs were collected from sidestream smoke of three Japanese brands of cigarettes using a smoking machine according to the ISO Standard. Bacterial cells with or without CSC were irradiated using a UVA light (320-400 nm) for 10-30 min. Photomutagenicity of CSC was more evident in E. coli WP2uvrA/pKM101 than in S. typhimurium TA100 and TA98. Photomutagenic potency (number of induced revertants/mg CSC) of sidestream CSC from Mild Seven One, an ultra-light tar cigarette, showed equal mutagenic potency to that from Seven Stars, a high tar cigarette. Photomutagenic potency of Pianissimo One, an ultra-light tar cigarette, was signiˆcantly higher than that of Seven Stars or Mild Seven One. We could not detect any increase of 8-OHdG formation in DNA isolated from cells irradiated with UVA in the presence of CSC. CSC with UVA irradiation caused A:T→T:A transversions most frequently, followed by A:T→G:C transitions. CSC was not photomutagenic in WP2/pKM101, indicating that the DNA damages generated by UVA-irradiated CSC were e‹ciently repaired by a nucleotide excision repair system. In addition, an error-prone translesion DNA synthesis by DNA polymerase RI encoded by mucAB genes on pKM101 is considered to be involved in photomutagenesis of CSC. We speculate a possible mechanism of production of radicals followed by DNA bulky adduct formation.

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Analysis of Photomutagenicity of Thiabendazole with UVA Irradiation: Absence of 8-Hydroxyguanosine Formation

Cited by 3 publications

References 16 publications

Mutagenic Activity of a Mixture of Heterocyclic Amines at Doses below the Biological Threshold Level of Each

Mutagenic Activity of a Mixture of Heterocyclic Amines at Doses below the Biological Threshold Level of Each

Mutagenicity of UV-irradiated maltol in Salmonella typhimurium

Photomutagenicity of Sidestream Smoke Condensate of Cigarette with UVA-irradiation

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