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Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Study initiation date - 09 March 1999; Experiment start date - 17 March 1999; Experiment completion date - 06 April 1999; Study completion date - 26 April 1999.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report date:
1999

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Qualifier:
according to guideline
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
Version / remarks:
"Kanpoan No. 287 ~ Environment Protection Agency"
"Eisei No. 127 ~ Ministry of Health & Welfare"
"Heisei 09/10/31 Kikyoku No. 2 ~ Ministry of International Trade & Industry"
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
429-240-8
EC Name:
-
Cas Number:
212652-59-0
Molecular formula:
Hill formula: C25 H22 F N8 Na3 O13 S4 CAS formula: C25 H25 F N8 O13 S4 · 3 Na
IUPAC Name:
trisodium 3-amino-4-[2-(4-{[4-({2-[2-(ethenesulfonyl)ethoxy]ethyl}amino)-6-fluoro-1,3,5-triazin-2-yl]amino}-2-sulfonatophenyl)diazen-1-yl]-5-hydroxynaphthalene-2,7-disulfonate
Specific details on test material used for the study:
Identity: FAT 40574/B
Batch: WP 23/99
Purity: Approx. 75 %
Appearance: Solid, dark-red powder
Storage: At room temperature at about 20 °C
Expiration Date: 08 February 2006

Method

Target gene:
Histidine
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Details on mammalian cell type (if applicable):
Regular checking of the properties of the strains regarding the membrane permeability and ampicillin resistance as well as spontaneous mutation rates is performed in RCC Cytotest Cell Research according to Ames et al. In this way it was ensured that the experimental conditions set down by Ames were fulfilled.
The bacterial strains TA 1535, TA 98, and TA 100 were obtained from Dr. B.N. Ames (University of California, 94720 Berkeley, U.S.A.). The bacterial strain TA 1537 was obtained from BASF (D-67063 Ludwigshafen). The bacterial strain WP2 uvrA was obtained from Dr. Heinz Träger, Knoll AG, D-67008 Ludwigshafen.
Metabolic activation:
with and without
Metabolic activation system:
S9 liver fractions of rats induced with phenobarbital/ ß-naphthoflavone.
The S9 liver microsomal fraction was obtained from the livers of 8 - 12 weeks old male rats, strain Wistar Hanlbm (BRL, CH-4414 Füllinsdorf; weight approx. 220 - 320 g) which received daily applications of 80 mg/kg b.w. Phenobarbital i.p. dissolved in aqua deionised (Desitin; D-22335 Hamburg) and ß-Naphthoflavone orally dissolved in corn oil (Aldrich, D-89555 Steinheim) on three subsequent days. The livers were prepared 24 hours after the last treatment. After decapitation of the anaesthetised animals the livers of the animals were removed, washed in 150 mM KCl and homogenised. The homogenate was diluted 1+3 in KCl and centrifuged cold at 9,000 g for 10 minutes at 4 °C. A stock of the supernatant containing the microsomes was frozen in ampoules and stored at -80° C. Small numbers of the ampoules are kept at - 20 °C for up to one week before use. The protein content was determined using an analysis kit of Bio-Rad Laboratories, D-80939 München (Bio-Rad protein assay, Catalogue No. 5000006). The protein concentration in the S9 preparation was 30 mg/ml (lot no. 280199) in the pre-experiment and in experiment I, and 35.9 mg/ml (lot no. 260299) in experiment II.

S9Mix
Before the experiment an appropriate quantity of S9 supernatant was thawed and mixed with S9 co-factor solution. The amount of S9 supernatant was 15 % v/v in the cultures. The concentrated co-factor solution yields the following concentrations in the S9 mix:
8 mM MgCl2
33 mM KCl
5 mM Glucose-6-phosphate
5 mM NADP
in 100 mM sodium-ortho-phosphate-buffer, pH 7.4.
During the experiment the S9 mix was stored in an ice bath. The S9 mix preparation was performed according to Ames et al.
Test concentrations with justification for top dose:
Nominal concentration: 33; 100; 333; 1000; 2500; and 5000 µg/plate
Vehicle / solvent:
Solvent: deionised water
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
Deionised water
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
With metabolic activation: S.typhimurium TA 1535, TA 100
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylene-diamine, 4-NOPD
Remarks:
With metabolic activation: S.typhimurium TA 1537, TA 98
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
Deinonised water
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
With metabolic activation: E.coli WP2 uvrA
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene, 2-AA
Remarks:
Without metabolic activation: TA 1535, TA 1537, TA 98, TA 100, WP2 uvrA
Details on test system and experimental conditions:
NUMBER OF REPLICATIONS:
- Number of cultures per concentration: Triplicate
- Number of independent experiments: Two

METHOD OF TREATMENT/ EXPOSURE:
- Test substance added in medium: Experiment I : In agar (plate incorporation); Experiment II: Preincubation

TREATMENT AND HARVEST SCHEDULE:
- Preincubation period: Yes Experiment II.
- Exposure duration/duration of treatment: 60 min

METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method: Background growth inhibition

METHODS FOR MEASUREMENTS OF GENOTOXICIY : Dose related and reproducible increase in the number of revertants or a biologically relevant and reproducible increase for at least one test concentration is induced.
Evaluation criteria:
Acceptability of the Assay:
The Salmonella typhimurium and Escherichia coli reverse mutation assay is considered acceptable if it meets the following criteria:
- regular background growth in the negative and solvent control
- the spontaneous reversion rates in the negative and solvent control are in the range of our historical data
- the positive control substances should produce a significant increase in mutant colony frequencies

Evaluation of Results:
A test article is considered positive if either a dose related and reproducible increase in the number of revertants or a biologically relevant and reproducible increase for at least one test concentration is induced.
A test article producing neither a reproducible and dose related increase in the number of revertants, nor a biologically relevant and reproducibly positive response at any one of the test points is considered non-mutagenic in this system.
A mutagenic response is described as follows:
A test article is considered mutagenic if in the strains TA 98, TA 100, and WP2 the number of reversions will be at least twice as high and in the strains TA 1535 and TA 1537 at least three times higher as compared to the spontaneous reversion rate (3,4).
Also, a dose-dependent and reproducible increase in the number of revertants is regarded as an indication of possibly existing mutagenic potential of the test article regardless whether the highest dose induced the above described enhancement factors or not.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid

Any other information on results incl. tables

No relevant toxic effects, evident as a reduction in the number of revertants, occurred in the est groups with and without metabolic activation. The plates incubated with the test article showed normal background growth up to 5000 µg/plate with and without metabolic activation in both independent experiments. No substantial increase in revertant colony numbers of any of the five tester strains was observed following treatment with FAT 40574/B at any dose level, neither in the presence nor absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. Appropriate reference mutagens were used as positive controls and showed a distinct increase of induced revertant colonies.

Applicant's summary and conclusion

Conclusions:
The test article did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used.
Executive summary:

A GLP-study was performed according to OECD test guideline 471 to investigate the potential of FAT 40574/B to induce gene mutations according to the plate incorporation test (experiment I) and the pre-incubation test (experiment II) using the Salmonella typhimurium strains TA 1535, TA 1537, TA 98 and TA 100 and in addition the Escherichia coli strain WP2 uvrA. The assay was performed in two independent experiments both with and without liver microsomal activation. Each concentration, including the controls, was tested in triplicate. The test article was tested at the following concentrations: 33; 100; 333; 1000; 2500 and 5000 µg/plate. No relevant toxic effects, evident as a reduction in the number of revertants, occurred in the test groups with and without metabolic activation. Slight, seemingly toxic effects occurred in strain TA 100 with metabolic activation in the first experiment. However, this effect is based upon a high solvent control value (105 colonies mean value versus 85 of the corresponding solvent control) and does represent statistical fluctuations rather than a true toxic effect. Another slight toxic effect was observed in strain TA 98 without metabolic activation in the second experiment. Since this effect was not really dose dependent, it was again judged as caused by statistical fluctuations. The plates incubated with the test article showed normal background growth up to 5000 µg/plate with and without metabolic activation in both independent experiments. No substantial increase in revertant colony numbers of any of the five tester strains was observed following treatment with FAT 40574/B at any dose level, neither in the presence nor absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. Appropriate reference mutagens were used as positive controls. They showed a distinct increase of induced revertant colonies. In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test article did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used.

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