Reaction mass of isomers disodium 8-(2-{4-[benzyl(ethyl)amino]-2-methylphenyl}diazen-1-yl)-5-(2-{2,5-dimethyl-4-[2-(3-sulfonatophenyl)diazen-1-yl]phenyl}diazen-1-yl)naphthalene-2-sulfonate, disodium 5-(2-{4-[benzyl(ethyl)amino]-2-methylphenyl}diazen-1-yl)-8-(2-{2,5-dimethyl-4-[2-(3-sulfonatophenyl)diazen-1-yl]phenyl}diazen-1-yl)naphthalene-2-sulfonate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-04-02 to 2013-05-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5395 (In Vivo Mammalian Cytogenetics Tests: Erythrocyte Micronucleus Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

micronucleus assay

Test material

Test material information

1

Reference substance name:

tetrasodium 5-[(1E)-2-{4-[benzyl(ethyl)amino]-2-methylphenyl}diazen-1-yl]-8-[(1E)-2-{2,5-dimethyl-4-[(1E)-2-(3-sulfonatophenyl)diazen-1-yl]phenyl}diazen-1-yl]naphthalene-2-sulfonate 8-[(1E)-2-{4-[benzyl(ethyl)amino]-2-methylphenyl}diazen-1-yl]-5-[(1E)-2-{2,5-dimethyl-4-[(1E)-2-(3-sulfonatophenyl)diazen-1-yl]phenyl}diazen-1-yl]naphthalene-2-sulfonate

EC Number:

700-946-0

Molecular formula:

C40H35N7Na2O6S2

IUPAC Name:

tetrasodium 5-[(1E)-2-{4-[benzyl(ethyl)amino]-2-methylphenyl}diazen-1-yl]-8-[(1E)-2-{2,5-dimethyl-4-[(1E)-2-(3-sulfonatophenyl)diazen-1-yl]phenyl}diazen-1-yl]naphthalene-2-sulfonate 8-[(1E)-2-{4-[benzyl(ethyl)amino]-2-methylphenyl}diazen-1-yl]-5-[(1E)-2-{2,5-dimethyl-4-[(1E)-2-(3-sulfonatophenyl)diazen-1-yl]phenyl}diazen-1-yl]naphthalene-2-sulfonate

Test material form:

solid: particulate/powder

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, Germany
- Age at study initiation: minimum 7 weeks
- Assigned to test groups randomly: yes
- Housing: 5 animals of identical sex per cage, IVC cage (Polysulphone), Type II L
- Diet: Altromin 1324 maintenance diet for rats and mice
- Water: tap water, sulphur acidified to pH value of approx. 2.8 (drinking water, municipal residue control, micro-biologically controlled at frequent intervals)
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 55 ± 10%
- Air changes (per hr): at least 10 x per hour
- Photoperiod (hrs dark / hrs light): artificial light 6:00 - 18:00

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

- Vehicle/solvent used: 0.9% NaCl
- Justification for choice of solvent/vehicle: The solvent was chosen based on best solubility of the test item and according to its relative non-toxicity for the animals.
- Concentration of test material in vehicle: 25 mg/mL (1 MTD), 12.5 mg/mL (0.5 MTD), 5 mg/mL (0.2 MTD)
- Amount of vehicle (if gavage or dermal): 10 mL per kg body weight
- Lot/batch no.: 12174417 Braun

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

The test item was suspended in 0.9% NaCl within 1 h before treatment. All animals received a single volume ip of 10 mL/kg bw.

Frequency of treatment:

The animals received the test item once ip.

Post exposure period:

Sampling of the peripheral blood was carried out on animals 44 h (all control and dose groups) and 68 h (negative control, 1 MTD group) after treatment.

Doses / concentrations

Remarks:

Doses / Concentrations:
three dose groups: 1 MTD (250 mg/kg bw), 0.5 MTD (125X mg/kg bw), 0.2 MTD (50 mg/kg bw)
Basis:
other: suspension in 0.9% NaCl

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Positive control(s):

cyclophosphamide
- Justification for choice of positive control: clastogenic control substance, good stability at room temperature, broad basis of historical laboratory data
- Route of administration: intraperitoneal
- Doses / concentrations: 40 mg/kg body weight

Examinations

Tissues and cell types examined:

peripheral blood erythrocytes

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION:
A preceding study on toxicity was performed with the same strain and under identical conditions as in the main study. Three animals of each sex were treated ip for detection of the maximum tolerable dose. The maximum dose that was applied was 2000 mg/kg bw according the OECD 474 guideline. The maximum volume which was administered was 10 mL/kg bw. The highest dose group evaluated in the main experiment (250 mg/kg bw) was based on the toxicity observed in the pre-experiment.

METHOD OF ANALYSIS:
Evaluation of all samples, including those of positive and negative controls, was performed using a flow cytometer (FACScan, BD Biosciences). Anti-CD71 antibodies were labelled with Fluorescein-isothiocyanate (FITC), anti-CD61 antibodies were labelled with Phycoerythrin (PE). Particles were differentiated using Forward Scatter (FSC) and Side Scatter (SSC) parameters of the flow cytometer. Fluorescence intensity were recorded on the FL1, FL2 and FL3 channels for FITC, PE and PI respectively. At least 10000 immature erythrocytes per animal were scored for the incidence of micronucleated immature erythrocytes. To detect an eventually occurring cytotoxic effect of the test item the ratio between immature and mature erythrocytes was determined. The results were expressed as relative PCE (rel. PCE = proportion of polychromatic (immature) erythrocytes among total erythrocytes).

Evaluation criteria:

There are several criteria for determining a positive result:
- dose-related increase in the number of micronucleated cells and/or
- biologically relevant increase in the number of micronucleated cells for at least one of the dose groups.
According to the OECD guideline, the biological relevance as well as the statistical significance of the results are the criterion for the interpretation.
A test item is considered to be negative if there is no biologically relevant and/or statistically significant increase in the number of micronucleated cells at any dose level.

Statistics:

For the statistics the nonparametric Mann-Whitney Test was used. However, both biological relevance and statistical significance were considered together.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Clinical signs of toxicity in test animals:
In the pre-experiment a concentration of 200 mg/mL of the test item was evaluated. One male mouse received a single dose of 2000 mg/kg bw ip and showed signs of toxicity such as reduction of spontaneous activity, catalepsis, constricted abdomen, piloerection, eye closure, muscle twitches, half eyelid closure and prone position. Additionally, the animal’s skin was coloured blue. The animal died 24 hours after treatment. One male mouse received a single dose of 1000 mg/kg bw ip and showed signs of toxicity such as reduction of spontaneous activity, catalepsis, constricted abdomen, piloerection, half eyelid closure, eye closure and lacrimation. After 24 hours the animals had light constipation and the little dung that was exuded was hard and dry. Additionally, the skin was coloured blue. One male mouse received a single dose of 500 mg/kg bw and showed signs of toxicity such as reduction of spontaneous activity, catalepsis, constricted abdomen, piloerection, half eyelid closure, eye closure and lacrimation. Additionally, the skin was blue coloured. One additional male mouse received a single dose of 1000 mg/kg bw ip and showed signs of toxicity such as reduction of spontaneous activity, catalepsis, constricted abdomen, piloerection, uncoordinated movements and half eyelid closure. Additionally, the animal’s skin was coloured blue. Based on animal welfare aspects the animal was euthanized 24 hours after the treatment. Three male and three female mice received a single dose of 500 mg/kg bw and showed signs of toxicity such as reduction of spontaneous activity, catalepsis, constricted abdomen, piloerection, eye closure, uncoordinated movements, half eyelid closure, chromodacryorrhea, kyphosis, opisthotonos, half eyelid closure and prone position. Additionally, the animals` skin was coloured blue. Based on animal welfare aspects the animals were euthanized 48 hours after the treatment. Three male and three female mice received a single dose of 250 mg/kg bw ip and showed toxicity such as reduction of spontaneous activity, catalepsis, constricted abdomen, piloerection, half eyelid closure and uncoordinated movements. Additionally, the animals` skin was coloured blue.
Due to the results obtained in the pre-experiment 250 mg/kg bw was chosen as maximum tolerable dose (1 MTD) in the main experiment.

RESULTS OF DEFINITIVE STUDY
- Toxicity in the main experiment:
250 mg/kg bw was tested as the maximum tolerable dose (1 MTD) in the main experiment. The volume administered was 10 mL/kg bw ip.
All animals treated with the highest dose group (1 MTD) showed moderate toxic effects. After 44 h no toxic symptoms were observed anymore, except that the animals were coloured blue. Animals treated with 125 mg/kg bw (0.5 MTD) showed the same signs of toxicity as displayed for the 1 MTD dose group animals. After 44 h no toxic symptoms were observed anymore, except a moderate piloerection and blue skin colouration. The animals treated with 50 mg/kg bw (0.2 MTD) showed the same toxic effects as mentioned for the 0.5 MTD dose group except prone position. The signs of toxicity were mildly expressed. After 24 h no toxic symptoms were observed anymore, except a mild piloerection and blue skin colouration.

- Induction of micronuclei (for Micronucleus assay):
The negative controls (44 h and 68 h) evaluated were within the range of the historical control data of the negative control (0.10 – 0.34%,). The mean values of micronuclei observed for the negative control (44 h) were 0.22% (male mice) and 0.25% (female mice). The mean values for the 68 h negative control were 0.19% (male mice) and 0.20% (female mice).
The mean values of micronuclei observed after treatment with 0.2 MTD were 0.20% (male mice) and 0.25% (female mice). The values were within the range of the corresponding negative control as well as within the range of the historical negative control data.
The mean values noted for the 0.5 MTD dose group were 0.11% (male mice) and 0.13% (female mice). The value observed in the male and female group were significantly decreased as compared to the corresponding negative control. However, both values were within the range of the historical negative control data.
The dose group treated with 1 MTD (44 h treatment) showed mean values of 0.17% (male mice) and 0.18% (female mice). The value observed in the male group was slightly decreased compared to the corresponding negative control, but this decrease was not statistically significant. Additionally, the value was within the range of the historical negative control data. The value observed in the female group was within the range of the corresponding negative control as well as within the range of the historical negative control data.
The mean values observed for the 1 MTD 68 h treatment were 0.25% (male mice) and 0.23% (female mice). These values were within the range of the corresponding negative control as well as within the range of the historical negative control data.
No biologically relevant increase of micronuclei was found after treatment with the test item in any of the dose groups evaluated.

- Ratio of PCE/NCE (for Micronucleus assay):
The negative controls (44 h, 68 h) were within the range of the historical control data of the negative control (1.19 - 4.30). The mean values noted for the 44 h negative control were 1.95 (male mice) and 2.15 (female mice). The mean values detected for the 68 h negative control were 2.64 (male mice) and 2.88 (female mice).
The animal group treated with 0.2 MTD showed mean values of the relative PCE of 2.18 (male mice) and 1.69 (female mice). The value observed in the male group was slightly increased and the value noted in the female group was slightly decreased as compared to the corresponding negative control. However this decrease/increase was not statistically significant. Moreover the mean values were within the range of the historical control data.
The dose groups which were treated with 0.5 MTD showed mean values of the relative PCE of 1.44 (male mice) and 2.05 (female mice). The values observed in the male and female group were slightly decreased compared to the corresponding negative control. However, the values were not statistically significant and they were within the range of the historical control data.
The animals who received 1 MTD (44 h treatment) showed mean values of 1.32 (male mice) and 1.64 (female mice). The values observed in the male and female group were slightly decreased compared to the corresponding negative control. However, the values were not statistically significant and they were within the range of the historical control data.
The animal group which was treated with 1 MTD (68 h treatment) showed mean values of the relative PCE of 0.70 (male mice) and 0.79 (female mice). The values observed in the male and female group were significantly decreased compared to the corresponding negative control.

- Statistical evaluation:
The nonparametric Mann-Whitney Test was performed to verify the results. No statistically significant increases/decreases (p<0.05) of cells with micronuclei were noted in the dose groups of the test item evaluated, except the value observed for the 0.5 MTD male and female group. These groups were significantly decreased as compared with the corresponding control. However the values were within the range of the historical negative control data. Based on this data this decrease was regarded as not biologically relevant.

Applicant's summary and conclusion

Conclusions:

In conclusion, it can be stated that during the study and under the experimental conditions reported, the test item did not induce structural and/or numerical chromosomal damage in the immature erythrocytes of the mouse.
Therefore, the test item is considered to be non-mutagenic with respect to clastogenicity and/or aneugenicity in the Mammalian Erythrocyte Micronucleus Test.

Executive summary:

In a NMRI mouse peripheral blood micronucleus assay, five male and female animals per dose group were treated ip with test item at doses of 250, 125 and 50 mg/kg bw.  Peripheral blood cells were harvested at 44 h (all dose and control groups) and 68 h (negative control and 1 MTD group) post-treatment.  The vehicle was 0.9% NaCl. The animals received the test item once ip.
There were signs of toxicity during the study.  The animals treated with doses of 0.2 and 0.5 MTD showed dose-depended mild and moderate signs of systemic toxicity. The animals treated with a dose of 1 MTD showed moderate signs of systemic toxicity such as reduction of spontaneous activity, prone position, constricted abdomen, piloerection, opisthotonos, kyphosis, half eyelid closure, catalepsis and eye closure. Additionally, the animals were coloured blue. One male animal (1 MTD group) died 24 hours after treatment and was replaced by a reserve animal. Test item was tested at an adequate dose based on OECD 474. The positive control induced the appropriate response. There was no significant increase in the frequency of micronucleated polychromatic erythrocytes in peripheral blood cells after any treatment time.
This study is classified as acceptable. This study satisfies the requirement for Test Guideline OPPTS 870.5395; OECD 474 for in vivo cytogenetic mutagenicity data.