(2RS,3RS)-3-(2-chlorophenyl)-2-(4-fluorophenyl)-[(1H-1,2,4-triazol-1-yl)methyl]oxirane

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

not specified

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian erythrocyte micronucleus test

Test material

Test material information

Constituent 1

Reference substance name:

(2RS,3RS)-3-(2-chlorophenyl)-2-(4-fluorophenyl)-[(1H-1,2,4-triazol-1-yl)methyl]oxirane

EC Number:

406-850-2

EC Name:

(2RS,3RS)-3-(2-chlorophenyl)-2-(4-fluorophenyl)-[(1H-1,2,4-triazol-1-yl)methyl]oxirane

Cas Number:

133855-98-8

Molecular formula:

C17 H13 Cl F N3 O

IUPAC Name:

1-{[(2R,3R)-3-(2-chlorophenyl)-2-(4-fluorophenyl)oxiran-2-yl]methyl}-1H-1,2,4-triazole

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River GmbH, WIGA, 8741 Sulzfeld, Germany
- Age at study initiation: not specified
- Weight at study initiation: 28 g (mean)
- Assigned to test groups randomly: yes (with the help of an appropriate computer program)
- Fasting period before study: not specified
- Housing: 5 animals/cage during acclimation period; single housing during test period
- Diet: Kliba Haltungsdiät, ad libitum
- Water: drinking water, ad libitum
- Acclimation period: approx. 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 30 - 70
- Air changes (per hr): not specified
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: not specified

Administration / exposure

Route of administration:

oral: unspecified

Vehicle:

- Vehicle(s)/solvent(s) used: aqueous 0.5 % CMC formulation
- Justification for choice of solvent/vehicle: not specified
- Concentration of test material in vehicle: 25 g/100 mL (high dose group), 5 g/100 mL (mid dose group) or 1 g/100 mL (low dose group)
- Amount of vehicle (if gavage or dermal): 20 mL/kg bw

Details on exposure:

- applied dosage volume: 20 mL/kg bw (vehicle group and dosage groups), 10 mL/kg bw (positive control)


PREPARATION OF DOSING SOLUTIONS:

Frequency of treatment:

one single treatment

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

200 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

5 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

high dose group: 15
other treatment groups, vehicle control group and positive control group cyclophosphamide: 5
positive control group vincristine: 3 males and 2 females

Control animals:

yes, concurrent vehicle

Positive control(s):

cyclophosphamide, dissolved in aqua dest.
- Justification for choice of positive control(s): positive control for clastogenicity
- Route of administration: oral
- Doses / concentrations: 20 mg/kg bw in a volume of 10 mL/kg bw

vincristine, dissolved in aqua dest.
- Justification for choice of positive control(s): positive control for spindle poison effects
- Route of administration: intraperitoneal
- Doses / concentrations: 0.15 mg/kg bw in a volume of 10 mL/kg bw

Examinations

Tissues and cell types examined:

bone marrow

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: The doses were selected based on the results of a pretest for the determination of the acute oral toxicity. Herein, the highest applicable dose of 5000 mg/kg bw was survived by all animals but led to signs of toxicity such as irregular respiration, apathy and abdominal position. Therefore, a dose of 5000 mg/kg bw was selected as the highest dose in the present cytogenetic study. 1000 mg/kg bw and 200 mg/kg bw were administered as further doses.

TREATMENT AND SAMPLING TIMES (in addition to information in specific fields): sacrifice intervals: 16 h (high dose group), 24 h (all groups), 48 h (high dose group)

DETAILS OF SLIDE PREPARATION: The two femora were prepared from the animals and all soft tissues were removed. After cutting off the epiphyses, the bone marrow was flushed out of the diaphysis into a centrifuge tube using a cannula filled with fetal calf serum (37°C; about 2 mL/femur). The suspension was mixed thoroughly with a pipette, centrifuged at 1500 rpm for 5 minutes, the supernatant
was removed except for a few drops and the precipitate was resuspended. 1 drop of this suspension was dropped onto clean microscopic slides using a Pasteur pipette. Smears were prepared using slides with ground edges, the preparations were dried in the air and subsequently stained. The slides were stained in eosin and methylene blue solution for 5 minutes, rinsed in aqua dest. and then placed in fresh aqua dest. for 2 or 3 minutes. They were finally stained in Giemsa solution for 12 minutes. After being rinsed twice in aqua dest. and clarified in xylene, the preparations were embedded in Corbit-Balsam.

METHOD OF ANALYSIS: In general, 1000 polychromatic erythrocytes from each of the male and female animals of every test group were evaluated and investigated for micronuclei. Normochromatic erythrocytes (= normocytes) were also scored. The following parameters were recorded:
- number of polychromatic erythrocytes
- number of polychromatic erythrocytes containing micronuclei
- number of normochromatic erythrocytes
- number of normochromatic erythrocytes containing micronuclei
- ratio of polychromatic to normochromatic erythrocytes
- number of small micronuclei (d < D/4) and of large micronuclei (d >= D/4) (d = diameter of micronucleus, D = cell diameter)

Statistics:

A detailed statistical evaluation was not necessary to perform as the rate of micronucleated polychromatic erythrocytes after test substance treatment was nearly in the range of the actual control values and within the range of that of the historical control values.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RESULTS OF DEFINITIVE STUDY
- Clinical examination: at 200 mg/kg bw irregular respiration; at 1000 mg/kg bw irregular respiration and apathy, abdominal position (in a few cases); at 5000 mg/kg bw irregular respiration, abdominal position, apathy, staggering (in a few cases), poor general state, 4 animals died; no clinical signs were observed on the day after treatment
- Induction of micronuclei:
vehicle control - 1.6 % polychromatic erythrocytes containing micronuclei after the 24-hour sacrifice interval;
high dose group (5000 mg/kg bw) - 1.8 %, 2.3 % and 1.3 % polychromatic erythrocytes containing micronuclei were found after 16 h, 24 h and after 48 h, respectively;
mid dose group (1000 mg/kg bw) - 1.5 % polychromatic erythrocytes containing micronuclei were found after the 24-hour sacrifice interval;
low dose group (200 mg/kg bw) - 2.8 % polychromatic erythrocytes containing micronuclei were found after the 24-hour sacrifice interval;
positive control cyclophosphamide - 16.1 % polychromatic erythrocytes containing exclusively small micronuclei after the 24-hour sacrifice interval;
positive control vincristine - 98.6 % polychromatic erythrocytes containing the expected amount of large micronuclei after the 24-hour sacrifice interval;
The number of normochromatic erythrocytes containing micronuclei did not differ to any appreciable extent in the negative control or in the various dose groups at any of the sacrifice intervals;
No inhibition of erythropoiesis induced by the treatment of mice with the test substance was detected.
- Ratio of PCE/NCE: The ratio of polychromatic to normochromatic erythrocytes was always in the same range as that of the control values in all dose groups.