1,3-diphenyl-2-thiourea

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian cell study: DNA damage and/or repair

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Waiting for ECHA approval

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 489 (In vivo Mammalian Alkaline Comet Assay)

GLP compliance:

yes

Type of assay:

mammalian comet assay

Test material

Test material information

Constituent 1

Reference substance name:

1,3-diphenyl-2-thiourea

EC Number:

203-004-2

EC Name:

1,3-diphenyl-2-thiourea

Cas Number:

102-08-9

Molecular formula:

C13H12N2S

IUPAC Name:

1,3-diphenyl-2-thiourea

Test material form:

solid: particulate/powder

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

Rodents have shown their sensitivity to many genotoxic agents by a significant increase in DNA damage. Rodents are recommended by OECD for this test.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River France origin, Saint-Germain-sur-l’Arbresle, FRANCE
- Age at study initiation:
- Weight at study initiation: Male rats: 200 g and 303 g. Female rats: 175 to 193 g.
- Assigned to test groups randomly: yes
- Fasting period before study: No
- Housing: polypropylene cages
- Diet: A04C-10 from SAFE (batch 21217) ad libitum
- Water: Drinking water, softened by reverse osmosis and filtered on 0.22 µm membrane ad libitum
- Acclimation period: 13 days before the main experiment

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 30-70 %
- Photoperiod: 12h/12h

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil
- Justification for choice of solvent/vehicle: standard vehicle compatible with the test item
- Concentration of test material in vehicle: 200, 100 and 50 mg/mL
- Amount of vehicle: 10 mL/kg
- Lot/batch no.: Sigma, batch MKCN 9742
- Purity: 99.7 % w/w

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Preparations were done 5 days before the 1st treatment.

Duration of treatment / exposure:

24 hours

Frequency of treatment:

2 successive administrations at 24-hour intervals

Post exposure period:

Samples were taken 2 to 6 hours after the last treatment

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Methylmethane sulfonate (positive control)

Doses / concentrations 2

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

500 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Doses / concentrations 5

Dose / conc.:

2 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

3 animals / sex / dose (preliminary testing)
5 animals / dose (main experiment)

Control animals:

yes, concurrent vehicle

Positive control(s):

methylmethanesulfonate

- Justification for choice of positive control(s): in accordance with the OECD Testing Guideline
- Route of administration: gavage
- Doses / concentrations: 100 mg/kg bw

Examinations

Tissues and cell types examined:

liver, glandular stomach and duodenum

Results and discussion

Test results

Key result

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

The potential genotoxic activity of the test item DPTU was investigated for genotoxic potential by the means of in vivo comet assay under alkaline conditions (SCGE) in the liver, glandular stomach and duodenum, in CD Sprague-Dawley rats, according to OECD Guidelines (No. 489, 2016). Animals were treated orally (gavage) once a day for 2 consecutive days, 24 hours apart, up to the top dose recommended of 2000 mg/kg b.w..
The control of concentrations of DPTU in treatment preparations was performed in a GLP-compliant laboratory following a validated method. The results are reliable.
The results of the assays for DPTU in treatment preparations were satisfactory. In addition DPTU was not detected in the solvent.
The acceptance criteria for the assay were fulfilled. The current study was valid.
Under our experimental conditions, the test item does not present DNA strand breaks and/or alkali-labile sites inducer activities toward the liver, glandular stomach and duodenum from CD Sprague-Dawley male rats.
As a conclusion, DPTU induced no genotoxic activity under these experimental conditions.

Executive summary:

The potential genotoxic activity of DPTU was assessed using the in vivo comet assay in the liver, glandular stomach and duodenum in male rats. The actual treatment was carried out by oral route (gavage), using 2 successive administrations at 24-hour intervals with the maximum recommended dose, i.e. 2000 mg/kg b.w..

In the preliminary assay performed on 3 males and 3 female rats, the highest dose of 2000 mg/ kg b.w. / day (x2) per os induced no mortality.
Otherwise, a slight decrease in spontaneous motor activity was observed 2 to 24 hours after the 1st treatment in all animals.
Between 15 minutes and up to 4 hours after the 2nd administration, a slight to moderate decrease in spontaneous motor activity was noted in males and a slight decrease in spontaneous motor activity was observed in females. A slight decrease in spontaneous motor activity was noted in all animals more than after 6 hours after the 2nd administration
Fifteen minutes after the 2nd administration, 1 male was slightly flaccid.
Noteworthy, the animals lost some weight, but the decrease remained below 10% when compared to the day before.
At 1250 mg/kg b.w./day (x2), no clinical sign was noted.
The dose of 2000 mg/kg that induced no redhibitory clinical sign was retained as the top dose to be tested in the main genotoxicity experiment. Two lower doses of 1000 and 500 mg/kg b.w./day were also tested.
Therefore, the main experiment was done in male rats since no obvious differences were observed between male and female animals during the preliminary study.

In the main study, no statistically or biologically significant increase in the mean of medians of percentage of DNA in tail per slide was observed at the 3 tested doses of 2000, 1000 and 500 mg/kg b.w./day (x 2) of DPTU in liver of CD Sprague-Dawley male rats. It was concluded that DPTU is not genotoxic toward liver from CD Sprague-Dawley male rats as
investigated by the in vivo Comet assay.

No statistically or biologically significant increase in the mean of medians of percentage of DNA in tail per slide was observed at the 3 tested doses of 2000, 1000 and 500 mg/kg b.w./day (x 2) of DPTU in glandular stomach of CD Sprague-Dawley male rats. It was concluded that DPTU is not genotoxic toward glandular stomach from CD Sprague-Dawley male rats as investigated by the in vivo Comet assay.

No statistically or biologically significant increase in the mean of medians of percentage of DNA in tail per slide was observed at the 3 tested doses of 2000, 1000 and 500 mg/kg b.w./day (x 2) of DPTU in duodenum of CD Sprague-Dawley male rats.
It was concluded that DPTU is not genotoxic toward duodenum from CD Sprague-Dawley male rats as investigated by the in vivo Comet assay.

The control of concentrations of DPTU in treatment preparations was performed in a GLP-compliant laboratory following a validated method. The results are reliable.
The results of the assays for DPTU in treatment preparations were satisfactory. In addition DPTU was not detected in the solvent.
The acceptance criteria for the assay were fulfilled. The current study was valid.

As a conclusion, DPTU induced no genotoxic activity under these experimental conditions.