bis(trifluoromethylsulfonyl)azanide;1-ethyl-3-methylimidazol-3-ium

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study plan dated: 29. Jan. 2018; Experimental starting date: 20. Feb. 2018; Experimental completion date: 02. Mar. 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 442D (In Vitro Skin Sensitisation: ARE-Nrf2 Luciferase Test Method)

Version / remarks:

Febr. 2015

GLP compliance:

yes (incl. QA statement)

Type of study:

activation of keratinocytes

Test material

Test material information

Constituent 1

Reference substance name:

1-ethyl-3-methyl-1H-imidazol-3-ium; trifluoro[(trifluoromethanesulfonylazanidyl)sulfonyl]methane

EC Number:

700-235-5

Cas Number:

174899-82-2

Molecular formula:

C8H11F6N3O4S2

IUPAC Name:

1-ethyl-3-methyl-1H-imidazol-3-ium; trifluoro[(trifluoromethanesulfonylazanidyl)sulfonyl]methane

Test material form:

liquid

Details on test material:

clear liquid, colorless

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: proionic GmbH; Lot.Nr.: 25PI208_12
- Expiration date of the lot/batch: MAy 2019
- Purity test date: EMIM+: 99.84 wt% HPLC; NTf2-: 99.95 wt% IC

STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature (20 +/- 5°C), keep away from humidity

In vitro test system

Details on the study design:

This in vitro study was performed to assess the potential of the test item 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide to activate the Nrf2 transcription factor by using the genetically modified keratinocyte cell-line “LuSens”
It employs the use of a reporter gene for luciferase placed under the control of the antioxidant response element (ARE) and hence monitors Nrf2 transcription factor activity. The measured endpoint is the up-regulation of luciferase activity after 48 h of incubation with the test substance at different concentrations. This up-regulation is an indicator for the activation of the Keap1/Nrf2/ARE signalling pathway . In order to conclude on the Nrf2 transcription factor activity of the test substance, at least two, but a maximum of three independent and valid experiments are performed.

Results and discussion

In vitro / in chemico

Results

Results 1

Key result

Run / experiment:

other: experiment I

Parameter:

other: Induction of Luciferase

Value:

1.1

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Results 2

Key result

Run / experiment:

other: experiment II

Parameter:

other: Induction of Luciferase

Value:

1.2

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Any other information on results incl. tables

Acceptability of experiment I and II:

Criteria	Found in experiment I	Found in experiment II
The average induction for the positive control should be ≥ 2.5 fold and it should have a relative viability of at least 70 %.	Positive controlFold induction: 5.0 Relative viability: 97.0 %	Positive controlFold induction: 4.5 Relative viability: 90.5 %
The induction triggered by the negative control and growth control should be < 1.5 fold as compared to the induction of the solvent control and the viability should be above 70%.	Negative control: Fold induction: 1.1 Relative viability: 112.5 % Growth control: Fold induction: 1.0 Relative viability: 121.1 %	Negative control: Fold induction: 1.0 Relative viability: 106.3 % Growth control: Fold induction: 1.0 Relative viability: 132.9 %
The average percentage standard deviation (luciferase induction) of the variability in at least 21 solvent control wells should be below 20 %.	8.36 %	10.46 %
At least 3 test concentrations must be within viability limits, i.e. have relative viability of at least 70 %.	9 concentrations are analysable	9 concentrations are analysable

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the experimental conditions of this study, the test item, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, was negative in the LuSens assay and is therefore considered not having the potential to activate the Nrf2 transcription factor (no sensitizing potential)

Executive summary:

This in vitro study evaluates the potential of the test item1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide to activate the Nrf2 transcription factor (sensitizing potential)by using the LuSens cell line. This test is part of a tiered strategy for the evaluation of skin sensitization potential. Thus, data generated with the present Test Guideline should be used to support the discrimination between skin sensitizers and non-sensitizers in the context of an integrated approach to testing and assessment.

The LuSens test is an ARE Reporter Gene Assay that was developed by the BASF SE (Ludwigshafen, Germany) and is based on the OECD 442D Guideline (KeratinoSens Assay). Since July 2017 a reviewed version of the OECD 442D is available, which includes the LuSens test. Therefore this study is performed in accordance to this draft OECD 442D with the title “In Vitro Skin Sensitisation assays addressing the AOP Key Event on: Keratinocyte activation”.

The assay included a cytotoxicity range finder test (CRFT) and two independent experiments (experiment I and II) with a treatment period of 48 h. The CRFT was performed to detect a potential cytotoxic effect of the test item. Based on the results of this test the concentrations for the two experiments were determined.

In the experiments, the highest nominal applied concentration (2000 µM) was chosen based on the results obtained in the CRFT. A geometric series (factor 1.2) of eleven dilutions thereof was prepared. Precipitation of the test item was not visible in any of the experiments.

DMSO (final concentration: 1 %) was used as solvent control and medium no. 3 as growth control. Lactic acid (5000 µM) was used as negative control and EGDMA (120 µM) as positive control.

No substantial and reproducible dose dependent increase in luciferase induction above 1.5 fold was observed in both experiments up to the maximal tested concentration of the test item.