[2,2,6,6-tetramethyl-4-(trimethylazaniumyl)piperidin-1-yl]oxidanyl chloride

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09.03.2018 to 14.08.2018

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 442C (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

direct peptide reactivity assay (DPRA)

Justification for non-LLNA method:

In order to reduce in vivo experiments, in chemico, in slico and/or in vitro methodes on skin sensitisation can be used. The DPRA test method is able to detect chemicals that cause skin sensitisation and may be used on its own to classify a chemical into UN GHS “Category 1”.
Data generated with this method may be not sufficient to conclude on the absence of skin sensitisation potential of chemicals and should be considered in the context of an integrated approach such as IATA, combining them with other complementary information e.g., derived from in vitro assays addressing other key events of the AOP.

Test material

Test material information

Constituent 1

Reference substance name:

[2,2,6,6-tetramethyl-4-(trimethylazaniumyl)piperidin-1-yl]oxidanyl chloride

EC Number:

814-375-0

Cas Number:

67036-09-3

Molecular formula:

C12H26N2OCl

IUPAC Name:

[2,2,6,6-tetramethyl-4-(trimethylazaniumyl)piperidin-1-yl]oxidanyl chloride

Test material form:

solid

In chemico test system

Details on the study design:

In the present study TMA-TEMPO was dissolved in dist. water, based on the results of the pre-experiments to obtain a stock solution of 100mM.
The test item solutions were incubated with the cysteine and lysine peptide solutions in glass vials using defined ratios of peptide to test item (1:10 cysteine peptide, 1:50 lysine peptide). The reaction solutions were left in the dark at 25 ± 2.5 °C for 24 ± 2 h before running the HPLC analysis. Reference controls, co-elution controls as well as the positive control were set up in parallel. After the 24 h ± 2 h incubation period but prior to the HPLC analysis samples were inspected for precipitation, turbidity or phase separation.

Results and discussion

Positive control results:

Phase separation was observed for the samples of the positive control including the co-elution control. Mean peptide depletion (Cystein): 70.09%; Mean peptide depletion (Lysine): 61.66%
Prediction Model 1 (Cysteine Peptide and Lysine Peptide / Ratio: 1:10 and 1:50): Mean peptide depletion: 65.88% (high reactivity, sensitiser); Prediction Model 2 (Cysteine Peptide / Test Item Ratio: 1:10): Mean peptide depletion: 65.88% (moderate reactivity, sensitiser)

In vitro / in chemico

Results

Results 1

Key result

Run / experiment:

other: Prediction Model 1 (Cysteine Peptide and Lysine Peptide / Ratio: 1:10 and 1:50)

Parameter:

other: mean peptide depletion [%]

Value:

5.75

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Remarks on result:

other: inconclusive

Results 2

Run / experiment:

other: Prediction Model 2 (Cysteine Peptide / Test Item Ratio: 1:10)

Parameter:

other: mean peptide depletion [%]

Value:

10.88

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Remarks on result:

other: not applicable

Other effects / acceptance of results:

DEMONSTRATION OF TECHNICAL PROFICIENCY: yes - historical data

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for vehicle control: reference control A, B, C pass the acceptance criteria for both peptides (Cysteine and Lysine)
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: yes
- Range of historical values: met acceptance criteria for positive control and reference controls A, B, C for both peptides (Cysteine and Lysine)

Any other information on results incl. tables

According to the evaluation criteria in the guideline, for test items with combined cysteine / lysine peptide depletion between 3% and 10% a second run should be considered. Therefore, no prediction can be made.

Applicant's summary and conclusion

Interpretation of results:

other: results can be used in an IATA to decide on classification or no classification for skin sensitisation

Remarks:

inconclusive

Conclusions:

In this study under the given conditions the test item showed minimal reactivity towards both
peptides. Due to the evaluation criteria in the guideline the prediction model does not apply and a
prediction cannot be made.
The data generated with this method may be not sufficient to conclude on the absence of skin
sensitisation potential of chemicals and should be considered in the context of integrated approach
such as IATA.