2-[4-(dimethylamino)phenyl]-3,6-dimethylbenzothiazolium chloride

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

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

Type of study:

other: Direct Peptide Reactivity Assay

Test material

Test material information

Constituent 1

Reference substance name:

2-[4-(dimethylamino)phenyl]-3,6-dimethylbenzothiazolium chloride

EC Number:

219-228-9

EC Name:

2-[4-(dimethylamino)phenyl]-3,6-dimethylbenzothiazolium chloride

Cas Number:

2390-54-7

Molecular formula:

C17H19N2S.Cl

IUPAC Name:

2-[4-(dimethylamino)phenyl]-3,6-dimethylbenzothiazolium chloride

Test material form:

solid: particulate/powder

Results and discussion

In vitro / in chemico

Results

Results 1

Run / experiment:

other: Cysteine Peptide Run

Parameter:

other: Mean Peptide Depletion

Value:

29.1

Positive controls validity:

valid

Remarks on result:

positive indication of skin sensitisation

Results 2

Run / experiment:

other: Lysine Peptide Run

Parameter:

other: Mean Peptide Depletion

Positive controls validity:

valid

Remarks on result:

not determinable

Other effects / acceptance of results:

The samples containing test item and lysine peptide had become solid after the incubation time. Therefore, no measurement was possible and no results concerning the lysine peptide depletion of the test item are reported

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

In this study under the given conditions the test item showed moderate reactivity towards the cysteine peptide. The test item can be classified as “sensitiser” in accordance with UN GHS “Category 1”.
The data generated with this method may be not sufficient to conclude on the skin sensitisation potential of chemicals and should be considered in the context of integrated approach such as IATA.

Executive summary:

The in chemico direct peptide reactivity assay (DPRA) enables detection of the sensitising potential of a test item by quantifying the reactivity of test chemicals towards synthetic peptides containing either lysine or cysteine.

In the present study Basic Yellow 1 was dissolved in water.

Based on a molecular weight of 318.86 g/mol a 100 mM stock solution was prepared. The test item solutions were tested by incubating the samples with the peptides containing either cysteine or lysine for 24 ± 2 h at 25 ± 2.5 °C. Subsequently samples were analysed by HPLC.

The samples containing test item and lysine peptide had become solid after the incubation time. Therefore, no measurement was possible and no results concerning the lysine peptide depletion of the test item are reported.

After the 24 h ± 2 h incubation period but prior to the HPLC analysis the cysteine peptide samples were inspected for precipitation, turbidity or phase separation. No precipitation, turbidity or phase separation was observed for the test item samples. A slight precipitation was observed for standard 1 and the positive control samples. Since the acceptance criteria for the linearity of the standard curve as well as for the depletion range of the positive control were fulfilled, the observed precipitations were regarded as insignificant.

No co-elution of test item with the cysteine peptide peak was observed. Since the lysine peptide samples could not be measured, sensitising potential of the test item was predicted only from the peptide depletion of the cysteine peptide by comparing the peptide concentration of the test item treated samples to the corresponding reference control C (RC C).

The 100 mM stock solution of the test item showed moderate reactivity towards the synthetic peptide. The mean depletion of the cysteine peptide was > 13.89% (29.15%). Based on the prediction model 2 the test item can be considered as sensitiser.

The 100 mM stock solution of the positive control (cinnamic aldehyde) showed high reactivity towards the synthetic peptides. The mean depletion of both peptides was 64.92%.

8.2. Conclusion

In this study under the given conditions the test item showed moderate reactivity towards the cysteine peptide. The test item can be classified as “sensitiser” in accordance with UN GHS “Category 1”.

The data generated with this method may be not sufficient to conclude on the skin sensitisation potential of chemicals and should be considered in the context of integrated approach such as IATA.