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Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in chemico

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:

2021

Report date:

2021

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Type of study:

direct peptide reactivity assay (DPRA)

Test material

Test material information

Constituent 1

Reference substance name:

Tricyclo[8.2.2.24,7]hexadeca-4,6,10,12,13,15-hexaene, 5,11,13,15-tetramethyl-

Cas Number:

205825-52-1

Molecular formula:

C20H24

IUPAC Name:

Tricyclo[8.2.2.24,7]hexadeca-4,6,10,12,13,15-hexaene, 5,11,13,15-tetramethyl-

Test material form:

solid: particulate/powder

In chemico test system

Details of test system:

cysteine peptide, (Ac-RFAACAA-COOH)

lysine peptide (Ac-RFAAKAACOOH)

Details on the study design:

Based on a molecular weight of 264.41 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.
All test item solutions were freshly prepared immediately prior to use.
For the 100 mM stock solution of the test item turbidity and precipitation was observed when diluted with the cysteine peptide solution. After the 24 h ± 2 h incubation period but prior to the HPLC analysis samples were inspected for precipitation, turbidity or phase separation. Precipitation was observed for
the samples of the test item (including the co-elution control). Samples were not centrifuged prior to
the HPLC analysis.
For the 100 mM stock solution of the test item turbidity and precipitation was observed when diluted
with the lysine peptide solution. After the 24 h ± 2 h incubation period but prior to the HPLC analysis
samples were inspected for precipitation, turbidity or phase separation.

Vehicle / solvent:

acetonitrile

Results and discussion

In vitro / in chemico

Results

Results 1

Group:

test chemical

Run / experiment:

mean

Parameter:

lysine depletion

Value:

0.28 %

Results 2

Group:

test chemical

Run / experiment:

mean

Parameter:

cysteine depletion

Value:

0.28 %

Any other information on results incl. tables

Precipitation was observed for
the samples of the test item (including the co-elution control). Slight Turbidity was observed for the
samples of the positive control (excluding the co-elution control). Samples were not centrifuged prior
to the HPLC analysis. Since the acceptance criteria for the depletion range of the positive control were
fulfilled, the observed turbidity was regarded as not relevant.
Precipitation of the test item with both peptide peaks was observed. Therefore, the given peak areas
and corresponding peptide values can only be considered as an estimation of the peptide depletion.
The stock solution of the test item showed minimal reactivity towards the synthetic peptides. The mean
depletion of both peptides was  6.38% (0.28%). Since precipitation was observed, a test item
concentration of 100 mM as well as the full contact of peptide and test item is not guaranteed.
According to the evaluation criteria in the guideline, no firm conclusion on the lack of reactivity should be drawn from a negative result, if a test chemical is tested in concentration < 100 mM. Therefore, no
prediction can be made.

Applicant's summary and conclusion

Interpretation of results:

study cannot be used for classification

Conclusions:

Due to the observed precipitation the prediction model does not apply and a prediction cannot be
made.
The data generated with this test should be considered in the context of integrated approached such as IATA, combining the result with other complementary information, e.g. derived from in vitro assays addressing other key events of the skin sensitisation AOP.