L-Tyrosine, N-acetyl-3,5-dinitro-

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vitro

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:

2019

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 (incl. QA statement)

Type of study:

direct peptide reactivity assay (DPRA)

Test material

Test material information

Constituent 1

Reference substance name:

L-Tyrosine, N-acetyl-3,5-dinitro-

Cas Number:

20767-00-4

Molecular formula:

C11H11N3O8

IUPAC Name:

L-Tyrosine, N-acetyl-3,5-dinitro-

Test material form:

solid

In vitro test system

Details on the study design:

The study was performed in order to evaluate the reactivity of the test item L-Tyrosine, N-acetyl-3,5-dinitro- towards cysteine (Cys-) and lysine (Lys-) containing peptides. The test item was incubated for 22 h at 25 °C together with Cys- and Lys-peptides, respectively. The peptide concentration after the incubation was measured using HPLC-UV.
Three replicates were prepared using 1:10 and 1:50 molar ratio of the test item with the Cys- and Lys-peptide, respectively. Triplicate samples of the solvent without test item were incubated and measured simultaneously.

Results and discussion

In vitro / in chemico

Results

Results 1

Key result

Run / experiment:

other: Experiment 4

Parameter:

other: % Lys-peptide depletion

Value:

6.55

Results 2

Key result

Run / experiment:

other: Experiment 7

Parameter:

other: % Cys-peptide depletion

Value:

25.32

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

In conclusion, the DPRA prediction is “positive” with ≥ low reactivity according to the Cysteine 1:10/Lysine 1:50 prediction model in case of co-elution from the DB-ALM protocol n° 154. It can be stated that in this study and under the experimental conditions reported, the test item L-Tyrosine, N-acetyl-3,5-dinitro- possesses a skin sensitisation potential.

Executive summary:

All acceptance criteria were fulfilled; therefore, the test was considered valid.

The experiments 1 to 4 and 6 were not valid for the Cys-peptide assay, because the mean peptide concentration of the reference control C with acetonitrile/water (50/50 %, v/v) was not in the given range. Reason for this was the wrong sample preparation in the first six experiments.

For the Lys-peptide assay in the experiments 1 to 3 the mean peptide concentration of the positive control 2,3-Butanedione was not in the given range.

Experiment 4 was valid for the Lys-peptide assay and the results are reported here.

The fifth experiment was invalid for the Cys-peptide, because of a technical error during the HPLC measurement and thereby missing values for the positive control, the test item and some reference controls.

The seventh experiment was performed with the correct sample preparation and a valid result for the Cys-peptide could be obtained. The invalid experiments are not reported in this report, but the raw data are kept in the test facility in the GLP- archive.

Under the experimental conditions reported here, the test item shows co-elution with the respective peptide and no peak is detectable at 258 nm in both assays.

Co-elution means, the test item itself absorbs at 220 nm and has the same retention time as the Cys-peptide or Lys-peptide, respectively. Nevertheless, according to the DB-ALM protocol n° 154, the peaks could be integrated. But the baseline is not flat so the values will be considered estimates because the “area under the curve” cannot be determined with complete certainty. It is possible that the peak area appears to be larger than it really is, therefore the calculated percent depletion may be underestimated. So, the DPRA classification was made with the estimated values andcannot stand alone, for assessment it is necessary to combine the results with other complementary data and information.

In conclusion, under the experimental conditions reported here and with the estimated values, the DPRA-prediction is positive and the reactivity class ≥ Low.

No observations arousing doubts concerning the validity of the study were made.