D-2-hydroxy-2-phenylacetic acid

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

see chapter 13 read across justification

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 442C (In Chemico Skin Sensitisation Assays addressing the Adverse Outcome Pathway key event on covalent binding to proteins)

GLP compliance:

yes (incl. QA statement)

Type of study:

other: Direct peptide binding assay

Test material

Test material information

Constituent 1

Reference substance name:

L-2-hydroxy-2-phenylacetic acid

EC Number:

210-276-6

EC Name:

L-2-hydroxy-2-phenylacetic acid

Cas Number:

611-71-2

Molecular formula:

C8H8O3

IUPAC Name:

hydroxy(phenyl)acetic acid

Details on test material:

- Name of test material (as cited in study report): L-2-Hydroxy-2-phenylacetic acid
- Physical state: solid (white)
- Analytical purity: 99.972 area%
- Lot/batch No.: 12-0001

In chemico test system

Details of test system:

cysteine peptide, (Ac-RFAACAA-COOH)

lysine peptide (Ac-RFAAKAACOOH)

Details on the study design:

The test substance was prepared as a 100 mM stock solution in acetonitrile just prior to incubation with the synthetic peptides.
The peptides are custom material (Supplier: GenScript, Piscataway, NJ, USA and/or RS Synthesis, Louisville KY, USA) containing. Because the test substance preparation was incubated with the peptide shortly after preparation, no analysis of the test substance in the vehicle was performed.
The test substance was solved in a suitable vehicle. Three samples of the test substance were incubated with each peptide. Additionally triplicates of the concurrent vehicle control (= NC) were incubated with the peptides. The remaining non-depleted peptide concentration was determined thereafter by HPLC with gradient elution and UV-detection at 220 nm. In addition calibration samples of known peptide concentration, prepared from the respective peptide stock solution used for test-substance incubation, were measured in parallel with the same analytical method.
The samples were prepared in triplicates for each peptide. The C-containing peptide was incubated with the test substance in a ratio of 1:10 (0.5 mM peptide, 5 mM test substance) and
the K-containing peptide in a ratio of 1:50 (0.5 mM peptide, 25 mM test substance). The samples were prepared in suitable tubes, capped tightly and incubated at 25°C ± 2.5°C in the dark for 24 +/- 2 hours. Prior to HPLC analysis the samples were visually investigated for any precipitate that may have formed during the exposure period. The HLPC analysis of the batch of samples started about 24 hours after sample preparation and the analysis time itself did not exceed 30 hours.
The mean peptide depletion of a test substance was calculated as the mean value of Ccontaining peptide depletion and K-containing peptide depletion. According to the classification tree model described by Gerberick et al. for substances with known molecular weight highly reactive test substance (mean peptide depletion > 42.47 %) is predicted to be a strong sensitizer, a moderately reactive test substance (22.62 % < mean peptide depletion < 42.47 %) a moderate sensitizer, a test substance of low reactivity (8.11 % < mean peptide depletion < 22.62 %) a weak sensitizer.

Vehicle / solvent:

acetonitrile

Positive control:

other: Ethylene glycol dimethacrylate (EGDMA; CAS: 97-90-5), prepared as a 50 mM solution in acetonitrile

Results and discussion

Positive control results:

All peptide was depleted by the positive control substance Ethylene glycol dimethacrylate.

In vitro / in chemico

Results

Group:

test chemical

Parameter:

other: C-peptide and K-peptide

Value:

0.79 %

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Remarks:

0.79% mean peptide depletion (1.57% cysteine peptide depletion -0.69% lysine peptide depletion)

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Negative depletions were considered to be “zero” for calculation of the mean peptide depletion, which was thus calculated to be 0.79%.
No co-elution of test substance and peptides was noticed.

Executive summary:

The mean Cysteine-peptide depletion, caused by the test substance was determined to be 1.57%.
The mean Lysine-peptide depletion, caused by the test substance was determined to be -0.69%.
Based on the observed results and applying the prediction model proposed in Gerberick et. al (2007) it was concluded that L-2-Hydroxy-2-phenylacetic acid shows a minimal chemical reactivity in the DPRA under the test conditions chosen.