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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in chemico
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP-guideline study, tested with the source substance 2-amino-2-methyl-1,3-propanediol (CAS 115-69-5). In accordance to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.
Justification for type of information:
The justification for category approach/read-across has been attached in section 13 of this IUCLID. In the enclosed document arguments are given for a category approach for four 2-amino-1,3-propane-diols. These substances share a common propane backbone with an amine group at 2-carbon position and primary alcohols at 1 and 3 positions. The members of the aminopropanediol category are: 2-amino-1,3-propanediol (APD, CAS No. 534-03-2), 2-amino-2-methyl-1,3-propane-diol (AMPD, CAS No. 115-69-5), 2-amino-2-ethyl-1,3-propanediol (AEPD, CAS No. 115-70-8), and 2-amino-2-(hydroxymethyl)-1,3-propanediol (trometamol, CAS No. 77-86-1).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Principles of method if other than guideline:
To test direct peptide reactivity which is a key pathway leading to skin sensitisation, the test substance was investigated for peptide depletion by chemical reaction. The assay method established by Natsch and Gfeller (2008) was validated and improved in the testing facility and utilised in this study.
GLP compliance:
yes
Type of study:
other: peptide binding assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): XU-12398.00
- Molecular formula (if other than submission substance): C4H11NO2
- Molecular weight (if other than submission substance): 105.1
- Analytical purity: 99.9%

In chemico test system

Details on study design:
Test system: The test system consists of a model peptide selected from an endogenous human protein expressed in skin tissue. The peptide consists of 7 amino acids and has an acetylated N-terminus. Sequence: Ac-NKKCDLF; Purity: 95.9% (HPLC-UV)

Results and discussion

In vitro / in chemico

Results
Key result
Remarks on result:
other: Under the test conditions, there is no evidence that the test substance contains direct protein reactivity which would cause skin sensitisation.

Any other information on results incl. tables

The test substance was completely soluble in acetonitrile and was not precipitated by mixing with peptide solutions. After 24 h incubation, there was no colour change or a precipitate observed from the test substance.

The test article did not have any UV absorbance at 220 nm through entire HPLC chromatography and therefore there was no interference with HPLC-UV analyses for peptides. Furthermore, the test substance did not interfere with the MS detections used in the test system that were monitoring higher than 700.0 m/z.

Using the established calibration curve, the concentrations of free peptide were calculated for each sample (Table 1). Average peptide depletion by the test substance was 4.22 ± 1.84%. Negative and positive controls resulted in 4.83 ± 1.66% and 96.13 ± 0.21% peptide depletion, respectively. These results confirmed the assay was valid. Because there was no peptide depletion by the test substance, no further analysis was performed to measure dimerized- or oxidized-peptide by the test substance.

 

Table 1: Individual data from free peptide quantitation and average peptide depletion

Group

Replicate#

Analyte Peak Area (counts)

Peptide conc. (mM)

Peptide depletion (%)

Average depletion (%)

Test substance

1

15300000

98.03

1.97

4.22 ± 1.84

2

15200000

97.37

2.63

3

14700000

94.07

5.93

4

14700000

94.07

5.93

5

14900000

95.39

4.61

Negative control

1

14600000

93.40

6.60

4.83 ± 1.66

2

14900000

95.39

4.61

3

15100000

96.71

3.29

Positive control

1

1030000

3.78

96.22

96.13 ± 0.21

2

1080000

4.11

95.89

3

1020000

3.71

96.29

Applicant's summary and conclusion

Interpretation of results:
other: Under the test conditions, there is no evidence that the test substance contains direct protein reactivity which would cause skin sensitisation.
Remarks:
Criteria used for interpretation of results: EU
Conclusions:
Under the test conditions, there is no evidence that the test substance contains direct protein reactivity which would cause skin sensitisation.
Executive summary:

The test system consists of a model peptide selected from an endogenous human protein expressed in skin tissue. The peptide consists of 7 amino acids and has an acetylated N-terminus. Sequence: Ac-NKKCDLF; Purity: 95.9% (HPLC-UV). The test substance was completely soluble in acetonitrile and was not precipitated by mixing with peptide solutions. After 24 h incubation, there was no colour change or a precipitate observed from the test substance. The test article did not have any UV absorbance at 220 nm through entire HPLC chromatography and therefore there was no interference with HPLC-UV analyses for peptides. Furthermore, the test substance did not interfere with the MS detections used in the test system that were monitoring higher than 700.0 m/z.

Using the established calibration curve, the concentrations of free peptide were calculated for each sample (Table 1). Average peptide depletion by the test substance was 4.22 ± 1.84%. Negative and positive controls resulted in 4.83 ± 1.66% and 96.13 ± 0.21% peptide depletion, respectively. These results confirmed the assay was valid. Because there was no peptide depletion by the test substance, no further analysis was performed to measure dimerized- or oxidized-peptide by the test substance.