L-Tyrosine, 3,5-dinitro-

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

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:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

L-Tyrosine, 3,5-dinitro-

Cas Number:

17360-11-1

Molecular formula:

C9H9N3O7

IUPAC Name:

L-Tyrosine, 3,5-dinitro-

Test material form:

solid

In vitro test system

Test system:

human skin model

Vehicle:

other: Dulbecco’s Phosphate Buffered Saline (DPBS buffer)

Details on test system:

The test system is a commercially available EpiDermTM-Kit, procured by MatTek.
The EpiDermTM tissue consists of human-derived epidermal keratinocytes which have been cultured to form a multi-layered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers representing main
lipid classes analogous to those found in vivo. The EpiDermTM tissues are cultured on spe-cially prepared cell culture inserts.

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

Test system

Amount / concentration applied:

Tissue Amount
1 26.2 mg
2 27.2 mg
3 26.9 mg

Details on study design:

One plate (3 tissues) was used as negative control; each tissue was treated with 30 µL DPBS buffer, a nylon mesh was added in order to ensure sufficient contact with the tissue surface.
One plate was used as positive control; each tissue was treated with 30 µL 5% SDS-solution, a nylon mesh was added in order to ensure sufficient contact with the tissue sur-face.
One plate was used for treatment with the test item:
The tissues were wetted with 25 µL DPBS buffer before applying the test item and spread-ing it to match the tissue size.

Tissues were dosed in 1-minute-intervals. After dosing the last tissue, all plates were transferred into the incubator for 35 minutes at 37 ± 1°C and 5.0 ± 0.5% CO2.
1 hour after the first application, the inserts were removed from the plates using sterile forceps and rinsed immediately in 1-minute-intervals.
After rinsing, each tissue was blotted with sterile cellulose tissue and then transferred into a new 6-well-plate with fresh assay medium (0.9 mL).
Then, the tissues were set in the incubator for 23 hours and 20 minutes at 37 ± 1°C and 5.0 ± 0.5% CO2.

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

tissue 1

Value:

70.4

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

tissue 2

Value:

80.5

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

tissue 3

Value:

69.8

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 4

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean value

Value:

73.5

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item L-Tyrosine, 3,5-dinitro- (wet product) is considered as non-irritant to skin.
After the treatment, the mean value of relative tissue viability was reduced to 73.5%. This value is above the threshold for skin irritation (50%).
The optical density of the negative control was well within the required acceptability criteri-on of 0.8 ≤ mean OD ≤ 2.8.
The positive control has met the acceptance criterion too, for thus ensuring the validity of the test system.
Variation within replicates was within the accepted range for negative control, positive con-trol and test item (required: ≤ 18%).
For these reasons, the result of the test is considered valid.

Executive summary:

Three tissues of the human skin model EpiDerm^TMwere treated with L-Tyrosine, 3,5-dinitro- (wet product) for 60 minutes.

The test item was applied directly to each tissue and spread to match the tissue size (0.63  cm²; as indicated by the supplier).

DPBS-buffer was used as negative control and 5% SDS solution was used as positive control.

After treatment with the negative control, the mean absorbance value was within the required acceptability criterion of 0.8 ≤ mean OD ≤ 2.8, OD was 1.5. The positive control showed clear irritating effects. The mean value of relative tissue viability was reduced to 2.8 % (required: ≤ 20%).

The variation within the tissue replicates of negative control, positive control and test item was acceptable (required: ≤ 18%).

 

After the treatment with the test item, the mean value of relative tissue viability was reduced to 73.5 %. This value is above the threshold for skin irritation potential (50%). Test items that induce values above the threshold of 50% are considered non- irritant to skin