2-[4-(4-Alkoxyphenyl)-(pyridin-2-yl)-heteromonocyclyl]phenol

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study initiation date - 11 January 2021; Experiment start date - 18 January 2021; Experiment completion date - 22 January 2021; Study completion date - 05 March 2021.

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Test Item: FAT 75637/B TE
Physical Appearance: Light yellow powder
Purity: 99.4 % all organic constituents; 95.0 % main constituent
Batch No: AT-0063765400
Manufactured Date: 21st April 2020
Expiry Date: May 27th, 2025

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

foreskin from multiple donors

Justification for test system used:

The assessment of skin irritation has typically involved the use of laboratory animals (OECD TG 404). In relation to animal welfare concerns, TG 404 recommends the use of a tiered testing strategy for the determination of skin corrosion and irritation which includes the use of validated in vitro or ex vivo test methods avoiding pain and suffering of animals.

One of the validated in vitro test methods adopted by the OECD TG 439 makes use of reconstructed human epidermis (RhE) which closely mimics the biochemical and physiological properties of the upper parts of the human skin, i.e. the epidermis.

Vehicle:

unchanged (no vehicle)

Details on test system:

EpiSkin kit
EpiSkin is an in vitro reconstructed human epidermis (RHE) from normal human keratinocytes cultured on a collagen matrix at the air liquid interface. This is a three-dimensional human skin model comprising a reconstructed epidermis with a functional stratum corneum. Differentiated and stratified epidermis model comprises the main basal, supra basal, spinous and granular layers and a functional stratum corneum containing intercellular lamellar lipid layers representing main lipid classes analogous to those found in vivo.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

10 mg

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

42 hours ± 1

Number of replicates:

3

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

15 minutes exposure

Value:

72.03

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

Preliminary Tests for Coloring and Direct MTT Reduction Potential of the Test Item: In the coloring potential test, the resultant solution was not colored, hence, it was concluded that the test item does not have the intrinsic ability to become colored when it interacts with water. In the direct MTT reduction potential test, the color of MTT solution did not turn to either blue or purple, hence, it was concluded that the test item did not interact with MTT. Similarly, the water control tested did not show any coloring potential nor did it reduce the MTT.

Skin Irritation Test
The results show the mean tissue viability obtained after 15 minutes treatment with the test item compared to the negative control tissues. Skin irritation is expressed as the ability of the test item to reduce the cell viability after exposure to the test items. The relative mean tissue viability obtained after 15 minutes treatment with the test item compared to the negative control tissues was 72.03 %. The positive control had a mean cell viability of 4.74 % after 15 minutes exposure. The absolute mean OD570 of the negative control tissues was within the laboratory historical control data range.

Any other information on results incl. tables

Individual Tissue Viability of Epidermis Units (Relative)

	% Individual Viability
	R1	R2	R3	Mean	SD
Positive control	4.58	4.69	4.96	4.74	0.20
Test Item	66.63	74.00	75.46	72.03	4.73

SD: Standard Deviation Negative control mean: 0.9283

R1, R2 & R3: triplicate exposures

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The mean relative tissue viability for the test item was 72.03 %. Hence, the test item is predicted to be non-irritant under the experimental conditions described in this report.

Executive summary:

The test item, FAT 75637/B was tested for its possible skin irritation potential using a three-dimensional Reconstructed Human Epidermis model, EpiSkin, through topical application for 15 minutes. This study was conducted according to OECD test guideline 439 in a GLP-certified laboratory. The test item is a solid and was applied directly to the top of the skin tissues at 10 mg/tissue and exposed for 15 minutes. Ten microliters (10 µL) of PBS and 10 µL of 5 % aqueous SDS were used as the negative and positive controls, respectively. After 41-hour post-incubation period, irritation potentials of FAT 75637/B TE were evaluated by assessing the cytotoxic (irritancy) effect. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the treatment. Skin irritation is expressed as the ability of the test item to reduce the cell viability after exposure to the test item. The relative mean tissue viability obtained after 15 minutes treatment with the test item was compared to the negative control tissues. The absolute mean OD570(optical density at 570 nm) of the negative control tissues was 0.9838. The positive control had a mean cell viability of 4.74 % after 15 minutes exposure, indicating that the test system functioned properly. The study indicated that the test item FAT 75637/B is predicted to be non- irritant in this in vitro skin irritation test as the percent viability is 72.03 % using reconstructed human epidermis under the conditions of testing employed.