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Skin irritation / corrosion

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Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
05.07.2018 - 26.07.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The study was performed in compliance with the Principle of Good Laboratory Practice, confirmed by Statement of GLP Compliance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)
Principles of method if other than guideline:
None known.
GLP compliance:
yes (incl. QA statement)

Test material

1
Reference substance name:
Rhatany, Krameria triandra, ext.
EC Number:
283-919-1
EC Name:
Rhatany, Krameria triandra, ext.
Cas Number:
84775-95-1
Molecular formula:
not available
IUPAC Name:
Rhatany, Krameria triandra, ext.
Test material form:
liquid: viscous
Specific details on test material used for the study:
Name Krameria triandra extract obtained from Rhatany root by hydroalcoholic extraction
Batch no. PES180014
Appearance reddish brown viscous substance
Composition Krameria triandra extractobtained from Rhatany root by hydroalcoholic extraction
Purity not applicable, UVCB
Homogeneity inhomogeneous, warm up to about 60°C and stir
Expiry date Jan. 2019
Storage Fridge (2 - 8 °C)
CAS No. 84775-95-1
EINECS-No. 283-919-1
Stability in solvents H2O: 96h; EtOH: 96h; acetone: 96h; CH3CN: 96h; DMSO: 96h
Solubility H2O: unknown; EtOH: >1 g/L; acetone: >1 g/L; CH3CN: >1 g/L; DMSO: >1 g/L
Structural Formula not stated
SMILES Code not stated

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Details on animal used as source of 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 arranged in patterns analogous to those found in vivo. The EpiDermTM tissues are cultured on specially prepared cell cultures inserts.
Justification for test system used:
For the test system, provided by MatTek Corporation, a Certificate of Analysis is submitted which shows the quality controll data of the test system.
Vehicle:
other: Dulbecco’s Phosphate-Buffered Saline
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 arranged in patterns analogous to those found in vivo. The EpiDermTM tissues are cultured on specially prepared cell cultures inserts.
EpiDermTM tissues were procured from MatTek In Vitro Life Science Laboratories, Bratislava.
Designation of the kit: OCL-212-SCT
Day of delivery: 24. Jul. 2018
Batch: 28639
Control samples:
yes, concurrent negative control
yes, concurrent positive control

Test system

Duration of treatment / exposure:
3 minutes and 1 hour
Details on study design:
Demonstration of Proficiency:
The validity of the skin corrosion study at LAUS GmbH was demonstrated in a proficiency study. For this purpose, 12 proficiency chemicals (indicated by the OECD 431 guideline) were tested.
All of the 12 proficiency chemicals were correctly categorized. Therefore, the proficiency of the skin corrosion study was demonstrated.

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
other: Mean absorbance values (OD 570 nm)
Run / experiment:
Mean of 3 minutes experiments with two tissues
Value:
1.659
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of irritation
Other effects / acceptance of results:
The test item is considered non-corrosive to skin.
But as the test item Krameria triandra extract obtained from Rhatany root by hydroalcoholic extraction is inhomogeneous, a false negative result cannot be excluded.
After 3 minutes treatment, the mean value of relative tissue viability of the test item was increased to 104.3%. This value is well above the threshold for corrosivity (50%). After 1 hour treatment the mean value of relative tissue viability of the test item was reduced to 96.1%. This value is well above the threshold for corrosivity (15%).

The values of the negative control met the required acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for both treatment intervals, thus showing the quality of the tissues.
The positive control has met the validity criterion too, thus ensuring the validity of the test system.

For these reasons, the result of the test is considered valid.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Remarks:
The test item is considered non-corrosive to skin.
Conclusions:
The mean value of relative tissue viability of the test item was increased to 104.3% after 3 minutes treatment. This value is above the threshold for corrosivity (50%). After 1 hour treatment, the mean value of relative tissue viability of the test item was reduced to 96.1%, lying above the threshold for corrosivity (15%). Therefore, the test item is considered as non-corrosive to skin.
But as the test item Krameria triandra extract obtained from Rhatany root by hydroalcoholic extraction is inhomogeneous, a false negative result cannot be excluded.
Executive summary:

This study was performed in order to evaluate the skin corrosion potential of Krameria triandra extract obtained from Rhatany root by hydroalcoholic extractionto human skin in an in vitro study.

The skin corrosion test refers to the production of irreversible tissue damage following the application of a test material on a reconstructed human skin model. It allows the identification of corrosive chemical substances and mixtures.

The test item is applied topically to a three-dimensional human skin model, comprising of non-transformed, 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 principle of the human skin model assay is based on the hypothesis that corrosive chemicals are able to penetrate the stratum corneum by diffusion or erosion and are cytotoxic to the underlying cell layers.

Corrosive chemicals are identified by their ability to decrease cell viability. The viability is measured by enzymatic conversion of the vital dye MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) into a blue formazan salt, that is quantitatively measured after extraction from tissues.

One valid experiment was performed.

Two tissues of the human skin model EpiDermTMwere treated with the test itemfor 3 minutes and 1 hour, respectively. The test item was applied to each tissue and spread to match the tissue size.

Demineralised water was used as negative control and 8 M KOH was used as positive control.

After treatment, the respective substance was rinsed from the tissues. Then, cell viability of the tissues was evaluated by addition of MTT, which can be reduced to a blue formazan. Formazan production was evaluated by measuring the optical density (OD) of the resulting solution.

After treatment with the negative control, the absorbance values were within the required acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for both treatment intervals thus showing the quality of the tissues. The OD was 1.6 (3 minutes experiment) and 1.7 (1 hour experiment).

The positive control showed clear corrosive effects for both treatment intervals. The mean relative tissue viability value was reduced to 12.3 % for the 1 hour treatment.

After 3 minutes treatment with the test item, the mean value of relative tissue viability was increased to 104.3 %. This value is above the threshold for corrosion potential (50%). After 1  hour treatment, mean value of relative tissue viability was reduced to 96.1%. This value, too, is above the threshold for corrosion potential (15%).

Therefore, the test itemKrameria triandra extract obtained from Rhatany root by hydroalcoholic extractionis considered non-corrosive to skin in the Reconstructed Human Epidermis (RHE) Test Method.

But as the test itemKrameria triandra extract obtained from Rhatany root by hydroalcoholic extraction is inhomogeneous, a false negative result cannot be excluded.

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