Lithium naphthalene-2-carboxylate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 September 2008 and 04 September 2008.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: SkinEthic Reconstituted Human Corneal model

Deviations:

no

Principles of method if other than guideline:

The test is based on the hypothesis that irritant chemicals are able to penetrate the stratum corneum of the SkinEthic RHC model and are sufficiently cytotoxic to cause cell death in the underlying cell layers.

GLP compliance:

yes (incl. QA statement)

Remarks:

The work described was performed in compliance with UK GLP standards (Schedule 1, Good Laboratory Practice Regulations 1999 (SI 1999/3106 as amended by SI 2004/0994)).

Test material

Test material information

Constituent 1

Reference substance name:

Lithium naphthalene-2-carboxylate

EC Number:

700-040-5

Cas Number:

674347-28-5

Molecular formula:

C11 H7 Li O2

IUPAC Name:

Lithium naphthalene-2-carboxylate

Test animals / tissue source

Species:

other: The SkinEthic RHC model consists of transformed human keratinocytes

Strain:

other: The SkinEthic RHC model consists of transformed human keratinocytes of the cell line HCE

Details on test animals or tissues and environmental conditions:

TEST ANIMALS:Not applicable
- Tissue: The purpose of this study was to determine the eye irritation potential of the test material using the SkinEthic Reconstituted Human Corneal model (HCE, SkinEthic Laboratories, Nice, France).
The SkinEthic RHC model consists of transformed human keratinocytes of the cell line HCE (LSU EYE Center, New Orleans, USA) that form a corneal epithelial tissue (mucosa), devoid of stratum corneum, resembling, histologically, the mucosa of the human eye.



ENVIRONMENTAL CONDITIONS
- Temperature (°C): The tissues were incubated overnight at 37°C
- Humidity (%): Not available
- Air changes (per hr): Not available
- Photoperiod (hrs dark / hrs light):Not available


IN-LIFE DATES: Not applicable

Test system

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):30 mg of the test material
- Concentration (if solution): Not applicable


VEHICLE
- Amount(s) applied (volume or weight with unit): Not applicable
- Concentration (if solution):Not applicable
- Lot/batch no. (if required): Not applicable
- Purity:Not applicable

Duration of treatment / exposure:

Triplicate tissues were treated with 30 mg of the test material for 10 minutes.

Observation period (in vivo):

Not applicable

Number of animals or in vitro replicates:

Not applicable

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): At the end of the relevant exposure period, each tissue insert was removed from the well using forceps and rinsed using a wash bottle containing Dulbecco’s Phosphate Buffered Saline (DPBS). Rinsing was achieved by filling and emptying each tissue insert using a constant soft stream of DPBS to gently remove any residual test material. Excess DPBS was removed by blotting the bottom of the insert with absorbent paper. Each tissue was placed into a pre-labelled 24 well plate designated ‘holding plate’ containing 300 µl of maintenance medium (at room temperature) until all the tissues were rinsed
- Time after start of exposure: 10 minutes


SCORING SYSTEM: At the end of the incubation period, the tissues were visually examined and the degree of MTT staining evaluated (qualitative evaluation of tissue viability). The inserts were blotted on absorbent paper to remove residual MTT solution and transferred to a pre labelled 24 well plate designated ‘MTT extraction plate’ containing 0.75 ml of Isopropanol in each of a sufficient number of wells. An extra 0.75 ml of Isopropanol was added onto each tissue and the plate sealed to prevent Isopropanol evaporation. The plate was wrapped in aluminium foil (to protect from light) and allowed to stand overnight at room temperature to extract the formazan crystals out of the tissue.
At the end of the extraction period, each tissue insert was pierced with a pipette fitted with a 1000 µl tip and the extraction solution forced vigorously up and down through the tissue insert until a homogeneous solution was obtained. The empty inserts were discarded. For each tissue triplicate 200 µl samples were transferred to the appropriate wells of a pre-labelled 96-well plate. 200 µl of Isopropanol alone was added to three wells designated as ‘blanks’. The optical density was measured (quantitative measurement of tissue viability) at 540nm (OD540) using the Anthos 2001 microplate reader.



TOOL USED TO ASSESS SCORE:
Relative Mean tissue viability
(% negative control) Prediction
Tissue viability <60 Irritant (I)
Tissue viability ≥60 Non-Irritant (NI)

Results and discussion

In vivo

Results

Irritation parameter:

overall irritation score

Remarks:

% viability

Basis:

mean

Time point:

other: 10 minutes

Score:

17.2

Max. score:

17.2

Reversibility:

not specified

Remarks on result:

other: The relative mean viability of the test material treated tissues after a 10 minute exposure was 17.2%.

Irritant / corrosive response data:

The relative mean viability of the test material treated tissues after a 10 minute exposure was 17.2%.

Other effects:

It was considered unnecessary to proceed with tissue histopathology.

Any other information on results incl. tables

Assessment of Direct Test Material Reduction of MTT

The test material was not able to directly reduce MTT.

Assessment of Eye Irritation Potential

The mean OD₅₄₀values and mean viabilities for each treatment group are given in Table 1.

The relative mean viability of the test material treated tissues after a 10 minute exposure was 17.2%.

It was considered unnecessary to proceed with tissue histopathology.

Qualitative Evaluation of Tissue Viability (MTT Uptake Visual Assessment)

The qualitative evaluation of tissue viability is presented in Table 2.

The test material treated tissues appeared white and therefore were considered to be indicative of dead tissue. The negative control treated tissues appeared blue and therefore were considered to be indicative of viable tissue. The positive control material treated tissues appeared blue/white and therefore were considered to be indicative of semi‑viable tissue.

Table1               Assessment of Eye Irritation Potential – Viability of RHC Tissues

Material	Mean Tissue Viability	Mean OD540	% Viability
Negative ControlÅ	0.955	0.917	100*
	0.878
Positive ControlÅ	0.212	0.249	27.2
	0.286
Test Material	0.173	0.158	17.2
	0.142

*=         The mean viability of the negative tissues is set at 100%

Table2               Qualitative Evaluation of Tissue Viability (MTT uptake visual evaluation)

Material	Score
	Tissue 1	Tissue 2
Negative ControlÅ	-	-
Positive ControlÅ	+	+
Test Material	++	++

MTT Visual Scoring Scheme of SkinEthic Tissues

-       =   Blue tissue (viable)

+      =   Blue/White tissue (semi viable)

++    =   Tissue completely white (dead)

 

Applicant's summary and conclusion

Interpretation of results:

irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

According to the protocol followed the test material was considered to be Irritant (I).

Executive summary:

Introduction. The purpose of this study was to determine the eye irritation potential of the test material using the SkinEthic Reconstituted Human Corneal model (HCE, SkinEthic Laboratories,,) after a treatment period of 10 minutes. The test is based on the hypothesis that irritant chemicals are able to penetrate the corneal epithelial tissue and are sufficiently cytotoxic to cause cell death.

Methods. The experimental design of the study consists of a test for Direct Reduction of MTT by the test material followed by the main test.

For the main test, triplicate SkinEthic tissues were treated with 30 mg of the test material for 10 minutes. Triplicate tissues treated with 30 µl of Solution A served as the negative control and triplicate tissues treated with 30 µl of 1% w/v Sodium Dodecyl Sulphate served as the positive control.

At the end of the exposure period each SkinEthic tissue was rinsed. The rinsed tissues (two per group) were taken for MTT loading. The remaining tissues were retained for possible histopathology. Following MTT loading the reduced MTT was extracted from the tissues.

After extraction the absorbency of triplicate aliquots of the extracted MTT solution for each SkinEthic tissue was measured (OD₅₄₀). Data are presented in the form of % viability (MTT conversion relative to negative controls).

The test material was classified according to the following criteria:

i)                   If the % relative mean tissue viability was ≥ 60% the test material was considered to be non‑irritant.

ii)                  If the % relative mean tissue viability was < 60% the test material was considered to be an irritant.

Results. The relative mean viability of the test material treated tissues after a 10 minute exposure was 17.2%.

It was considered unnecessary to proceed with tissue histopathology.

Quality criteria. The quality criteria required for acceptance of results in the test were satisfied.

Conclusion. According to the protocol followed the test material was considered to be Irritant (I).