Cholest-5-en-3-β-yl acetate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 January 2018 - 13 March 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Version / remarks:

09 October 2017

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Cholest-5-en-3-β-yl acetate

EC Number:

210-066-4

EC Name:

Cholest-5-en-3-β-yl acetate

Cas Number:

604-35-3

Molecular formula:

C29H48O2

IUPAC Name:

(1R,3aS,3bS,7S,9aR,9bS,11aR)-9a,11a-dimethyl-1-[(2R)-6-methylheptan-2-yl]-1H,2H,3H,3aH,3bH,4H,6H,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-7-yl acetate

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: White crystalline powder
- Storage condition: At room temperature

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): approx. 300 mg per cornea

Duration of treatment / exposure:

240 minutes

Details on study design:

SELECTION, PREPARATION AND QUALITY CHECK OF THE ISOLATED CORNEAS
The eyes were checked for unacceptable defects, such as opacity, scratches, pigmentation and neovascularization by removing them from the physiological saline and holding them in the light. Those exhibiting defects were discarded. The isolated corneas were stored in a petri dish with cMEM (Earle’s Minimum Essential Medium (Life Technologies, Bleiswijk, The Netherlands) containing 1% (v/v) L-glutamine (Life Technologies) and 1% (v/v) Fetal Bovine Serum (Life Technologies)). The isolated corneas were mounted in a corneal holder (one cornea per holder) of BASF (Ludwigshafen, Germany) with the endothelial side against the O-ring of the posterior half of the holder. The anterior half of the holder was positioned on top of the cornea and tightened with screws. The compartments of the corneal holder were filled with cMEM of 32 ± 1°C. The corneas were pre-incubated at 32 ± 1°C.
After the incubation period, the medium was removed from both compartments and replaced with fresh cMEM. Opacity determinations were performed on each of the corneas using an opacitometer (BASF-OP3.0, BASF, Ludwigshafen, Germany). The opacity of each cornea was read against a cMEM filled chamber, and the initial opacity reading thus determined was recorded. Corneas that had an initial opacity reading higher than 7 were not used.

NUMBER OF REPLICATES
Three corneas were selected at random for each treatment group.

NEGATIVE CONTROL USED
- Amount(s) applied (volume or weight with unit): 750 µL of physiological saline per cornea

POSITIVE CONTROL USED
Amount(s) applied (volume or weight with unit): 750 µL per cornea
Concentration (if solution): 20% (w/v) Imidazole

APPLICATION DOSE AND EXPOSURE TIME
240 ± 10 minutes at 32 ± 1°C

TREATMENT METHOD: closed chamber

REMOVAL OF TEST SUBSTANCE
- Washing: yes (with MEM with phenol red (Eagle’s Minimum Essential Medium, Invitrogen Corporation) and thereafter with cMEM)
- Time after start of exposure: 240 minutes

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity:
The opacity of a cornea was measured by the diminution of light passing through the cornea. The light was measured as illuminance (I = luminous flux per area, unit: lux) by a light meter. The change in opacity for each individual cornea (including the negative control) was calculated by subtracting the initial opacity reading from the final post-treatment reading. The corrected opacity for each treated cornea with the test item or positive control was calculated by subtracting the average change in opacity of the negative control corneas from the change in opacity of each test item or positive control treated cornea. The mean opacity value of each treatment group was calculated by averaging the corrected opacity values of the treated corneas for each treatment group.
- Corneal permeability:
After the incubation period, the medium in the posterior compartment of each holder was removed and placed into a sampling tube labelled according to holder number. 360 µL of the medium from each sampling tube was transferred to a 96-well plate. The optical density at 490 nm (OD490) of each sampling tube was measured in triplicate using a microplate reader (TECAN Infinite® M200 Pro Plate Reader). Any OD490 that was 1.500 or higher was diluted to bring the OD490 into the acceptable range (linearity up to OD490 of 1.500 was verified before the start of the experiment). OD490 values of less than 1.500 were used in the
permeability calculation.
The mean OD490 for each treatment was calculated using cMEM corrected OD490 values. If a dilution has been performed, the OD490 of each reading of the positive control and the test item was corrected for the mean negative control OD490 before the dilution factor was applied to the reading.

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)
The mean opacity and mean permeability values (OD490) were used for each treatment group to calculate an in vitro score:
In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value)
Additionally the opacity and permeability values were evaluated independently to determine whether the test item induced irritation through only one of the two endpoints.

DECISION CRITERIA:
A test substance that induces an IVIS ≤ 3 is not classified for eye irritancy (UN GHS: no category);
A test substance that induces an IVIS > 55 is defined as a corrosive or severe irritan (UN GHS: catgeory 1);
For a test substance that induces an IVIS >3 and ≤ 55, no prediction on irritant potency can be made.

ACCEPTABILITY CRITERIA
The assay is considered acceptable if:
- The positive control gives an in vitro irritancy score that falls within two standard deviations of the current historical mean.
- The negative control responses should result in opacity and permeability values that are less than the upper limits of the laboratory historical range.

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

in vitro irritation score

Run / experiment:

first experiment

Value:

1.9

Negative controls validity:

valid

Remarks:

In Vitro Score 0.4

Positive controls validity:

valid

Remarks:

In Vitro Score 144

Results 2

Irritation parameter:

in vitro irritation score

Run / experiment:

second experiment

Value:

-0.7

Negative controls validity:

valid

Remarks:

In Vitro Score 3.6

Positive controls validity:

valid

Remarks:

In Vitro Score 164

Other effects / acceptance of results:

OTHER EFFECTS:
The corneas were clear or slightly translucent after the 240 minutes of treatment with Cholesteryl acetate. No pH effect of the test item was observed on the rinsing medium.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The negative control responses for opacity and permeability were less than the upper limits of the laboratory historical range indicating that the negative control did not induce irritancy on the corneas.
- Acceptance criteria met for positive control: The mean in vitro irritancy score of the positive control (20% (w/v) Imidazole) was 144 and 164 in the first and second experiment, respectively and within two standard deviations of the current historical positive control mean

Any other information on results incl. tables

Summary of Opacity, Permeability and In Vitro Scores

First experiment

Treatment	Mean Opacity	Mean Permeability	Mean In vitro Irritation Score^1, 2
Negative control	0.1	0.021	0.4
Positive control	107	2.489	144
Cholesteryl acetate	-0.1	0.134	1.9

¹    Calculated using the negative control mean opacity and mean permeability values for the positive control and test item.

²    In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value).

Second experiment

Treatment	Mean Opacity	Mean Permeability	Mean In vitro Irritation Score^1, 2
Negative control	2.7	0.055	3.6
Positive control	131	2.161	164
Cholesteryl acetate	-0.8	0.007	-0.7

¹    Calculated using the negative control mean opacity and mean permeability values for the positive control and test item.

²    In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value).

Applicant's summary and conclusion

Interpretation of results:

other: Not classified.

Remarks:

According to Regulation (EC) 1272/2008 and its amendments.

Conclusions:

Based on the outcome of a Bovine Corneal Opacity and Permeability test (BCOP) performed according to OECD 437 guideline and GLP principles, it is concluded that Cholesteryl acetate is not irritant or corrosive for the eye.

Executive summary:

A Bovine Corneal Opacity and Permeability test (BCOP) was performed with Cholesteryl acetate according to OECD guideline 437 and GLP principles. Cholesteryl acetate was applied undiluted (approx. 300 mg per cornea, n=3). The mean in vitro irritancy score of the positive control (20% (w/v) Imidazole) was 144 and 164 in the first and second experiment, respectively. The negative control responses for opacity and permeability were less than the upper limits of the laboratory historical range indicating that the negative control did not induce irritancy on the corneas. It was therefore concluded that the test conditions were adequate and that the test system functioned properly. Cholesteryl acetate did not induce ocular irritation through opacity or permeability, resulting in a mean in vitro irritancy score over two experiments of 0.6 after 240 minutes of treatment. Since Cholesteryl acetate induced an IVIS ≤ 3, no classification is required for eye irritation or serious eye damage According to Regulation (EC) 1272/2008 and its amendments.