Concrete of Cistus ladaniferus (Cistaceae) obtained from stems and leaves by organic solvents extraction

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 18 to 23, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

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)

Version / remarks:

The procedure followed is based on the recommended EpiSkin™ SOP, Version 1.8 (February
2009), ECVAM Skin Irritation Validation Study.

Deviations:

not applicable

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

not specified

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

UK GLP Compliance Program (inspected on March 12 to 14, 2014 / Signed on May 12, 2014)

Test material

Test material information

Constituent 1

Reference substance name:

Concrete of Cistus ladaniferus (Cistaceae) obtained from stems and leaves by organic solvents extraction

EC Number:

947-090-6

Molecular formula:

not applicable for UVCB

IUPAC Name:

Concrete of Cistus ladaniferus (Cistaceae) obtained from stems and leaves by organic solvents extraction

Test material form:

solid

Details on test material:

- Name of test material (as cited in study report): CISTUS CONCRETE
- Physical state: Dark brown solid at room temperature
- CAS No.: 89997-74-0
- EINECS-No.: 289-711-7
- Analytical purity: 100%UVCB
- Lot/batch No.: 14822 (réf. 101412)
- Production date: 13 May 2013
- Date of Receipt: 11 February 2014
- Expiration date of the lot/batch: 13 May 2015
- Composition: Paraffins, labdanolic derivated
- Storage condition of test material: Room temperature 20 ± 5 °C, keep away from light and humidity

In vitro test system

Test system:

human skin model

Source species:

other: EPISKIN™ Reconstructed Human Epidermis Model Kit

Cell type:

non-transformed keratinocytes

Cell source:

other: reconstructed epidermises

Details on animal used as source of test system:

Not relevant

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE:
Supplier: SkinEthic Laboratories, Lyon, France
Date received: 17 February 2015
Expiry date: 23 February 2015
EpiSkinTM Tissues (0.38cm2) lot number: 15-EKIN-007
Maintenance Medium lot number: 15-MAIN3-007
Assay Medium lot number: 15-ESSC-007

MAIN TEST:
Application of Test Item and Rinsing (Day 1): 2 mL of maintenance medium, warmed to approximately 37 °C, was pipetted into the second column of 3 wells of the 12 well plate. The test item was applied topically to the corresponding tissues ensuring uniform covering. 5 μL of sterile distilled water was topically applied to the epidermal surface in order to moisten the tissue culture surface to assist test item removal (see discussion). 10 µL (26.3 mg/cm2) of the test item was then applied to the epidermal surface. .

REMOVAL OF TEST SUBSTANCE
- Washing: At the end of the exposure period, each tissue was removed from the well using forceps. For the test item treated tissues the test item was peeled off the tissue culture surface using a pair of sterile forceps prior to rinsing. The tissues were rinsed using a wash bottle containing DPBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approximately 40 seconds using a constant soft stream of DPBS to gently remove any residual test item. The rinsed tissues were transferred to the second column of 3 wells containing 2 mL of maintenance medium in each well. The rinsed tissues were incubated at 37 oC, 5% CO2 in air for 42 hours.

MTT LOADING/FORMAZAN EXTRACTION (Day 3)
Following the 42-Hour post-exposure incubation period each 12-well plate was placed onto a plate shaker for 15 minutes to homogenize the released mediators in the maintenance medium. 1.6 mL of the maintenance medium from beneath each tissue was transferred to pre-labeled micro tubes and stored in a freezer at -14 to -30 ºC for possible inflammatory mediator determination.
2 mL of a 0.3 mg/mL MTT solution, freshly prepared in assay medium, was pipetted into the third column of 3 wells of the 12-well plate(s). The tissues were transferred to the MTT filled wells, being careful to remove any excess maintenance medium from the bottom of the tissue insert by blotting on absorbent paper. The tissues were incubated for 3 hours at 37 °C, 5% CO2 in air. At the end of the 3-Hour incubation period each tissue was placed onto absorbent paper to dry. A total biopsy of the epidermis was made using the EPISKINTM biopsy punch. The epidermis was carefully separated from the collagen matrix using forceps and both parts (epidermis and collagen matrix) placed into labeled 1.5 mL micro tubes containing 500 μL of acidified isopropanol, ensuring that both the epidermis and collagen matrix were fully immersed. Each tube was plugged to prevent evaporation and mixed thoroughly on a vortex mixer. The tubes were refrigerated at 1 to 10 °C until Day 6 of the experiment, allowing the extraction of formazan crystals out of the MTT-loaded tissues.

ABSORBANCE/ OPTICAL DENSITY MEASUREMENTS (Day 6):
At the end of the formazan extraction period each tube was mixed thoroughly on a vortex mixer to produce a homogenous colored solution.
For each tissue, duplicate 200 μL samples were transferred to the appropriate wells of a pre-labeled 96-well plate. 200 μL of acidified isopropanol alone was added to the two wells designated as ‘blanks’. The optical density was measured (quantitative viability analysis) at 562 nm (without a reference filter) using the Anthos 2001 microplate reader.

VIABILITY CALCULATION:
- Data from individual replicate tissues (OD values and calculated percent tissue viability data for the test item and controls), mean percent tissue viability and standard deviation for each individual test item and control were reported in Table 7.3.1/1. The results were expressed as a viability percentage compared with the negative control: viability % = (mean OD test item / mean OD negative control) * 100

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- The test item was warmed to 70 °C to soften and then allowed to cool to 37 °C before use.
- Amount(s) applied (volume or weight with unit): 10 µL
- Concentration (if solution): Undiluted

The Test Item was a solid block and extremely sticky when at the using temperature of 37oC.
Test Item left adhered to the tissues would have been expected to have resulted in interference with the Optical Density measurements rendering the results unusable.
It was therefore considered that moistening the tissue culture surface with 5 μL of sterile water prior to application of the Test Item (as the method for application of solids) would increase the chance of adequate removal at the end of the exposure period without compromising the validity of the study.
At the end of the exposure period (rinsing) the Test Item was still required to be peeled off the tissue culture surface but not stuck fast (unable to remove). The fact that the Test Item need to be peeled away was considered to be evidence that adequate contact was achieved and the validity of the study was not compromised.

Duration of treatment / exposure:

15 minutes
At the end of the exposure period, tissues were rinsed and incubated at 37 °C, 5% CO2 in air for 42 h.

Duration of post-treatment incubation (if applicable):

42 hours post-exposure period

Number of replicates:

3

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean

Value:

105.9

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Direct MTT Reduction

The MTT solution containing the test item did not turn blue which indicated that the test item did not directly reduce MTT.

 

Table 7.3.1/1: Mean OD₅₆₂ Values and Percentage Viabilities for the Negative Control Item, Positive Control Item and Test Item

 

Item	OD562 of tissues	Mean OD562 of triplicate tissues	±SD of OD562	Relative individual tissue viability (%)	Relative mean viability (%)	± SD of Relative mean viability (%)
Negative Control Item	0.967	0.929	0.03	104.1	100*	3.5
	0.912			98.2
	0.909			97.8
Positive Control Item	0.063	0.065	0.02	6.8	7.0	1.7
	0.050			5.4
	0.082			8.8
Test Item	1.089	0.984	0.12	117.2	105.9	13.2
	0.849			91.4
	1.013			109.0

 

SD=Standard deviation; *= The mean viability of the negative control tissues is set at 100%; OD₅₆₂= Optical Density

 

Quality Criteria

The relative mean tissue viability for the positive control treated tissues was 7.0% relative to the negative control treated tissues and the standard deviation value of the percentage viability was 1.7%. The positive control acceptance criterion was therefore satisfied.

The mean OD562 for the negative control treated tissues was 0.929 and the standard deviation value of the percentage viability was 3.5%. The negative control acceptance criterion was therefore satisfied.

The standard deviation calculated from individual percentage tissue viabilities of the three identically test item treated tissues was 13.2%. The test item acceptance criterion was therefore satisfied.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the test conditions, test material is not classified according to Regulation (EC) No. 1272/2008 (CLP) and to the GHS.

Executive summary:

An in vitro skin irritation study was performed according to the OECD Guideline 439 and in compliance with GLP, using the EPISKIN^TM reconstructed human epidermis model.

Triplicate tissues were treated with the test item for an exposure period of 15 minutes. At the end of the exposure period each tissue was rinsed before incubating for 42 hours. At the end of the post-exposure incubation period each tissue was taken for MTT-loading. The maintenance medium from beneath each tissue was transferred to pre-labeled micro tubes and stored in a freezer for possible inflammatory mediator determination. After MTT-loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues. At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 μL samples were transferred to the appropriate wells of a pre-labeled 96-well plate. The optical density was measured at 562 nm. Data are presented in the form of percentage viability (MTT reduction in the test item treated tissues relative to negative control tissues).

 

The relative mean viability of the test item treated tissues was 105.9% after the 15-Minute exposure period and 42 hours post-exposure incubation period. The quality criteria required for acceptance of results in the test were satisfied.

 

Under the test conditions, test material is not classified according to Regulation (EC) No. 1272/2008 (CLP) and to the GHS.

This study is considered as acceptable and satisfies the requirement for skin irritation endpoint.