6-METHOXYPYRIDINE-3-CARBALDEHYDE

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 September - 13 September, 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

6-methoxypyridine-3-carbaldehyde

Cas Number:

65873-72-5

Molecular formula:

C7H7NO2

IUPAC Name:

6-methoxypyridine-3-carbaldehyde

Test material form:

solid: particulate/powder

Details on test material:

Batch (Lot) Number: 2019-03-29
Physical Description: Cream powder
Storage Conditions: Kept in a controlled room temperature area, protected from light

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

other: human-derived epidermal keratinocytes

Cell source:

other: not specified

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

The test article was administered to the test system without dilution. Since the test article was a powder, 25 µL of CMF DPBS was applied to the tissues prior to addition of approximately 25 mg of the test article, which was administered using a dosing spoon. A sterile rod was used to spread the test article over the surface of the tissues.

Duration of treatment / exposure:

The test article, LSN2607535 (COM-1074), the positive control [5% Sodium Dodecyl Sulfate (SDS)], and the negative control [Calcium & Magnesium Free Dulbecco’s Phosphate Buffered Saline (CMF DPBS)] were treated in triplicate EpiDermTM tissues for a 60 ± 1 minute exposure period.

Duration of post-treatment incubation (if applicable):

There was a 42 ± 2 hour post-exposure incubation period.

Number of replicates:

triplicate

Test system

Details on study design:

Since the test article was a powder, a mesh was not used for its application onto the EpiDerm™ tissues.
The test article, LSN2607535 (COM-1074) was not observed to directly reduce MTT in the absence of viable cells.
The test article, LSN2607535 (COM-1074) was not considered to have probable photometric MTT interference.

The experimental design of the study consisted of the determination of the direct MTT reduction potential, assessment of colorant potential, a pH determinatin of the neat liquid test article and/or dosing dilution, and a definitive Skin Irritation Test (SIT). On the day of receipt, the EpiDerm(TM) tissues were conditioned by an overnight incubation for release of transport-stress related compounds and debris. After pre-incubation, tissues were topically exposed in triplicate to the test article, positive control, and negative control for 60 minutes. Tissues were then thoroughly rinsed to remove the test or control article, blotted, and transferred to fresh medium. After a 24-hour incubation period, the tissues were re-fed with fresh medium, and incubated for another 18 hours for a total 42-hour post-exposure incubation period. Viability was determined by the NAD(P)H-dependent microsomal enzyme reduction of MTT in control and test article-treated tissues. The MTT assay was performed by transferring the tissues to 24-well plates containing MTT. After a 3 hour MTT incubation, the blue formazan salt formed by cellular mitochonria was extracted with 2 mL isopropanol per tissue and the optical denisty of the extracted formazan was determined with a spectrophotometer at 570 nm. Relative cell viability was calculated for each tissue as % of the mean of the negative control-treated tissues. Skin irritation potential of the test article was predicted if the relative viability was less than or equal to 50%.

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Value:

31

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Other effects / acceptance of results:

The mean tissue viability of the positive control was 5%.

Any other information on results incl. tables

The assay was accepted when the following criteria were met: 1) the positive control (5% SDS) resulted in a mean tissue viability  ≤ 20%, 2) the mean OD₅₇₀ value of the negative control tissues was >/= 0.8 and < 2.8, and 3) the standard deviations of the positive and negative control calculated from individual percent tissue viabilities of the three identically treated replicates were < 18%.

Applicant's summary and conclusion

Interpretation of results:

other: Self-classified as category 2

Conclusions:

According to the prediction model presented in OECD TG 439, the test article was predicted to be an irritant. Additional testing would be needed to determine if the test article was a GHS Category 1 (Severe/Corrosive) or GHS Category 2 (Irritant) for skin irritation.