Propyl 3,4,5-trihydroxybenzoate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Comparison of the Local Lymph Node Assay wit hthe Guinea-Pig Maximization Test for the Detection of a Range of Contact Allergens

Author:

Basketter D. A. and Scholes E. W.

Year:

1992

Bibliographic source:

Food Chem Toxicol 30:65-69

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

GLP compliance:

no

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Propyl 3,4,5-trihydroxybenzoate

EC Number:

204-498-2

EC Name:

Propyl 3,4,5-trihydroxybenzoate

Cas Number:

121-79-9

Molecular formula:

C10H12O5

IUPAC Name:

propyl 3,4,5-trihydroxybenzoate

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Aldrich Chemical Co. (Gillingham, Dorset, UK)

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8-12 weeks
- Animals of both sexes were used, but single experiments were limited to one sex.

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

5%, 10%, 25%

No. of animals per dose:

4

Details on study design:

MAIN STUDY
Groups of 4 mice were treated by a daily topical application of 25 µL of each concentration on the dorsal surface of each ear for 3 consecutive days. Control mice were treated with the vehicle alone. Five days after the first topical application, all mice were injected intravenously through the tail vein with 250 µL phosphate buffered saline (PBS) containing [3H]methyl thymidine (3HTdR; 20 µCi). After 5 hr the mice were killed by carbon dioxide asphyxiation, and the draining auricular lymph nodes were excised and pooled for each experimental group. A single-cell suspension of lymph node cells (LNC) was prepared by gentle mechanical disaggregation through a stainless-steel gauze (200-mesh size), using the plunger of a syringe. Pooled LNC were pelleted at 190g for 10 min, washed twice with 10 mL PBS and resuspended in 3 mL trichloroacetic acid (TCA; 5%) for the precipitation of macromolecules. After an overnight incubation with TCA at 4 °C, the precipitate was recovered by centrifugation, resuspended in 1 mL TCA and transferred to 10mL scintillation fluid. 3HTdR incorporation was measured by beta-scintillation counting. The proliferative response of LNC was expressed as radioactive disintegrations per min per lymph node (dpm/node), and as the ratio of 3HTdR incorporation into LNC of test nodes relative to that recorded for control nodes (test/control ratio).

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local lymph node assay
- Criteria used to consider a positive response: A chemical was regarded as a sensitiser in the LLNA if at least one concentration of the chemical resulted in a three-fold or greater increase in 3HTdR incorporation compared with control values. Also, the data had to be compatible with a biological dose response although an allowance was made, especially at high doses, for either local toxicity or immunological suppression.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

eugenol (CAS No 97-53-0)

mercaptobenzothiazole (CAS No 149-30-4)

Statistics:

N/A

Results and discussion

Positive control results:

Cinnamic aldehyde, eugenol and mercaptobenzothiazole were all classified as positive in this assay.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

>= 22.3

Test group / Remarks:

Concentration of 5%

Results 2

Key result

Parameter:

SI

Value:

>= 18.3

Test group / Remarks:

Concentration of 10%

Results 3

Key result

Parameter:

SI

Value:

>= 33.6

Test group / Remarks:

Concentration of 25%

Cellular proliferation data / Observations:

DETAILS ON STIMULATION INDEX CALCULATION : Described in the study as "ratio of test to control lymphocyte proliferation (dpm/node)"

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

Using the local lymph node assay technique with [3H]thymidine, propyl gallate at all tested concentrations (5%, 10% and 25%) yielded a positive response (elicited more than a 3-fold increase in isotope incorporation in lymphocytes relative to vehicle controls). Propyl gallate is classified as a skin sensitiser under the conditions of this assay.

Executive summary:

Using the local lymph node assay technique with [3H]thymidine in CBA/Ca mice, propyl gallate at all tested concentrations (5%, 10% and 25%) yielded a positive response (elicited more than a 3-fold increase in isotope incorporation in lymphocytes relative to vehicle controls). Propyl gallate is classified as a skin sensitiser under the conditions of this assay.