5-propyloxan-2-one

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

4 April to 5 May, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well conducted and well described study in accordance with GLP and OECD Guideline 471 without any deviation.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

21 July 1997.

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Version / remarks:

Directive 2000/32/EC.

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

Inspected on 2004-12-16 / Signed on 2005-03-11.

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

(5R)-5-propyloxan-2-one

Molecular formula:

C8 H14 O2

IUPAC Name:

(5R)-5-propyloxan-2-one

Constituent 2

Reference substance name:

(5S)-5-propyloxan-2-one

Molecular formula:

C8 H14 O2

IUPAC Name:

(5S)-5-propyloxan-2-one

Test material form:

liquid

Details on test material:

- Physical state: Colourless liquid
- Storage condition of test material: Room temperature

Method

Target gene:

Salmonella typhimurium histidine (his) reversion system and the Escherichia coli tryptophan (trp) reversion system

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Details on mammalian cell type (if applicable):

not applicable

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

10 % v/v S9; S9 fraction was prepared from liver homogenates of Sprague Dawley rat induced with Aroclor 1254

Test concentrations with justification for top dose:

Assay No. 1 (plate incorporation method):
30, 90, 300, 900 and 3000 μg/plate, with or without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 (uvr A-)
Assay No. 2 (pre-incubation method):
30, 90, 300, 900 and 3000 μg/plate, with or without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 (uvr A-)

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Ethanol
- Test substance preparation:
For the first bacteriostatic activity control, the highest dose studied is 5000 μg/plate. A solution at 200 mg/mL is prepared with ethanol.
For the two other bacteriostatic activity controls and mutagenic assays, the highest dose studied is 3000 μg/plate. A solution at 120 mg/mL is prepared with ethanol.

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Ethanol

True negative controls:

yes

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: cis-Platinum (II) Diammine Dichloride

Remarks:

without metabolic activation

Controls 2

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Ethanol

True negative controls:

yes

Positive controls:

yes

Positive control substance:

other:

Remarks:

with metabolic activation

Details on test system and experimental conditions:

SOURCE OF TEST SYSTEM: Strains of Salmonella typhimurium and Escherichia coli are obtained from "Unité de Programmation Moléculaire et Toxicologie Génétique" (CNRS UA 144) (Institut Pasteur).

METHOD OF APPLICATION: in medium; in agar (plate incorporation); preincubation

DURATION
- Preincubation period: Pre-incubation assay where the test substance was preincubated with the test strain, and 500 μL of S9-mix fraction for 1 hour at 37° C prior to mixing with the overlay agar and pouring onto the surface of the minimal agar plate.
- Exposure duration: Plates were incubated at 37 °C over a 48 hour period

NUMBER OF REPLICATIONS: 3 plates/dose for all groups

DETERMINATION OF CYTOTOXICITY
- Method: reduced number of spontaneous reversions indicating the bacteriostatic activity.

- OTHER:
- Checking strains: The genotype of bacterial strains was checked for Histidine and tryptophan requirements; Loss of cell wall LPS (rfa mutation) measuring crystal violet inhibition for Salmonella typhimurium strains; Ampicillin resistance for the strains which have the pKM 101 plasmide; Δuvr B mutation i.e. U.V.B sensitivity for Salmonella typhimurium and Δuvr A mutation i.e. U.V.A sensitivity for Escherichia coli; Spontaneous revertant rate
- After a 48 hour incubation period at 37° C, revertant colonies per plate are counted (n = 3).
- Sterility tests: The highest concentration and dilutions of the test substance (100 μL) were tested for sterility.
- Data were presented as the number of revertant colonies (mean ± standard deviation) per plate. The following ratio was calculated: R = Number of revertant colonies in the presence of the product / Number of revertant colonies in the absence of the product.

Rationale for test conditions:

Tested up to cytotoxicity limit.

Evaluation criteria:

The result of the test is considered as negative if the revertant number is below three fold the number of spontaneous reversions, for TA 1535 and TA 1537 strains, and below two fold the number of spontaneous reversions for TA 98, TA 100 and Escherichia coli WP2(uvrA-) (pKM 101) strains with and/or without metabolic activation.
The validity criteria are as follows :
- bacteriostatic activity of the highest concentration shall be equal to or less than 75 %, - the spontaneous reversion rate of the absolute negative control shall comply with the laboratory’s historical control data.
- the mean number of revertant colonies obtained for each strain and the corresponding positive control, with and/or without metabolic activation shall comply with laboratory’s historical control data.
The result of the test is considered positive if a concentration – related increase is obtained in one, or several of the 5 strains, with and/or without metabolic activation; a mutagenic effect is taken into account for a given concentration of the test substance if the number of revertant colonies is at least two fold that of spontaneous revertant colonies number for TA 98, TA 100 and Escherichia coli WP2(uvrA-) (pKM 101), and three fold for TA 1535 and TA 1537.
All results must be confirmed in an independent experiment.

Statistics:

None

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium, other: TA 1535, TA 1537, TA 98, TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

BACTERIOSTATIC ACTIVITY CONTROL (STRAIN TA 100)
Bacteriostatic activity control (strain TA 100): In the first control, an important bacteriostatic activity of 94 % is observed in the presence of the test substance at 5000 μg/plate. The test substance is used at the following doses 3000, 900, 300, 90 and 30 μg/plate for bacteriostatic activity control 2 and 3. Then a bacteriostatic activity of 72 % compatible with the maximum level acceptable 75 % is observed, in the presence of the test substance at 3000 μg/plate.
The test substance is tested at the following doses: 3000, 900, 300, 90 and 30 μg/plate.

HISTORICAL CONTROL DATA
- See historical control table in "Attached background material" section

MUTAGENICITY RESULTS
- There is no significant difference between the number of spontaneous reversions, the number of reversions obtained in the positive controls (without and with metabolic activation), and the mean of corresponding experimental historic values obtained in the laboratory. There is no evidence of any increase in the number of revertant colonies in the presence of the test substance (3000, 900, 300, 90 and 30 μg) without and with metabolic activation for bacterial strains in Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and Escherichia coli WP2(uvrA-) (pKM 101).
- Results were confirmed in a second independent experiment.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- In the presence of the test substance at 3000 μg/plate we observe for some bacterial strains like Salmonella typhimurium TA 1535, TA 98 and Escherichia coli WP2(uvrA-) (pKM 101) a significant decrease of the number of spontaneous reversions without or with metabolic activation which confirmed the bacteriostatic activity observed at this dose.

OTHERS:
Sterility test did not show any bacterial growth in presence of all substance doses / S9 mix.
Genotoxicity testing: see tables 3.1 to 3.4 for TA 1535; 4.1 to 4.4 for TA 1537; 5.1 to 5.4 for TA 98; 6.1 to 6.4 for TA 100; 7.1 to 7.4 for Escherichia coli in "Attached background material" section.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:

Under the test conditions, test substance is not considered as mutagenic with and without metabolic activation in S. typhimurium (TA 1535, TA 1537, TA 98 and TA 100) and E. coli (WP2uvrA) strains.

Executive summary:

In a reverse gene mutation assay in bacteria, performed according to the OECD Guideline 471 and in compliance with GLP, strains of Salmonella typhimurium (TA 1535, TA 1537, TA 98 and TA 100) and Escherichia coli (WP2uvrA) were exposed to test substance at the following concentrations. 

Assay No. 1 (plate incorporation method): 30, 90, 300, 900 and 3000 μg/plate, with or without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 (uvr A-)

Assay No. 2 (pre-incubation method): 30, 90, 300, 900 and 3000 μg/plate, with or without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 (uvr A-) 

 

Metabolic activation system used in this test was10 % (v/v) S9 mix; S9 fraction prepared from liver homogenates of rats induced with Aroclor 1254. Negative, vehicle and positive control groups were also included in mutagenicity tests.

 

There is no significant difference between the number of spontaneous reversions, the number of reversions obtained in the positive controls (without and with metabolic activation), and the mean of corresponding experimental historic values obtained in the laboratory.

There is no evidence of any increase in the number of revertant colonies in the presence of the test substance (3 000, 900, 300, 90 and 30 μg) without and with metabolic activation for bacterial strains in Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and Escherichia coli WP2(uvrA-) (pKM 101).

In the presence of the test substance at 3 000 μg/plate we observe for some bacterial strains like Salmonella typhimurium TA 1535, TA 98 and Escherichia coli WP2(uvrA-) (pKM 101) a significant decrease of the number of spontaneous reversions without or with metabolic activation which confirmed the bacteriostatic activity observed at this dose. Results were confirmed in a second independent experiment.

 

Under the test conditions, test substance is not considered as mutagenic with and without metabolic activation in these bacterial systems.

This study is considered as acceptable and satisfies the requirement for reverse gene mutation endpoint.