1-methyl-3-((methyl-λ2-azanyl)methyl)-1H-pyrazole-5-carbonitrile hydrochloride

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:

14 March 2016 to 31 March 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

Organisation for Economic Co-operation and Development (OECD), OECD Guidelines for Testing of Chemicals; Guideline no. 471: "Genetic Toxicology: Bacterial Reverse Mutation Test" (Adopted July 21, 1997).

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

European Community (EC). Commission regulation (EC) No. 440/2008, Part B: Methods for the Determination of Toxicity and other health effects, Guideline B.13/14: "Mutagenicity: Reverse Mutation Test using Bacteria”. Official Journal of the European Union No. L142, 31 May 2008.

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

1-methyl-3-[(methylamino)methyl]-1H-pyrazole-5-carbonitrile hydrochloride

EC Number:

943-430-2

Cas Number:

1643141-20-1

Molecular formula:

C7H10N4Cl

IUPAC Name:

1-methyl-3-[(methylamino)methyl]-1H-pyrazole-5-carbonitrile hydrochloride

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Purity (by HPLC @ 225 nm) 100.0 % [a/a]

Method

Target gene:

histidine

Species / strain

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

Rat liver microsomal enzymes (S9 homogenate) were obtained from Trinova Biochem GmbH, Giessen, Germany and were prepared from male Sprague Dawley rats that had been injected intraperitoneally with Aroclor 1254 (500 mg/kg body weight).
Each S9 batch is characterised with the mutagens benzo-(a)-pyrene and 2-aminoanthracene, which require metabolic activation, in tester strain TA100 at concentrations of 5 μg/plate and 2.5 μg/plate, respectively.

Test concentrations with justification for top dose:

Eight concentrations, 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 μg/plate were tested in triplicate.

Selection of an adequate range of doses was based on a dose range finding test with the strains TA100 and WP2uvrA, both with and without 5% (v/v) S9-mix.

Vehicle / solvent:

Water

Controls

Untreated negative controls:

yes

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

2-nitrofluorene

sodium azide

methylmethanesulfonate

other: ICR-191 and 2-aminoanthracene

Remarks:

2-aminoanthracene used with metabolic activation, everything else is without

Details on test system and experimental conditions:

6.5. Test system
Test system Salmonella typhimurium bacteria and Escherichia coli bacteria
Rationale Recommended test system in international guidelines (e.g. OECD, EC).
Source Trinova Biochem GmbH, Germany [Master culture from Dr. Bruce N. Ames
(TA1535: 2006, TA1537: 2009, TA98: 2015, TA100: 2015; and Master culture
from The National Collections of Industrial and Marine Bacteria, Aberdeen, UK
(WP2uvrA: 2008)]
The characteristics of the different Salmonella typhimurium strains were as follows:
Strain Histidine mutation Mutation type
TA1537 hisC3076 Frameshift
TA98 hisD3052/R-factor* Frameshift
TA1535 hisG46 Base-pair substitutions
TA100 his G46/R-factor* Base-pair substitutions
*: R-factor = plasmid pKM101 (increases error-prone DNA repair)

Each tester strain contained the following additional mutations:
rfa : deep rough (defective lipopolysaccharide cellcoat)
gal : mutation in the galactose metabolism
chl : mutation in nitrate reductase
bio : defective biotin synthesis
uvrB : loss of the excision repair system (deletion of the ultraviolet-repair B gene)

The Salmonella typhimurium strains are regularly checked to confirm their histidine-requirement, crystal violet sensitivity, ampicillin resistance (TA98 and TA100), UV-sensitivity and the number of spontaneous revertants.

The Escherichia coli WP2uvrA strain detects base-pair substitutions. The strain lacks an excision repair system and is sensitive to agents such as UV. The sensitivity of the strain to a wide variety of mutagens has been enhanced by permeabilization of the strain using Tris-EDTA treatment (Ref.1). The strain is regularly checked to confirm the tryptophan-requirement, UV-sensitivity and the number of spontaneous revertants.
Stock cultures of the five strains were stored in liquid nitrogen (-196°C).

Evaluation criteria:

No formal hypothesis testing was done. In addition to the criteria stated below, any increase in the total number of revertants should be
evaluated for its biological relevance including a comparison of the results with the historical control data range.

Statistics:

A test item is considered negative (not mutagenic) in the test if:

a) The total number of revertants in the tester strain TA100 or WP2uvrA is not greater than two (2) times the concurrent control, and the total number of revertants in tester strains TA1535, TA1537 or TA98 is not greater than three (3) times the concurrent vehicle control.

b) The negative response should be reproducible in at least one follow-up experiment.

A test item is considered positive (mutagenic) in the test if:

a) The total number of revertants in the tester strain TA100 or WP2uvrA is greater than two (2) times the concurrent control, or the total number of revertants in tester strains TA1535, TA1537, TA98 is greater than three (3) times the concurrent vehicle control.

b) In case a follow up experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one follow up experiment.

Results and discussion

Test results

Species / strain:

other: as listed above

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Based on the results of this study it is concluded that PF-06478031-01 is not mutagenic in the
Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay.