2-Amino-3-bromopyridine

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:

Nov 2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Justification for type of information:

This study was a non-regulatory study for which a claim of GLP compliance was not made. However, the laboratory procedures were conducted in accordance with the current GLP requirements of the UK MHRA and OECD.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

3-bromopyridin-2-amine

EC Number:

629-620-5

Cas Number:

13534-99-1

Molecular formula:

C5 H5 Br N2

IUPAC Name:

3-bromopyridin-2-amine

Test material form:

solid

Method

Target gene:

TA98, TA100, TA1535, TA97a and TA102

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA98, TA100, TA1535, TA97a and TA102

Metabolic activation:

with and without

Metabolic activation system:

Liver S-9 mix from male rats, Aroclor 1254-pretreated. Per plate, 0.5 mL of 10% S-9 mix was added

Test concentrations with justification for top dose:

Concentrations tested:
- Experiment 1: 16, 50, 160, 500, 1600 and 5000 μg/plate (using all strains +/-S-9).
- Experiment 2: 500, 1000, 2000, 3000, 4000 and 5000 μg/plate (TA1535 +S-9 only).

Vehicle / solvent:

The test article was completely soluble in the aqueous assay system at all concentrations tested.

Controls

Untreated negative controls:

yes

Remarks:

Negative controls comprised treatments with the chosen vehicle

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

benzo(a)pyrene

mitomycin C

other: 2-aminoanthracene (AAN)

Details on test system and experimental conditions:

The objective of the Salmonella/microsome assay is to evaluate the mutagenic potential of a
test item by its effects on one or more histidine-requiring strains of Salmonella typhimurium in
the absence and presence of a liver metabolising system. The Ames assay is a rapid, reliable
and economical method for screening compounds for potential genetic activity at the
nucleotide level. A large database has been accumulated with this assay, confirming its ability
to detect genetically active compounds of most chemical classes with around 80 to
90% sensitivity and specificity.
With the exception of strain TA102, these strains require biotin as well as histidine for
growth. In strain TA102 the critical mutation in the histidine gene is located on a multicopy
plasmid pAQ1. This strain is particularly sensitive to the activities of oxidative and
cross-linking mutagens. The plasmid derivatives (TA98, TA100, TA97a and TA102) have
increased sensitivity to certain mutagens as the pKM101 plasmid codes for an error-prone
DNA repair system.
When exposed to a mutagen, some of the bacteria in the treated population, through chemical
interaction with the compound, undergo genetic changes which cause them to revert to a
non-histidine-requiring state and thus grow in the absence of exogenous histidine. Different
tester strains are used because each is mutated by particular chemical classes of compound. A
compound that is mutagenic in one strain need not be so in another.

Evaluation criteria:

For valid data, the test item was considered mutagenic in this assay if:
1. A concentration related increase in revertant numbers of ≥2-fold (in strains TA98, TA100,
TA1535 or TA97a) or ≥1.5-fold (in strain TA102) the concurrent vehicle control values
was observed.
The test item was regarded positive in this assay if the above criterion was met.
The test item was regarded negative in this assay if the above criterion was not met.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium, other: TA98, TA100, TA97a and TA102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

not determined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Evidence of toxicity in the form of a slight thinning of the background bacterial lawn was observed at 5000 μg/plate in strains TA100 and TA102 in the absence and presence of S-9 in Experiment 1 only.
Mutagenicity:
Data from control treatments confirmed the correct strain and assay functioning, and the data were accepted as valid.
Following treatment with QAW039-C1, an increase in revertant numbers of at least 2-fold the concurrent vehicle control was observed in strain TA1535 in the presence of S-9 in Experiment 1 (maximum of 2.1-fold) and Experiment 2 (maximum of 2.4-fold). According to the study plan, increases in revertant numbers of 2-fold the concurrent control would be considered evidence of mutagenicity in strain TA1535, however it should be noted that this
strain exhibits a low background mutant frequency. Since the increases in revertant numbers were reproducible between experiments with some evidence of a concentration-related response, it is considered that the increases observed show evidence of weak mutagenicity in
this strain.
No other increases in revertant numbers of at least 2-fold (1.5-fold for strain TA102) the concurrent vehicle controls were observed following any other strain treatments.

Applicant's summary and conclusion

Conclusions:

Under the testing conditions used and applying standard mutagenicity criteria, QAW039-C1
did not show evidence of mutagenicity in strains TA98, TA100, TA97a and TA102 in the
absence and presence of S-9 or in strain TA1535 in the absence of S-9. Under the testing
conditions used and applying standard mutagenicity criteria, QAW039-C1 showed some
evidence of a weak mutagenic potential in strain TA1535 in the presence of S-9.