2-Fluor-4-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-phenylboronic acid

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The test item did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used. Therefore, the test item is considered to be non-mutagenic in this Salmonella typhimurium and Escherichia coli reverse mutation assay.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-09-22 to 2017-10-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

other: TA 1535, TA 1537, TA 98, TA 100, and WP2 uvrA

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital/Beta-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

Pre-Experiment/Experiment I: 3; 10; 33; 100; 333; 1000; 2500; and 5000 µg/plate
Experiment II: 10; 33; 100; 333; 1000; 2500; and 5000 µg/plate

Vehicle / solvent:

Solvent used: DMF
Justification for choice of solvent: best suitable solvent, because of its solubility properties and its relative nontoxicity to the bacteria

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: 4-nitro-o-phenylene-diamine, 2-aminoanthracene

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar plate incorporation; pre-incubation

DURATION:
Preincubation period: 60 Minutes
exposure duration: 72 hours

NUMBER OF REPLICATIONS: 3 plates for each concentration including the controls

DETERMINATION OF CYTOTOXICITY: Evident as a reduction in the number of spontaneous revertants (below the induction factor of 0.5) or a clearing of the bacterial background lawn.

Evaluation criteria:

A test item is considered as a mutagen if a biologically relevant increase in the number of revertants exceeding the threshold of twice (strains TA 98, TA 100, and WP2 uvrA) or thrice (strains TA 1535 and TA 1537) the colony count of the corresponding solvent control is observed.
A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration.
An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment.
A dose dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent second experiment. However, whenever the colony counts remain within the historical range of negative and solvent controls such an increase is not considered biologically relevant.

Statistics:

According to the OECD guideline 471, a statistical analysis of the data is not mandatory.

Key result

Species / strain:

other: TA 1535, TA 1537, TA 98, TA 100, and WP2 uvrA

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

in strains TA 1535, TA 1537, TA 98 and WP2 uvrA (only experiment II)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST SPECIFIC CONFOUNDING FACTORS
Effects of pH: none
Water solubility: not soluble
Precipitation: The test item precipitated in the overlay agar in the test tubes from 333 to 5000 µg/plate in both experiments. Precipitation of the test item in the overlay agar on the incubated agar plates was observed from 333 to 5000 µg/plate in experiment I and from 1000 to 5000 µg/plate in experiment II. The undissolved particles had no influence on the data recording.
Other confounding effects: The tester strain TA 98 showed an extensive bacterial background growth indicated by a more dense background lawn. Thus, in experiment I all plates incubated with strain TA 98 were scored manually. The revertant rates of both negative control groups each were within our laboratory’s historical negative control range for strain TA 98 and, therefore, this observation has to be regarded to have no detrimental impact on the validity and outcome of the study.

COMPARISON WIT HISTORICAL CONTROL DATA: performed, no deviations
ADDITIONAL INFORMATION ON CYTOTOXICITY: Toxic effects, evident as a reduction in the number of revertants (below the indication factor of 0.5), occurred in several strains with and without metabolic activation in experiment II (pre-incubation method) from about 1000 µg/plate onward.

Summary of Experiment I

Metabolic Activation	Test Group	Dose Level (per plate)	TA 1535 Revertant Colony Counts (Mean ± SD)	TA 1537 Revertant Colony Counts (Mean ± SD)	TA 98 Revertant Colony Counts (Mean ± SD)	TA 100 Revertant Colony Counts (Mean ± SD)	WP2 uvrA Revertant Colony Counts (Mean ± SD)
Without	DMF		8 ± 2	7 ± 2	13 ± 1^B M	178 ± 3	30 ± 2
Activation	Untreated		6 ± 1	8 ± 2	15 ± 3^B M	192 ± 19	41 ± 2
	Test item	3 µg	6 ± 1	8 ± 3	12 ± 2^B M	203 ± 4	32 ± 2
		10 µg	9 ± 2	7 ± 2	11 ± 1^B M	190 ± 10	27 ± 5
		33 µg	9 ± 1	8 ± 3	11 ± 3^B M	195 ± 14	34 ± 7
		100 µg	10 ± 2	8 ± 4	12 ± 3^B M	189 ± 13	30 ± 3
		333 µg	10 ± 5^P	9 ± 3^P	15 ± 5^P B M	180 ± 21^P	32 ± 7^P
		1000 µg	6 ± 2^P M	8 ± 1^P M	13 ± 2^P B M	163 ± 9^P M	27 ± 5^P M
		2500 µg	7 ± 2^P M	5 ± 1^P M	11 ± 3^P B M	165 ± 6^P M	24 ± 3^P M
		5000 µg	9 ± 1^P M	5 ± 1^P M	8 ± 2^P B M	155 ± 21^P M	20 ± 2^P M
	NaN3	10 µg	1333 ± 31			2166 ± 31
	4-NOPD	10 µg			363 ± 12^B M
	4-NOPD	50 µg		76 ± 7
	MMS	2.0 µL					1027 ± 65
With	DMF		10 ± 2	9 ± 3	12 ± 1^B M	158 ± 13	42 ± 9
Activation	Untreated		12 ± 3	9 ± 3	15 ± 3^B M	176 ± 18	36 ± 4
	Test item	3 µg	13 ± 4	12 ± 5	11 ± 2^B M	189 ± 15	36 ± 4
		10 µg	8 ± 2	11 ± 5	12 ± 1^B M	176 ± 9	41 ± 6
		33 µg	9 ± 4	10 ± 4	15 ± 3^B M	170 ± 13	45 ± 9
		100 µg	8 ± 3	10 ± 2	12 ± 1^B M	167 ± 23	41 ± 4
		333 µg	9 ± 4^P	12 ± 3^P	11 ± 2^P B M	161 ± 19^P	44 ± 2^P
		1000 µg	11 ± 2^P M	7 ± 1^P M	14 ± 3^P B M	164 ± 8^P M	28 ± 1^P M
		2500 µg	9 ± 3^P M	8 ± 1^P M	15 ± 2^P B M	171 ± 4^P M	25 ± 4^P M
		5000 µg	8 ± 2^P M	9 ± 1^P M	15 ± 1^P B M	141 ± 4^P M	23 ± 7^P M
	2-AA	2.5 µg	469 ± 39	119 ± 4	3965 ± 223^B M	3698 ± 173
	2-AA	10.0 µg					526 ± 39

Summary of Experiment II

Metabolic Activation	Test Group	Dose Level (per plate)	TA 1535 Revertant Colony Counts (Mean ± SD)	TA 1537 Revertant Colony Counts (Mean ± SD)	TA 98 Revertant Colony Counts (Mean ± SD)	TA 100Revertant Colony Counts (Mean ± SD)	WP2 uvrARevertant Colony Counts (Mean ± SD)
Without	DMF		9 ± 2	10 ± 1	24 ± 2	132 ± 9	38 ± 6
Activation	Untreated		8 ± 2	10 ± 4	31 ± 5	180 ± 14	44 ± 4
	Test item	10 µg	10 ± 1	10 ± 1	21 ± 5	137 ± 16	32 ± 7
		33 µg	9 ± 3	8 ± 2	25 ± 6	136 ± 10	32 ± 8
		100 µg	10 ± 2	10 ± 1	21 ± 2	141 ± 6	37 ± 2
		333 µg	10 ± 4	12 ± 2	30 ± 9	145 ± 9	33 ± 5
		1000 µg	9 ± 2^P	10 ± 5^P	30 ± 5^P	131 ± 5^P	41 ± 3^P
		2500 µg	8 ± 1^P M	7 ± 2^P M	14 ± 5^P M	115 ± 10^P M	27 ± 3^P M
		5000 µg	7 ± 1^P M	3 ± 1^P M	6 ± 2^P M	97 ± 5^P M	17 ± 3^P M
	NaN3	10 µg	1118 ± 42			1584 ± 40
	4-NOPD	10 µg			343 ± 7
	4-NOPD	50 µg		98 ± 2
	MMS	2.0 µL					921 ± 6
With	DMF		13 ± 6	16 ± 5	36 ± 8	131 ± 6	40 ± 6
Activation	Untreated		11 ± 1	18 ± 3	43 ± 5	179 ± 17	59 ± 11
	Test item	10 µg	12 ± 4	15 ± 4	37 ± 9	119 ± 24	47 ± 5
		33 µg	10 ± 1	17 ± 4	35 ± 6	141 ± 6	49 ± 14
		100 µg	15 ± 1	14 ± 3	36 ± 4	123 ± 26	50 ± 10
		333 µg	13 ± 2	13 ± 2	26 ± 5	120 ± 16	37 ± 11
		1000 µg	9 ± 2^P M	6 ± 2^P M	26 ± 4^P M	156 ± 18^P	49 ± 7^P
		2500 µg	7 ± 1^P M	6 ± 1^P M	23 ± 3^P M	73 ± 10^P M	26 ± 3^P M
		5000 µg	5 ± 2^P M	4 ± 1^P M	13 ± 3^P M	62 ± 9^P M	14 ± 3^P M
	2-AA	2.5 µg	427 ± 16	124 ± 14	3194 ± 284	3157 ± 118
	2-AA	10.0 µg					414 ± 21

Key to Plate Postfix Codes:              

P: Precipitate

M: Manuel Count

B: Extensive bacterial colony growth

Key to positive controls:

NaN3: sodium azide

4 -NOPD: 4 -nitro-o-phenylene-diamine

MMS: methyl methane sulfonate

2-AA: 2 -aminoanthracene

Conclusions:

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used.
Therefore, the test item is considered to be non-mutagenic in this Salmonella typhimurium and Escherichia coli reverse mutation assay.

Executive summary:

The test item was assessed for its potential to induce gene mutations according to the plate incorporation test (experiment I) and the pre-incubation test (experiment II) usingSalmonella typhimuriumstrains TA 1535, TA 1537, TA 98, TA 100, and theEscherichia colistrain WP2 uvrA.

The assay was performed in two independent experiments both with and without liver microsomal activation. Each concentration and the controls were tested in triplicate. The test item was tested at the following concentrations:

Experiment I:                             3; 10; 33; 100; 333; 1000; 2500; and 5000 µg/plate

Experiment II:                           10; 33; 100; 333; 1000; 2500; and 5000 µg/plate

The test item precipitated in the overlay agar in the test tubes from 333 to 5000 µg/plate in both experiments. Precipitation of the test item in the overlay agar on the incubated agar plates was observed from 333 to 5000 µg/plate in experiment I and from 1000 to 5000 µg/plate in experiment II. The undissolved particles had no influence on the data recording.

The plates incubated with the test item showed normal background growth up to 5000 µg/plate with and without S9 mix in all strains used, except strain TA 98in experiment I in the absence and presence of metabolic activation. The tester strain TA 98 showed an extensive bacterial background growth indicated by a more dense background lawn. Thus, in experiment I all plates incubated with strain TA 98 were scored manually. The revertant rates of both negative control groups each were within our laboratory’s historical negative control range for strain TA 98 and, therefore, this observation has to be regarded to have no detrimental impact on the validity and outcome of the study.

Toxic effects, evident as a reduction in the number of revertants (below the induction factor of 0.5), were observed at the following concentrations (µg/plate):

Strain	Experiment I without S9 mix	Experiment I with S9 mix	Experiment II without S9 mix	Experiment II with S9 mix
TA 1535	/	/	/	5000
TA 1537	/	/	5000	1000 – 5000
TA 98	/	/	5000	5000
TA 100	/	/	/	/
WP2 uvrA	/	/	/	5000

No substantial increase in revertant colony numbers of any of the five tester strains was observed following treatment with the test item at any concentration level, neither in the presence nor absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance.

Appropriate reference mutagens were used as positive controls. They showed a distinct in­crease in induced revertant colonies.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

A reliable and suitable study is available to examine the mutagenic potential of the test item. Based on the data provided, the test item is not classified for mutagenicity according to Regulation (EC) No 1272/2008.