3,3'-oxybis(ethyleneoxy)bis(propylamine)

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jan - Apr 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP compliant

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Version / remarks:

1997

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht; 22.10.2009

Type of assay:

mammalian cell gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

3,3'-oxybis(ethyleneoxy)bis(propylamine)

EC Number:

224-207-2

EC Name:

3,3'-oxybis(ethyleneoxy)bis(propylamine)

Cas Number:

4246-51-9

Molecular formula:

C10H24N2O3

IUPAC Name:

3,3'-[oxybis(ethane-2,1-diyloxy)]dipropan-1-amine

Specific details on test material used for the study:

- Name of test substance: 3,3’-Oxybis(ethyleneoxy)bis(propylamine)
- Batch identification: O 2895
- Purity/composition: 99.7 corr. area-%
- Homogeneity: The homogeneity of the test substance was guaranteed on account of the high purity and was ensured by mixing before preparation of the test substance solutions
- Storage stability: The stability of the test substance under storage conditions is guaranteed until 15 Jun 2013 as indicated by the sponsor
- Date of production: 15 Jun 2011
- Molecular weight: 220.3092 g/mol
- Physical state, appearance: Liquid, colorless, clear
- Storage conditions: Room temperature

Method

Target gene:

HPRT locus

Species / strain

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

- Type and identity of media: Treatment medium (4-hour exposure period): Ham's F12 medium containing stable glutamine and hypoxanthine; Culture medium and Treatment medium (24-hour exposure): Ham's F12 medium containing stable glutamine and hypoxanthine supplemented with 10% (v/v) fetal calf serum (FCS); Pretreatment medium ("HAT" medium): Ham's F12 medium supplemented with hypoxanthine (13.6 x 10E-3 mg/mL), aminopterin (0.18 x 10E-3 mg/mL), thymidine (3.88 x 10E-3 mg/mL), 10% (v/v) fetal calf serum (FCS); Selection medium ("TG" medium): Hypoxanthine-free Ham's F12 medium supplemented with 6-thioguanine (10 μg/mL), 1% (v/v) stable glutamine (200 mM), 10% (v/v) fetal calf serum (FCS). All media were supplemented with 1% (v/v) penicillin/streptomycin (stock solution: 10000 IU / 10000 μg/mL) and 1% (v/v) amphotericine B (stock solution: 250 μg/mL)
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes (Each batch used for mutagenicity testing was checked for mycoplasma contamination)
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital/β-naphthoflavone-induced rat liver S9 mix
- method of preparation of S9 mix
The S9 fraction was prepared in an AAALAC approved laboratory in accordance with the German Animal Welfare Act and the effective
European Council Directive. At least 5 male Wistar rats [Crl:WI(Han)] (200 - 300 g; Charles River Laboratories Germany GmbH) received 80 mg/kg b.w. phenobarbital i.p. and β-naphthoflavone orally (both supplied by Sigma-Aldrich, 82024 Taufkirchen, Germany) each on three consecutive days.
During this time, the animals were housed in Makrolon cages: central air conditioning with a fixed range of temperature of 20 - 24°C and a relative humidity of 30 - 70%. The day/night
rhythm was 12 hours (12 hours light from 6:00 – 18:00 hours and 12 hours darkness from 18:00 – 6:00 hours).
Standardized pelleted feed and tap water from bottles were available ad libitum. 24 hours after the last administration, the rats were sacrificed and the livers were prepared
using sterile solvents and glassware at a temperature of +4°C. The livers were weighed and washed in a weight-equivalent volume of a 150 mM KCl solution, then cut into small pieces
and homogenized in three volumes of KCl solution. After centrifugation of the homogenate at 9 000 x g for 10 minutes at +4°C, 5 mL portions of the supernatant (so-called S9 fraction)
were stored at -70°C to -80°C.

Test concentrations with justification for top dose:

1st Experiment: 4 hours exposure; 24 hours harvest time; with and without S9 mix: 0; 68.8; 137.5; 275.0; 550.0; 1100.0; 2200.0 µg/mL;
2nd Experiment: 24 hours exposure, 24 hours harvest time, without S9 mix: 0; 34.4; 68.8; 137.5; 275.0; 550.0; 1100.0; 2200.0 µg/mL; 4 hours exposure, 24 hours harvest time, with S9 mix: 0; 187.5; 375.0; 750.0; 1500.0; 2200.0 µg/mL
3rd Experiment: 24 hours exposure, 24 hours harvest time, without S9 mix: 0; 0.39; 0.78; 1.56; 3.13; 6.25; 12.50; 25.00; 50.00 µg/mL

The doses were selcted on the basis of the data and the observations from the pretest and taking into account the current guidelines.

Vehicle / solvent:

- Vehicle/solvent used: culture medium
- Justification for choice of solvent/vehicle: Due to the good solubility of the test substance in water, the aqueous culture medium (Ham's F12) was selected as vehicle

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

3-methylcholanthrene

ethylmethanesulphonate

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

EXPERIMENTAL PROCEDURE
- Preparation of test cultures: The stocks of cells (1.0-mL portions) were thawed at 37°C in a water bath. 0.5 mL were pipetted into 25 cm² plastic flasks containing 5 mL Ham's F12 medium (incl. 10% [v/v] FCS). The medium was replaced after 24 hours to remove any dead cells. After at least 2 passages, cells were taken for the experiment, and for these there was another passage to prepare test cultures.
- Pretreatment of cells with "HAT" medium: During the week prior to treatment, spontaneous HPRT-deficient mutants were eliminated by pretreatment with "HAT" medium. 3 – 5x10E+05 cells were seeded per flask (75 cm²) and incubated with "HAT" medium for 3 - 4 days. After that, a passage in Ham's F12 medium incl. 10% (v/v) FCS was followed with a subsequent incubation for a further 3 - 4 days.
- Attachment period: For each test group, about 1x10E+06 logarithmically growing cells per flask (175 cm²) were seeded into about 20 mL Ham's F12 medium supplemented with 10% (v/v) FCS and incubated for about 20 - 24 hours. Two flasks (one flask referred to as A and one flask referred to as B) were used for each test group.
- Exposure period: After the attachment period, the medium was removed from the flasks and the treatment medium was added. The cultures were incubated for the respective exposure period at 37°C, 5% (v/v) CO2 and ≥ 90% humidity.
- Expression period: The exposure period was completed by rinsing several times with HBSS. Then the flasks were topped up with at least 20 mL Ham's F12 medium incl. 10% (v/v) FCS and left to stand in the incubator for about 3 days (4-hour treatment) or 2 days (24-hour treatment). This was followed by the 1st passage. After an entire expression period of 7 – 9 days the cells were transferred into selection medium (2nd passage).
- Selection period: For selection of the mutants, six 75 cm² flasks with 3x10E+05 cells each from every treatment group, if possible, were seeded in 10 mL selection medium ("TG" medium) at the end of the expression period. The flasks were returned to the incubator for about 6 - 7 days. At the end of the selection period, the medium was removed and the remaining colonies were fixed with methanol, stained with Giemsa and counted.

NUMBER OF REPLICATIONS: Three independent experiments

DETERMINATION OF CYTOTOXICITY
- Cloning efficiency 1 (CE1; survival): For the determination of the influence of the test substance directly after the exposure period, per dose group about 200 cells were seeded in 25 cm² flasks in duplicate using 5 mL Ham's F12 medium incl. 10% (v/v) FCS. After an attachment period of 20 – 24 hours, the cells were treated with the vehicle, test substance or positive control for 4 hours or 24 hours. The exposure periods were completed by rinsing several times with HBSS. Then the flasks were topped up with 5 mL Ham's F12 medium incl. 10% (v/v) FCS.
- Cloning efficiency 2 (CE2; viability): For the determination of the mutation rate after the expression period, about 200 cells were separated during the transfer into selection medium (after 7 – 9 days) and seeded in two flasks (25 cm²) containing 5 mL Ham's F12 medium incl. 10% (v/v) FCS each. In all cases, after seeding of the cells the flasks were incubated for 5 - 8 days to form colonies. These colonies were fixed, stained and counted. The absolute and relative cloning efficiencies (%) were calculated for each test group.

EVALUATION
- Cytotoxicity (CE, CE1, CE2): The cloning efficiency (CE, %) was calculated for each test group as follows:
CE[absolute] = (total number of colonies in the test group)/(total number of seeded cells in the test group) x 100
CE[relative] = (CE[absolute of the test group])/(CE[absolute of the vehicle/negative control]) x 100
The number of colonies in every flask was counted and recorded. Using the formula above the values of absolute cloning efficiencies (CE[absolute], CE1[absolute] and/or CE2[absolute]) were calculated. Based on these values the relative cloning efficiencies (CE[relative], CE1[relative] and/or CE2[relative]) of the test groups were calculated and given in percentage compared with the respective CE[absolute] value of the corresponding vehicle/negative control (vehicle/negative control = 100%).
- Mutant frequency: The number of colonies in every flask was counted and recorded. The sum of the mutant colony counts within each test group was subsequently normalized to 10E+06 cells seeded. The uncorrected mutant frequency (MF[uncorr.]) per 10E+06 cells was calculated for each test group as follows:
MF[uncorr.] = (total number of mutant colonies)/(number of seeded cells) x 10E+06
The uncorrected mutant frequency was corrected with the absolute cloning efficiency 2 for each test group to get the corrected mutant frequency (MF[corr.]):
MF[corr.] = (MF[uncorr.])/(CE2[absolute]) x 100

CHECK OR DETERMINATION OF FURTHER PARAMETERS
- pH: Changes in the pH were recorded by a change in the indicator color in the culture medium (phenol red: no color change from pH 6.7 - 8.3). The pH was measured, at least for the two top doses and for the negative controls with and without S9 mix.
- Osmolarity: Osmolarity was measured, at least for the top dose and for the negative controls with and without S9 mix.
- Solubility: Test substance precipitation was checked immediately after treatment of the test cultures and at the end of treatment.
- Cell morphology: The test cultures of all test groups were examined microscopically at the end of exposure period with regard to cell morphology, which allows conclusions to be drawn about the attachment of the cells.

Evaluation criteria:

ACCEPTANCE CRITERIA:
The HPRT assay is considered valid if the following criteria are met:
- The absolute cloning efficiencies of the negative/vehicle controls should not be less than 50% (with and without S9 mix).
- The background mutant frequency in the negative/vehicle controls should fall within our historical negative control data range of 0.00 – 16.43 mutants per 10E+06 clonable cells.
- The positive controls both with and without S9 mix must induce distinctly increased mutant frequencies (historical positive control data).
- At least 4 dose levels ranging up to a toxic concentration or up to or beyond the limit of solubility under culture conditions should be tested. Freely soluble and apparently non-toxic substances are not tested at concentrations higher than 5 mg/mL or 10 mM.

ASSESSMENT CRITERIA:
A finding is assessed as positive if the following criteria are met:
- Increase of the corrected mutation frequencies (MF[corr.]) both above the concurrent negative control values and our historical negative control data range.
- Evidence of reproducibility of any increase in mutant frequencies.
- A statistically significant increase in mutant frequencies and the evidence of a dose-response relationship.
Isolated increases of mutant frequencies above our historical negative control range (i.e. 15 mutants per 10E+06 clonable cells) or isolated statistically significant increases without a dose-response relationship may indicate a biological effect but are not regarded as sufficient evidence of mutagenicity.
The test substance is considered non-mutagenic according to the following criteria:
- The corrected mutation frequency (MF[corr.]) in the dose groups is not statistically significant increased above the concurrent negative control and is within our historical negative control data range.

Statistics:

An appropriate statistical trend test was performed to assess a dose-related increase of mutant frequencies. The number of mutant colonies obtained for the test substance treated groups was compared with that of the respective negative control groups. A trend is judged as statistically significant whenever the p-value (probability value) is below 0.10 and the slope is greater than 0. However, both, biological and statistical significance will be considered together.

Results and discussion

Test results

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: The pH value of the test substance preparation was adjusted by adding small amounts of HCl.
- Precipitation: In this study, in the absence and the presence of S9 mix no precipitation in culture medium was observed up to the highest applied test substance concentration.

COMPARISON WITH HISTORICAL CONTROL DATA: In this study, no relevant increase in the number of mutant colonies was observed either without S9 mix or after the addition of a metabolizing system. In all experiments after 4 and 24 hours treatment with the test substance the values for the corrected mutation frequencies (MF[corr.]: 0.00 – 3.03 per 10+06 cells) were close to the respective vehicle control values (MF[corr.]: 0.26 – 3.52 per 10E+06 cells) and clearly within the range of our historical negative control data (without S9 mix: MF[corr.]: 0.00 – 16.43 per 10+06 cells; with S9 mix: MF[corr.]: 0.00 – 15.83 per 10+06 cells). The positive control substances EMS (without S9 mix; 300 μg/mL) and MCA (with S9 mix; 20 μg/mL) induced clearly increased mutant frequencies as expected. The values of the corrected mutant frequencies (without S9 mix: MF[corr.]: 75.04 – 452.96 per 10+06 cells; with S9 mix: MF[corr.]: 55.07 – 88.91 per 10E+06 cells) were clearly within our historical positive control data range (without S9 mix: MF[corr.]: 47.35 – 1 338.10 per 10E+06 cells; with S9 mix: MF[corr.]:
26.29 – 413.54 per 10E+06 cells).

ADDITIONAL INFORMATION ON CYTOTOXICITY: Cytotoxic effects indicated by clearly reduced cloning efficiencies of below 20% of control were observed in the 1st Experiment in the absence of S9 mix after 4 hours treatment and in the 2nd Experiment in the presence and absence of S9 mix. In the 3rd Experiment in the absence of S9 mix after 24hours treatment there was a decrease in the number of colonies in the highest applied concentrations. In detail, in the 1st Experiment in the absence of S9 mix, there was a decrease in the number of colonies at the highest applied concentration of 2 200.0 μg/mL (CE1 relative: 0.0%) after an exposure period of 4 hours. No cytotoxicity was observed in the presence of S9 mix. The cell densities were not distinctly reduced. In the 2nd Experiment in the absence of S9 mix after 24 hours treatment strong cytotoxicity was observed from the lowest concentration onward. Thus, with no remaining test group this experimental part was discontinued. The cell densities were distinctly reduced. In addition, in the presence of S9 mix, there was a decrease in the number of colonies at the highest applied concentration of 2200.0 μg/mL (CE1 relative: 0.0%) after an exposure period of 4 hours. In this experimental part the cell densities were not distinctly reduced. In the 3rd Experiment in the absence of metabolic activation after 24 hours treatment a decrease in the number of colonies was observed at the concentration of 6.25 μg/mL and above (CE1 relative: 0.0%). The cell densities were distinctly reduced.

CELL MORPHOLOGY: There were no adverse observations on cell morphology (cell attachment) in the absence and presence of S9 mix in the 1st Experiment and in the presence of S9 mix in the 2nd Experiment. After 24 hours treatment in the absence of S9 mix, in the 2nd and 3rd Experiment the morphology and attachment of the cells was adversely influenced at the highest applied concentrations.

Any other information on results incl. tables

Table 4: Summary of results - experimental parts without S9 mix

Exp.	Exposure period [h]	Test groups [µg/mL]	S9 mix	Prec.*	Genotoxicity** MFcorr. [per 10^6cells]	Cytotoxicity***
						CE1 [%]	CE2 [%]
1	4	Negative control	-	-	3.52	100.0	100.0
		68.8	-	-	n.c.^1	96.4	n.c.^1
		137.5	-	-	0.27	90.9	103.8
		275.0	-	-	1.32	96.9	100.5
		550.0	-	-	1.37	98.1	99.3
		1100.0	-	-	0.81	91.6	103.7
		2200.0	-	-	n.c.^2	0.0	n.c.^2
		Positive control^1	-	-	75.04	95.6	92.1
2	24	Negative control	-	-	n.c.^3	100.0	n.c.^3
		34.4	-	-		0.0	n.c.^3
		68.8	-	-		0.0	n.c.^3
		137.5	-	-		0.0	n.c.^3
		275.0	-	-		0.0	n.c.^3
		550.0	-	-		0.0	n.c.^3
		1100.0	-	-		0.0	n.c.^3
		2200.0	-	-		0.0	n.c.^3
		Positive control^1	-	-		69.4	n.c.^3
3	24	Negative control	-	-	0.26	100.0	100.0
		0.39	-	-	2.04	112.9	103.0
		0.78	-	-	3.03	113.3	94.2
		1.56	-	-	2.97	117.7	97.0
		3.13	-	-	0.54	64.9	103.0
		6.25	-	-	n.c.^2	0.0	n.c.^2
		12.50	-	-	n.c.^2	0.0	n.c.^2
		25.00	-	-	n.c.^2	0.0	n.c.^2
		50.00	-	-	n.c.^2	0.0	n.c.^2
		Positive control^1	-	-	452.96	102.9	66.6

* Precipitation in culture medium at the end of exposure period

** Mutant frequency MF_corr.: mutant colonies per 10⁶ cells corrected with the CE₂ value

*** Cloning efficiency related to the respective vehicle control

n.c.¹ Culture was not continued since a minimum of only four analysable concentrations are required

n.c.² Culture was not continued due to strong cytotoxicity

n.c.³ Culture was not continued due to missing the OECD recommendations

¹ EMS 300 µg/mL

 

Table 5: Summary of results - experimental parts with S9 mix

Exp.	Exposure period [h]	Test groups [µg/mL]	S9 mix	Prec.*	Genotoxicity** MFcorr. [per 10^6cells]	Cytotoxicity***
						CE1 [%]	CE2 [%]
1	4	Negative control	+	-	2.63	100.0	100.0
		68.8	+	-	n.c.^1	104.1	n.c.^1
		137.5	+	-	n.c.^1	103.0	n.c.^1
		275.0	+	-	1.36	101.7	103.7
		550.0	+	-	2.53	106.8	98.2
		1100.0	+	-	0.56	86.4	105.9
		2200.0	+	-	1.58	39.1	110.8
		Positive control^2	+	-	55.07	99.7	105.9
2	24	Negative control	+	-	1.58	100.0	100.0
		187.5	+	-	0.00	108.8	^93.0
		375.0	+	-	2.10	105.4	96.1
		750.0	+	-	1.22	80.2	100.4
		1500.0	+	-	2.33	102.7	104.7
		2200.0	+	-	0.00	8.4	98.1
		Positive control^2	+	-	88.91	103.3	102.5

* Precipitation in culture medium at the end of exposure period

** Mutant frequency MF_corr.: mutant colonies per 10⁶ cellscorrected with the CE₂ value

*** Cloning efficiency related to the respective vehicle control

n.c.¹ Culture was not continued since a minimum of only four analysable concentrations are required

² MCA 20 µg/mL

Applicant's summary and conclusion

Conclusions:

The test substance is not mutagenic in the HPRT locus assay under in vitro conditions in CHO cells in the absence and the presence of metabolic activation.

Executive summary:

The study was performed according to OECD guideline 476 in compliance with GLP (reliability 1).

The test substance was assessed for its potential to induce gene mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus in Chinese hamster ovary (CHO) cells in vitro. Three independent experiments were carried out, all with and without the addition of liver S9 mix from induced rats (exogenous metabolic activation). Based on the observations and the toxicity data of a previously performed in vitro chromosome aberration assay (data not shown) the following concentrations were tested and the test groups in bold type evaluated:

1st Experiment

without S9 mix (4-hour exposure period): 0; 68.8; 137.5; 275.0; 550.0; 1100.0; 2200.0 μg/mL

with S9 mix (4-hour exposure period): 0; 68.8; 137.5; 275.0; 550.0; 1100.0; 2200.0 μg/mL

2nd Experiment

without S9 mix (24-hour exposure period): 0; 34.4; 68.8; 137.5; 275.0; 550.0; 1100.0; 2200.0 μg/mL

with S9 mix (4-hour exposure period): 0; 187.5; 375.0; 750.0; 1500.0; 2200.0 μg/mL

3rd Experiment

without S9 mix (24-hour exposure period): 0; 0.39; 0.78; 1.56; 3.13; 6.25; 12.50; 25.00; 50.00 μg/mL

After an attachment period of 20 - 24 hours and a treatment period of 4 hours both with and without metabolic activation and 24 hours without metabolic activation, an expression phase of about 6 - 8 days and a selection period of about 1 week followed. The colonies of each test group were fixed with methanol, stained with Giemsa and counted.

The vehicle controls gave mutant frequencies within the range expected for the CHO cell line. Both positive control substances, EMS and MCA, led to the expected increase in the frequencies of forward mutations.

In this study, in the 1st, 2nd and 3rd Experiment in the absence and in the 2nd Experiment in the presence of metabolic activation the highest concentrations evaluated for gene mutations were clearly cytotoxic.

On the basis from the results of the present study, the test substance did not cause any relevant and dose-dependent increase in the mutant frequencies both without S9 mix and after adding a metabolizing system in three experiments performed independently of each other.

Thus, under the experimental conditions of this study, the test substance is not mutagenic in the HPRT locus assay under in vitro conditions in CHO cells in the absence and the presence of metabolic activation.