6-[(p-tosyl)amino]hexanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2012-2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study was conducted by a GLP accredited laboratory using OECD Testing Guideline 422. The study was conducted on 6-[(p-Tosyl)amino]hexanoic acid, which is the carboxylic acid component of the registered substance i.e. tosyl salt.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD 422 Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Tosyl carboxylic acid

IUPAC Name:

Tosyl carboxylic acid

Constituent 2

Reference substance name:

6-[(p-Tosyl)amino]hexanoic acid

IUPAC Name:

6-[(p-Tosyl)amino]hexanoic acid

Constituent 3

Reference substance name:

6-[[(4-methylphenyl)sulphonyl]amino]hexanoic acid

EC Number:

278-934-5

EC Name:

6-[[(4-methylphenyl)sulphonyl]amino]hexanoic acid

Cas Number:

78521-39-8

IUPAC Name:

6-{[(4-methylphenyl)sulfonyl]amino}hexanoic acid

Test material form:

solid: crystalline

Details on test material:

- Physical state: solid, white crystalline powder
- Batch No.: 110526S
- Expiry date: 26.05.2013
- Purity: 99.24% (taken as 100%)
- Instructions for storage: Room temperature, tighly closed container, cool, dry, only in original container
- Colour: white
- Odour: odourless

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Germany, D-97633 Sulzfeld
- Age at purchase: 11 weeks
- weight rage at time of grouping: males, 175-200 g
- Fasting period before study: no
- Housing: 2 per cage,
- Cages: TECHNIPLAST filter top cages type 2145 F with an G-Temp (PSU) durable filter cover, 480x265x210 mm³, floor area 940 cm²,
- Source: Techniplast Company, Italy
- Diet: ad libitum, M3, BONAGRO Ltd., reg. CZ 10174, Czech Republic
- Water: ad libitum, tap water
- Acclimation period: 9 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 40 - 70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE: suspension in water
- Amount of vehicle: 10 ml/kg given at similar times each day

Analytical verification of doses or concentrations:

no

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1 (probably) (male animals: see Endpoint study record in section 7.5.1 "Repeated dose Toxicity")
- Length of cohabitation: until copulation/ up to 14 days
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug / sperm in vaginal smear referred to as day 0 of pregnancy
- M/F ratio per cage: 1/1
- Length of cohabitation: Each morning the females were examined for the presence of sperm in vaginal lavages.
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged individually.
- Any other deviations from standard protocol: no

Duration of treatment / exposure:

males: 54 administrations, (2 weeks before mating, 2 weeks during mating and 26 days after mating period)
females: 14 days pre-mating period and until mating, through the pregnancy period (assuming 20 days pregnancy) until lactation day 3 after delivery (4 days lactation period)

Frequency of treatment:

daily by stomach tube

Duration of test:

up to 54 days

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 100, 400, 1600 mg/kg bw./day
Basis:
actual ingested

No. of animals per sex per dose:

12
satellite group: (1600 mg/kg bw./day ):5 individuals (5 females and 5 males)

Control animals:

yes

Details on study design:

- Control groups: drinking water
- Dose selection rationale: Results of an acute toxicity study with oral administration to male and female rats
- Result: no effects up to and including 2000 mg/kg bw.
- Rationale for animal assignment: randomly grouped
- Section schedule rationale: all animals were sacrificed

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: on administration days 1, 8, 15, 22, 29, 36, 42, 50 and on day of autopsy

FOOD CONSUMPTION : 2 weeks before mating, after 2 week mating period and weekly until the end of the study

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 14 (before mating) and prior to autopsy from the satellite groups and from the control and high dose group.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:day 14 (before mating) and prior to autopsy from the satellite groups and from the control and high dose group.

URINALYSIS: No

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Number of corpora lutea: Yes
- Number of implantations: Yes

Fetal examinations:

- External examinations: Yes: [all per litter]

Statistics:

Statistical evaluation was operated using the software SPPS version 16.0. Group data were represented by mean, standard deviation and median. Statistical analysis in case of date measured once during the study (organ weight, haematology, clinical chemistry) : Mann-Whitney U test for pairwise comparison between control and individual experimental groups on significance level alpha = 0.05.
Statistical analysis in cas of repeated data measurement (body weight, food intake): Repeated measures ANOVA (procedure General Linear Model (GLM) for Repeated Measures in SPSS statistical software).

Indices:

implantation/fertility index, delivery index, live birth index, neonatal survival rate, copulation index, lactation status

Historical control data:

no

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Effect levels (maternal animals)

1

Dose descriptor:

NOEL

Effect level:

400 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: other:

2

Dose descriptor:

LOEL

Effect level:

1 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: other:

3

Dose descriptor:

NOAEL

Effect level:

400 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Daily dosages of 0, 100, 400, and 1600 mg/kg bw of the test substance. were administered by stomach tube to groups of 12 male and female rats. Treatment of males: 54 administrations, (2 weeks before mating, 2 weeks during mating and 26 days after mating period), treatment of females: 14 days pre-mating period and until mating, through the pregnancy period (assuming 20 days pregnancy) until lactation day 3 after delivery (4 days lactation period) for 54 days.
Additional satelite groups of 5 male and 5 female were treated with 0 and 1600 mg ASC plus/kg bw. and used for observation of reversibility, persistence or delayed occurence of systemic toxic effects for at least 14 days post treatment.
The test-article was formulated in drinking water and administered in 10 ml/kg bw..
At dosages of 100 and 400 mg/kg bw. the animals showed no differences to the control animals (NOAEL).
1600 mg ASC plus/kg bw. may have induced an influence on the body weight gain of the males and the survival of pups until day 4 after birth.
NOAEL: 400 mg/kg bw.

Executive summary:

The developmental toxicity of the test substance was determined in accordance with the OECD Guideline for Testing of Chemicals 422. Doses of 0, 100, 400, and 1600 mg/kg bw/day of the test substance were administered by stomach tube to groups of 12 male rats for 54 days. The test-article was formulated in drinking water and administered in 10 ml/kg bw. Histopathology and gross necropsy did not reveal any test-article related changes. The organ weights showed some statistically significant differences, but these were not related to dosage or not affirmed by the findings in other groups, for example by the results of the satellite groups.

The same is true for the statistical significant differences of the haematological parameters and the result of the clinical chemistry, especially decreased activities of the liver enzymes in the blood. These are merely statistical effects without biological relevance.

Two effects with a possible relation to the oral administration of the test substance were observed:

- At birth no differences were observed between the groups, but on day 4 after birth a higher number of dead pups was counted in the high-dose level group.

- With male rats a dose dependent decrease in body weight is observed. This effect is in the highest dose group statistically significant and confirmed by the satellite group but not confirmed by the body weight development of the females and not confirmed by the food consumption of males and females.

Although the influence of an infection with parasites seems possible and may explain both effects, a non-specific influence of the test substance cannot be excluded. The daily administration of a suspension of the test substance in 10 ml/ kg bw. may have led to a reduced appetite of the animals. This could be especially true for the highest dosage group, as here the suspension was relatively dense. It is also possible that there was an osmotic effect from non-resorbed test substance in the intestine. At doses of 100 and 400 mg/kg bw/day the animals showed no differences to the control animals (NOEL). A dose of 1600 mg/kg bw/day may have induced an influence on the body weight gain of the males and the survival of pups until day 4 after birth. With regard to the results of the present study 400 mg/kg bw/day can be defined as "No Observed Adverse Effect Level" (NOAEL) for the developmental toxicity. The test substance was the carboxylic acid component of the registered substance (tosyl salt). Read-across between the tosyl salt carboxylic acid (6-[(p-Tosyl)amino]hexanoic acid) and the registered substance is considered justified as the registered substance is manufactured directly from 6-[(p-Tosyl)amino]hexanoic acid by simple neutralisation with triethanolamine (TEA). Other than ionization of the carboxylic acid group, the 6-[(p-Tosyl)amino]hexanoic acid remains chemically unchanged upon salt formation. In water, the acid and amine components of 6-[(p-Tosyl)amino]hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol (1:1) dissociate completely and behave essentially as independent substances. Since TEA can be considered non-hazardous, it is the acid component of the salt that will have a more significant impact on the outcome of any (eco)toxicological or environmental tests. The pKa of the carboxylic acid group in 6-[(p-Tosyl)amino]hexanoic acid (pKa = 4.90) is the same in the free acid as it is in the TEA salt. As a result, 6-[(p-Tosyl)amino]hexanoic acid will respond to changes of pH in the same way whether it is in the salt form or as the parent carboxylic acid and hence it’s bioavailability will be the same.