3-mercaptopropionic acid

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:

06-JUN-2006 to 13-JUN-2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study; GLP

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD 422

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Methyl 3-mercaptopropionate

EC Number:

220-912-4

EC Name:

Methyl 3-mercaptopropionate

Cas Number:

2935-90-2

Molecular formula:

C4H8O2S

IUPAC Name:

methyl 3-sulfanylpropanoate

Details on test material:

- Name of test material (as cited in study report): Methyl 3-mercaptopropionate
- Molecular formula (if other than submission substance): C4H8O2S
- Molecular weight (if other than submission substance): 120.17
- Smiles notation (if other than submission substance): COC(=O)CCS
- InChl (if other than submission substance): InChI=1/C4H8O2S/c1-6-4(5)2-3-7/h7H,2-3H2,1H3
- Physical state: Liquid
- Analytical purity: 99.81%
- Purity test date: 2006-01-25
- Lot/batch No.: 6ATMMP09
- Expiration date of the lot/batch: 2007-01-01
- Stability under test conditions: stability and homogeneity were analytically verified
- Storage condition of test material: At room temperature (20 ± 5°C)/under nitrogen

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd, Laboratory Animal Services, Wölferstrasse 4, CH-4414 Füllinsdorf / Switzerland
- Age at study initiation: 10 weeks
- Weight at study initiation: Males: 286 - 331 grams, Females: 180 - 207 grams
- Fasting period before study: only before blood sampling
- Housing: Animals were housed in Makrolon cages (type-3) with wire mesh tops and standard granulated softwood bedding. During the pre-pairing period, males and females were housed individually. Cages of males were interspersed amongst those holding females to promote the development of regular estrus cycles. During the pairing period, rats were housed one male/one female in Makrolon pairing cages. After mating or at the end of the pairing period, the males and the females were housed individually again. During the lactation period (until day 4 of lactation), dams were housed together with their litters.
- Diet: Pelleted standard Kliba 3433 rat/mouse maintenance diet (Provimi Kliba AG, CH-4303 Kaiseraugst/Switzerland) available ad libitum
- Water: ad libitum
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3°C
- Humidity (%): 30 - 70%
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 13-JUN-2006 To: 30-JUL-2006

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test item was weighed into a glass beaker on a tared precision balance and approximately 80% of the vehicle was added (w/v). Using an appropriate homogenizer a homogenous mixture was prepared. Having obtained a homogenous mixture, vehicle was added until the required final volume was achieved. Separate formulations were prepared for each concentration.
During the daily administration period homogeneity of the test item in the vehicle was maintained using a magnetic stirrer.


VEHICLE
- Justification for use and choice of vehicle (if other than water): corn oil is the vehicle of choice for substances with low water solubility
- Concentration in vehicle: 6.25, 12.50, 25.00 mg/mL
- Amount of vehicle (if gavage): 4 mL/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples for determination of concentration, homogeneity and stability (7 days) of the dose formulations were taken during the first week of the administration period. Additionally, samples for determination of concentration and homogeneity were taken during the last week of the administration period.
On each occasion three samples of approximately 2 g were taken from the top, middle and bottom of each formulation and transferred into flat bottomed flasks. The samples were frozen (-25°C to -15°C) pending analysis. Samples were sent on dry ice to Dr. D. Flade, RCC Ltd, Environmental Chemistry & Pharmanalytics, CH-4452 Itingen / Switzerland. Analysis was performed using a method developed by RCC Ltd. After analysis, the analytical results were communicated to the Study Director. Upon receipt and evaluation of these results the Study Director decided about discarding the samples.

Details on mating procedure:

After the animals had received the test item for 14 days, the pairing period was initiated while dosing was continued.
During the pairing period females were housed with males (one male : one female) in special automatic mating cages, i.e. with synchronized timing to initiate the nightly mating period, until evidence of copulation was observed.
This system reduces the variation in the copulation times of the different females.
Females were removed and housed individually if:
a) a copulation plug was observed, and / or
b) the daily vaginal smear was sperm-positive.
This day was designated day 0 post coitum.
Females showing no-evidence of copulation were sacrificed 24-26 days after the last day of the pairing period and, if indicated, the reproductive organs examined histopathologically in order to ascertain the reason for the infertility.

Duration of treatment / exposure:

males: at least 28 days; females: for 14 days prior to pairing, through pairing and gestation until day 4 post partum

Frequency of treatment:

daily

Duration of test:

entire pregnany until spontaneous delivery

Doses / concentrations

Remarks:

Doses / Concentrations:
25, 50 and 100 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

Sex: male/female
Duration of test: up to 28 days in males; up to 51 days in females

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations: mortality, clinical signs. Additionally, the females were observed for signs of difficult or prolonged parturition.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once prior to the first test item administration and weekly thereafter.


BODY WEIGHT: Yes
- Time schedule for examinations: daily


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: on the day before or on the day of scheduled necropsy
- Anaesthetic used for blood collection: Yes, isoflurane
- Animals fasted: Yes
- How many animals: 5 per sex per group
- Parameters:
Erythrocyte count, Hemoglobin concentration distribution width, Haemoglobin Platelet count, Haematocrit Total leukocyte count, Mean corpuscular volume, Differential leukocyte count, Red cell volume distribution width, Mean corpuscular hemoglobin concentration, Mean corpuscular haemoglobin
Coagulation: Thromboplastin time, Activated partial thromboplastin time



CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:on the day before or on the day of scheduled necropsy
- Animals fasted: Yes
- How many animals: 5 per sex per group
- Parameters:
Glucose, Sodium, Urea, Potassium, Creatinine, Chloride, Bilirubin, total Calcium, total Cholesterol, inorganic Phosphorus, Aspartate aminotransferase, total Protein, Alanine aminotransferase, Albumin, Bile acids, Globulin, Alkaline phosphatase, Albumin/Globulin ratio, Gamma-glutamyl-transferase


URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: At one time during the study (males: shortly before scheduled sacrifice; females: on day 3 or 4 post partum) relevant parameters were evaluated for five P generation males and five P generation females randomly selected from each group.
- Dose groups that were examined: all
- Battery of functions tested: Cage side observations, Hand-held observations, Open field observations, Categorical observations, Measurements / Counts: hind limb / fore limb grip strength, landing foot splay, rectal temperature.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: histopathology
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: No
- Number of implantations: No
- Number of early resorptions: No
- Number of late resorptions: No
- Other: histopathology on ovary and uterus w/ vagina

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: No
- Skeletal examinations: No
- Head examinations: No

Statistics:

The following statistical methods were used to analyze body weights, food consumption, reproduction and skeletal examination data:
• Means and standard deviations of various data were calculated and included in the report.
• If the variables could be assumed to follow a normal distribution, the Dunnett t-test, based on a pooled variance estimate, was used for intergroup comparisons (i.e. single treatment groups against the control group).
• The Steel test (rank test) was applied when the data could not be assumed to follow a normal distribution.
• Fisher's Exact test for 2x2 tables was applied if the variables could be dichotomized without loss of information.

Indices:

Mating index: no. of females mated/ no. of females paired
Fertility index: no. of pregnant females / no. of females mated
Gestation index: no. of litters with live pups / no. of pregnant females

Historical control data:

none

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

>= 100 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

>= 100 mg/kg bw/day

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Result: no effects on development at the highest dose tested (100 mg/kg bw/d)

There were no treatment-related effects on pup survival or litter size from birth through to scheduled necropsy on day
4 post partum.  No abnormal findings were noted for pups at first litter check or during the first 4 days post partum.
Sex ratios at first litter check and on day 4 post partum were unaffected by treatment with the test item.  Mean pup
weights on day 0 and day 1 post partum were unaffected by treatment with the test item. Mean pup weight development
during the first 4 days post partum lactation was unaffected by treatment with the test item.

Applicant's summary and conclusion

Conclusions:

The NOEL (No Observed Effect Level) for developmental toxicity was considered to be 100 mg/kg bw/day.