Tetrahydrothiopyran-3-carboxaldehyde

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes

Limit test:

no

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of' test substance: Tetrahydrothiopyran-3-aldehyd
- Test substance number: 89/713
- Charge No.: out of barrel 72, from November 1, 1988
- Degree of purity: about 93%
- State, color: liquid, colorless
- Storage condition: keep cool

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr. Karl Thomae GmbH, Biberach/Riss. FRG
- Strain/quality: Wistar rats Chbb =THOM (SPF)
- Age at study initiation: 42 days
- Mean weight at study initiation: 186 (177 - 195) g for males, 154 (145 - 162) g for females
- Fasting period before study: none
- Housing: singly in type DK III stainless steel wire mesh cages supplied by BECKER & Co., Castrop-Rauxel, FRG, floor area about 800 cm²
- Diet: ground Kliba maintenance diet rat/mouse/hamster, 343 meal, supplied by Klingentalmuehle AG, CH-4303 Kaiseraugst. Switzerland ad libitum
- Water: drinking water ad libitum
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

The rats were unambiguously identified by ear tattoos. The unit digit of the animal number was tattooed into the outside of the left ear and the ten digit into the inside of the left ear.

Food analyses
The food used in the study was assayed for chemical and microbiological contaminants.

Drinking water analyses
The drinking water is regularly assayed for chemical contaminants by the municipal authorities of Frankenthal and the Technical Services of BASF AG as well as for the presence of germs by a contract laboratory.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The test substance was administered as a solution in olive oil. To prepare the solution Tetrahydrothiopyran-3-aldehyd was weighed depending on the dose group. then olive oil DAB 9 was filled up to the mark and was subsequently dissolved by magnetic stirrer. The test substance preparations were made prior to each administration.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

At the start of the study samples were sent to the analytical laboratory for determination of the correctness of the concentration of the test substance preparations. The characterisation of the test substance was performed by elementary analysis and other physico-chemical methods. The analysis of the test substance in the vehicle was determined by Capillary gas chromatography.

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily (except Saturdays and Sundays, 21 times)

Doses / concentrations

Remarks:

Doses / Concentrations:
15 mg/kg, 150 mg/kg, 1,000 mg/kg body weight
Basis:
actual ingested

No. of animals per sex per dose:

5 males and 5 females per dosing group
5 males and 5 females in the control group

Control animals:

yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:

INTRODUCTION AND DOSE SELECTION
The aim of the study was to determine the toxicological profile and the no adverse effect level of Tetrahydrothiopyran-3-aldehyd including the target organs. After 4-week administration by gavage (21 x p.o.). The LD50 value (rat, oral) was about 5,000 mg/kg body weight for the males and about 3,120 mg/kg body weight for the females (ZST-No.: 84/242). The 2-week test administration by gavage (11 x p.o., Project No.: 11SO713/89095) to male and female Wistar rats in doses of 500 and 1.000 mg/kg body weight led to no impairment of the general state of health. From the 6th application onward salivation was seen in the highest dose group immediately after dosing (not detectable 10 minutes after that). Body weight gain in males was decreased in the highest dose group (about 8% less than the control group). Food consumption in both sexes was decreased (males about 13%. females about 8%). Hematological and clinicochemical revealed no substance-induced changes. No changes were observed at necropsy including absolute and relative organ weights.
Therefore the following doses were chosen for the 4-week administration period:
15 mg/kg body weight: as the expected "no adverse effect level”
150 mg/kg body weight: as the intermediate dose level
1.000 mg/kg body weight: as the high dose expected to have toxic effects.

ANALYSES
The analyses were carried out in the analytical laboratories of BASF AG.

Analyses of the test substance
The analyses regarding the characterization and the homogeneity of the test substance were carried out prior to the start of the study. In the course of the study period, a white precipitate was noticed in the bottles from which the substance was taken. The same phenomenon was seen in other bottles from which substance had been taken previously. For the preparation of the concentrations the liquid upper phase was taken. In order to control the stability and to determine the correct concentration of test substance a bottle (with precipitate and upper phase) was sent to the analytical laboratory in the course of the study. The stability of the test substance was checked anew after the end of all studies with the test substance.

Preparation and analyses of the doses
The test substance was administered as a solution in olive oil. To prepare the solution Tetrahydrothiopyran-3-aldehyd was weighed depending on the dose group. then olive oil DAB 9 was filled up to the mark and was subsequently dissolved by magnetic stirrer. The test substance preparations were made prior to each administration. Before the beginning of the study, the stability of the test substance in the vehicle over a period of 4 hours was verified analytically. At the start of the study samples were sent to the analytical laboratory for determination of the correctness of the concentration of the test substance preparations.

Methods
The characterisation of the test substance was performed by elementary analysis and other physico-chemical methods. The analysis of the test substance in the vehicle was determined by Capillary gaschromatography.

Food analyses
The food used in the study was assayed for chemical and microbiological contaminants.

Drinking water analyses
The drinking water is regularly assayed for chemical contaminants by the municipal authorities of Frankenthal and the Technical Services of BASF AG as well as for the presence of germs by a contract laboratory.

EXPERIMENTAL PROCEDLIRE
The 34 days old animals were delivered on February 18, 1991 and subjected on the same day to a 8-day acclimatization period during which the animals received ground food and drinking water ad libitum. Before the start of the administration period the animals, separated by sex, were distributed according to weight among the individual test groups. The list of randomization instructions was compiled with a computer (laboratory data processing, Department of Toxicology, BASF AG).
At the start of administration of the test substance the rats were 42 days old and had a mean weight of
-186 (177 - 195) g for the males
-154 (145 - 162> g for the females.
At the beginning of the administration period the animals of test groups 1 - 3 daily (except Saturdays and Sundays, 21 times) received the corresponding test substance preparations of Tetrahydrothiopyran-3-aldehyd by gavage in varying amounts depending on the last body weight determination. The animals of the control group received the vehicle (olive oil) alone by gavage. The last application has been carried out one day before sacrificing. All animals were sacrificed following a fasting period (withdrawal of food) for about 16 – 20 hours.

CLINICAL EXAMINATIONS
Food consumption
The food consumption over a period of 7 days was determined weekly and calculated as mean food consumption in grams per animal and day.

Body weight data
The body weight was determined before the start of the administration period in order to randomize the animals. During the conduct of the study, the body weight was determined on day 0 (start of the administration period) and thereafter in weekly intervals.

Intake of test substance and administration volume
The amounts of test substance preparation to be administered to each animal were calculated once a week on the day of body weight determination. The test substance was administered to the males and females on the basis of the doses 15, 150 and 1,000 mg/kg body weight and the administration volume (5 ml/kg body weight). The list of the individual administration volumes was generated on the computer systems of BASF AG.

Clinical observations
A check was made twice Mondays to Fridays and once a day on Saturdays, Sundays and public holidays for general observations. Once a week an additional exact clinical examination was carried out. The animals were checked for the appearance of clinical observations before and after each administration. All observations were recorded.

Mortality
A check was made twice Mondays to Fridays and once a day on Saturdays, Sundays and public holidays for any dead or moribund animals.

CLINICAL CHEMISTRY AND HEMATOLOGY
Blood was taken from the retroorbital venous plexus in the morning from non-fasted, not anesthetized animals. The blood samplings and the subsequent analysis of the blood and serum samples were carried out in a randomized sequence. The list of randomization instructions was compiled with a computer using a random number generator.

The assays of blood and serum parameters were performed under internal laboratory quality control conditions with commercial reference controls to assure reliable test results. The results of the clinicochemical and hematological examinations are expressed in units of the International System (SI). The following examinations were carried out in 5 animals per test group and sex:

Hematological examinations
The following parameters were determined in blood with EDTA-KG as anticoagulant using a particle counter (S Plus model by Coulter, Krefeld. FRG):
- leukocytes
- erythrocytes
- hemoglobin
- hematocrit
- mean corpuscular volume
- mean corpuscular hemoglobin
- mean corpuscular hemoglobin concentration
- platelets
The data obtained were transferred to a computer (VAX 11/780; supplied by DEC. Munich, FRG).
The differential blood count was evaluated visually. The data were transferred to the computer.

Clotting analyses
The clotting analyses were carried out using a ball coagulometer (KC 10 model, by Amelung, Lemgo. FRG) and the results transferred off-line to the computer.
The following parameter was determined:
- thromboplastin time (Hepato Quick's test)

Clinicochemical examinations
An automatic analyzer (Hitachi 737; by Boehringer, Mannheim, FRG) was used to examine the clinicochemical parameters. The values obtained were transferred to a computer (VAX 11/780; by DEC, Munich, FRG).

The following parameters were determined:
1. Enzymes
- alanine aminotransferase
- aspartate aminotransferase
- alkaline phosphatase
- serum-g-glutamyltransferase

2. Blood chemistry
- sodium
- potassium
- chloride
- inorganic phosphate
- calcium
- urea
- creatinine
- glucose
- total bilirubin
- total protein
- albumin
- globulins
- triglycerides
- cholesterol
- magnesium

Statistics:

The data were evaluated statistically an the computer systems of the Department of Toxicology of BASF AG.

Clinical examinations
Mean and standard deviation were calculated for the variables food consumption and body weight for each test group and tabulated together with the individual values for food consumption and body weight. For body weight a non-parametric one-way analysis was performed using the KRUSKAL-WALLIS test . If the resulting p-value is equal or less than 0.05, a pairwise comparison of each dose group with the control group was carried out. This comparison was performed via the MANNWHITNEY U-test for hypothesis of equal medians. If the results of this test are significant, labels (* for p < 0.05, ** for < 0.02, ** for < 0.002) were printed together with the group means in the tables. Both tests were performed two-sided.

Clinical chemistry and hematology
Mean and standard deviation were calculated for each test group and tabulated together with the individual values. Except for the differential blood count, a statistic one-way analysis of variance is done via the KRUSKALWALLIS-h-test. If the resulting p-value is equal or less than 0.05 a pairwise comparison of each dose group with the control group was carried out. This comparison is done using the MANN-WHITNEY-U-test for the hypotheses of equal medians. If the results of this test are significant, p-markers (* for p < 0.05, ** for < 0.02, ** for < 0.002) were printed together with the group mean in the tables.

Results and discussion

Results of examinations

Details on results:

RESULTS AND ASSESSHENT OF FINDINGS
ANALYSES
Analyses of the test substance
The analyses regarding the characterization of the test substance were carried out prior to the start of the study. The degree of purity of the test substance was about 93 %. On visual inspection the test substance is a homogeneous colorless, slight movable liquid. A comparison of the first analytical data indicated, that the content of tetrahydrothiopyran-3-aldehyd in the test substance during the application period and after the end of the toxicological examinations was about 4% and 3% lower, respectively.

Analyses of the doses
The stability of the test substance in the vehicle over a period of 4 hours and the correctness of the concentrations were verified analytically.

Food analyses
In view of the aim and duration of the study the contaminants occurring in commercial food might not influence the results.

Drinking water analyses
In view of the aim and duration of the study there are no special requirements exceeding the specification of drinking water.

CLINICAL EXAMINATIONS
Food consumption
The animals showed no difference, when compared with the control group, with the exception of both sexes of the highest test group (1,000 mg/kg body weight) which showed decreased food consumption in the 1st week only.

Body weight data
Throughout the course of the study, body weight of the male rats of the highest test group was decreased (in the 1st week significantly only). All other animals of the test groups showed no difference, when compared with the control group.

Clinical observations
From the 6th application onward (7 days after start of the study) salivation was seen in both sexes of the 1.000 mg/kg body weight group immediately after dosing (not detectable 10 minutes after that). After the 2nd and 3rd application-free weekends (Saturday and Sunday) no salivation was observed after substance administration an Monday. An increased water consumption was noted from the 3rd week up to the end af the study in the highest dosage group (1,000 mg/kg body weight). The visually noted increased water consumption was confirmed (by weighing the drinking water bottles). Details can be found with the raw data.

Mortality
No animal died during the course af the study.

CLINICAL CHEMISTRY AND HEMATOLOGY
Hematological examinations
No substance-induced changes were noted

Clotting analyses
No substance-induced changes were detected

Enzymes
At the end of the administration period statistically significantly increased alkaline phosphatase activities were found in the serum of the female animals of test group 3 (1.000 mg/kg body weight). This finding is assessed as being treatment-related and might be assigned to a slight functional impairment of the liver. The other enzyme examinations revealed no changes which are due to the test substance administered.

Blood chemistry
In the serum of the female animals of the highest dose group (1,000 mg/kg body weight) statistically significantly decreased chloride concentrations were detected at the end of the study. Although this isolated finding is difficult to assess in its etiology, the decreased chloride level is regarded to be substance-induced. In the remaining clinicochemical parameters no substance-related changes were observed.

Other deviations
There is a further statistically significant inter-group difference in the results of the white blood cell count. This isolated deviation is inconsistent and is lacking dosage-relationship. Accordingly, this change is considered to be of no toxicological significance.

DISCUSSION AND CONCLUSION
In the clinical examinations the following substance-induced changes were observed:
Test group 3 (1.000 mg/kg body weight)
- Decrease of food consumption in both sexes only in the first week
- Decrease of body weight in males during the course of the study (significantly decreased only in the first week)
- Increase of water consumption in both sexes for the last two weeks
- Salivation after application, not detectable 10 minutes after that

Test groups 1 and 2 (15 and 150 mg/kg body weight)
No substance-induced changes were detected.

In the clinicochemical and hematological examinations the following substance-induced changes were observed:
Test group 3 (1.000 mg/kg body weight)
- Increase in alkaline phosphatase in the female animals
- Decrease in chloride in the female animals

Test groups 1 and 2 (15 and 150 mg/kg body weight)
No substance-induced changes were detected

In the macroscopic and the histopathological examinations following treatment-related findings were detected:
Test group 3 (1.000 mg/kg body weight)
- Statistically significantly increased absolute and relative liver weights in the female animals
- Diffuse or focal thickening of the forestomach's wall in 4 male and 5 female animals (macroscopically)hyperkeratosis and/or parakeratosis and epithelial hyperplasia in the forestomach of all males and females
- Slight centro-lobular single cell necrosis of the liver in both sexes

Test group 2 (150 mg/kg body weight)
- Minimal hyperkeratosis and epithelial hyperplasia in the forestomach in both sexes

Test group 1 (15 mg/kg body weight)
- No substance-induced changes were detected

Oral treatment with Tetrahydrothiopyran-3-aldehyd resulted in toxicologically significant changes at dose levels of 1,000 and 150 mg/kg body weight. No treatment-related effects were observed in animals treated with 15 mg/kg body weight.

Effect levels

Dose descriptor:

NOEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: overall effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

SUMMARY

Tetrahydrothiopyran-3-aldehyd was administered to 30 Wistar rats (15 males and 15 females) by gavage for 4 weeks (21 times). A control group (5 per sex) was dosed with vehicle alone (olive oil). The doses were 15 mg/kg body weight (test group 1), 150 mg/kg body weight (test group 2) and 1,000 mg/kg body weight (test group 3). Food consumption and body weight were determined weekly. The state of health was checked each day and once a week the rats were inspected and palpated. The animals were checked for the appearance of clinical observations before and after each administration. At the end of the study a clinicochemical and hematological examination was carried out. All animals were assessed by gross pathology, followed by a histopathological examination.

 

Results:

It can be stated that the administration of Tetrahydrothiopyran-3-aldehyd to Wistar rats by gavage for 4 weeks (21 times) caused following findings:

1.000 mg/kg body weight:

- Decreased food consumption only in the first week

- Decreased body weight gain in males during the course of the study (significantly decreased only the first week)

- Increased water consumption for the last two weeks

- Salivation after application, not detectable 10 minutes after that

- Increased alkaline phosphatase in the female animals

- Decreased chloride in the female animals

- Statistically significantly increased absolute and relative liver weights in the female animals

- Diffuse or focal thickening of the forestomach*s wall in both sexes (macroscopically), hyperkeratosis and/or parakeratosis and epithelial hyperplasia in the forestomach of all males and females

- Slight centrolobular single cell necrosis of the liver in both sexes

 

150 mg/kg body weight:

- Minimal hyperkeratosis and epithelial hyperplasia in the forestomach in both sexes

 

15 mg/kg body weight:

- No substance-induced changes were detected

 

The observed effects in the forestomach of the rats in the 150 mg/kg body weight group are no doubt treatment-related due to the irritative property of the substance but no signs of systemic toxicity have been observed. Based on the results obtained during this oral toxicity study the ‹no adverse effect level of Tetrahydrothiopyran-3-aldehyd is in the range lower than 1.000 mg/kg body weight and greater than 150 mg/kg body weight.