Prasterone

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

other information

Study period:

Feb - May 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

Prasterone enantate (Androst-5-en-17-one, 3-hydroxy-, (3.beta.)) is the precursor and structural analogue of Prasterone (CAS 53-43-0). In vivo, it is releasing Prasterone into the body.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 490 (In Vitro Mammalian Cell Gene Mutation Tests Using the Thymidine Kinase Gene)

Version / remarks:

Method originally contained in TG 476, separated in TG 490 in 2016

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian cell gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

3 ß-Heptanoyloxy-5-androsten-17-one

IUPAC Name:

3 ß-Heptanoyloxy-5-androsten-17-one

Constituent 2

Reference substance name:

Prasterone enantate

IUPAC Name:

Prasterone enantate

Method

Target gene:

Thymidine kinase locus

Species / strain

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

The S9 liver homogenate, derived from male Sprague-Dawley rats pre-treated with
Aroclor 1254, was obtained from MP Biomedicals GmbH, Eschwege, Germany (S9 batch no. 4949H; protein content 38.1 mg/mL; EROD activity: 5256.63 pmoles 7-hydroxyresorufin formed per minute per mg protein). The S9 mix was prepared with 200 mmol/Lglucose-6-phosphate, 32 mmol/L NADP and S9 at a ratio of 1: 1 :2.
Immediately before treatment an appropriate quantity of S9 was thawed and mixed with the cofactors and added to the test cultures at a ratio of 1 :20 representing final concentrations of 2.5 mmol/L glucose-6-phosphate, 0.4 mmol/L NADP and 2.5% S9.

Test concentrations with justification for top dose:

20, 40, 60, 80, 100 µg/ ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: solubility

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

3-methylcholanthrene

4-nitroquinoline-N-oxide

Results and discussion

Test results

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at ≥ 60 µg/mL

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Evaluation of the data does not indicate that prasterone enantate is a mutagen in the mouse lymphoma assay, when tested up to dear cytotoxic and precipitating dose levels in the absence and presence of metabolic activation.

Executive summary:

In the reported study prasterone enantate did not lead to an increase in the number of mutant colonies that exceeded the threshold of twice the mutant colony counts of the corresponding solvent controls, when tested up to the recommended dose levels in the absence or presence of metabolic activation. No relevant shift in the ratio of small and large mutant colonies was determined at any test concentration.
Cytotoxic effects of prasterone enantate could be observed in the nonactivated treatments starting at test concentrations of 60 µg/mL (pulse treatment) and 25 µg/mL (continuous treatment). In the activated treatments only weak cytotoxic effects were induced at the highest test concentration of 120 µg/mL.
Visible precipitates of the test substance in the cell culture medium occurred starting at 80 µg/mL.
The negative and solvent controls (medium and 1 % DMSO) showed spontaneous mutant frequencies in the expected range. The positive controls NQO (0.025 and 0.1 µg/mL) and 3-MC (2.0 µg/mL) induced significant increases in the mutant frequency indicating the sensitivity of the test system.