17-hydroxy-3-methoxyestra-2,5(10)-diene-17-carbonitrile

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Mar 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD guideline under GLP

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

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

17-hydroxy-3-methoxyestra-2,5(10)-diene-17-carbonitrile

EC Number:

241-083-5

EC Name:

17-hydroxy-3-methoxyestra-2,5(10)-diene-17-carbonitrile

Cas Number:

17006-17-6

Molecular formula:

C20H27NO2

IUPAC Name:

(3aS,3bR,9bS,11aS)-1-hydroxy-7-methoxy-11a-methyl-1H,2H,3H,3aH,3bH,4H,5H,6H,9H,9bH,10H,11H,11aH-cyclopenta[a]phenanthrene-1-carbonitrile

Details on test material:

- Name of test material (as cited in study report): Methoxyestradien-Cyanhydrin
- Analytical purity: 91.3%
- Lot/batch No.: 57046805

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.086 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 0.079 - 0.093

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.115 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.106 - 0.126

Any other information on results incl. tables

Table 1: Inhibition of biomass and the growth rate (%) of Scenedesmus subspicatus after 72 h exposure to ZK74834

		Inhibition in percent
Dilution of ZK74834	Concentration of ZK74834 (mg/L)	Biomass (integral)	Growth rate
0	0,0 (control)	0	0
1:64	0,0181 )	-5,77	-0,87
1:32	0,0371 )	4,81	1,62
1 :16	0,0731 )	39,03	15,63
1:8	0,1471 )	85,04	70,39
1:4	0,2941 )	77,64	60,19
1:2	0,5871 )	76,36	53,77

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ZK74834 had a concentration-depended inhibitory effect on the growth of Scenedesmus
subspicatus. The EbC50 (biomass) was 0.086 mg/L [95% confidence limits: 0.079 - 0.093], the ErC50 (growth rate) was 0.115 mg/L
[95% confidence limits: 0.106 - 0.126] on the basis of measured concentrations.
Consequently, ZK74834 is very toxic to the green algae Scenedesmus subspicatus.

Executive summary:

The purpose of the study was to determine the effects of Methoxyestradien-Cyanhydrin (ZK74834) on the growth of the green algae Scenedesmus subspicatus. ZK74834 is an intermediate of the synthesis of Gestonorone. The study was conducted in agreement with the test guidelines OECD-Guideline 201.

The test item was incubated in an aqueous solution including nutrients with an algae population of Scenedesmus subspicatus for a test duration of approximately 72 hours. The nutrient solution was made up according to the guidelines. For the preparation of the test solutions a suspension with a nominal loading of 100 mg/L ZK74834 was stirred for 24 hours. This suspension was filtered through a membrane filter (0.45 ~m). The resulting solution served as the saturated solution. It was further diluted for concentration levels of 1 :2, 1 :4, 1 :8, 1 :16, 1 :32 and 1 :64 with nutrient solution. The organic carbon concentration of the saturated solution was analysed with a DOC analyzer at the start and end of the incubation. The test item concentration was calculated on the basis of the molecular formula. The mean measured concentration of the saturated stock solution was determined with 1.17 mg/L. The further test concentrations were extrapolated from the result of the DOC-analysis and are shown in the table below.

As a parameter for the growth of the algae population, the cell density of the test and control solutions were measured via Chlorophyll-a-f1uorescence, excitation at 435 nm, emission 685 nm. Out of the f1uorescence values cell density values were calculated according to a calibration curve. The increase of biomass and the growth rate were calculated on the basis of the cell density. The calculated biomass and growth rate of each concentration were compared to those of the controls, and the inhibition was calculated.