L-Tyrosine, N-acetyl-3,5-diamino-O-(4-methoxyphenyl)-, ethyl ester

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

ethyl (2S)-3-[3,5-diamino-4-(4-methoxyphenoxy)phenyl]-2-acetamidopropanoate

Cas Number:

440667-78-7

Molecular formula:

C20H25N3O5

IUPAC Name:

ethyl (2S)-3-[3,5-diamino-4-(4-methoxyphenoxy)phenyl]-2-acetamidopropanoate

Test material form:

solid: particulate/powder

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

Test conditions

Test temperature:

22.0-22.5 °C

pH:

7.3-7.8

Nominal and measured concentrations:

1 / 3.2 / 10 / 32 / 100 mg/L nominal concentration

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

77.98 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

53.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

< 1.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 1.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

One valid experiment was performed.
The study was performed using 5 concentrations ranging from 1 to 100 mg/L (nominal). Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.

At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC.
The measured concentrations lay between 92 % and 97 % of the nominal concentrations at the beginning of the test and between 82 % and 136 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations (see OECD 201 (§ 39)).

The 72h-EC50 values of potassium dichromate (K2Cr2O7, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.65 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

The pH of the blank control should not fluctuate by more than 1.5 units. The change was 0.3 units in the blank control.

All validity criteria were met.
No observations were made which might cause doubts concerning the validity of the study outcome. The result of the test can be considered valid

Executive summary:

Findings and Results:

One valid experiment was performed.

The study was performed using 5 concentrations ranging from 1 to 100 mg/L (nominal). Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield[1] were determined from the cell number at the respective observation times.

 

At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC.

The measured concentrations lay between 92 % and 97 % of the nominal concentrations at the beginning of the test and between 82 % and 136 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations (see OECD 201 (§ 39)).

The 72h-EC₅₀ values of potassium dichromate (K₂Cr₂O₇, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.65 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

 

The following results for the test item L-Tyrosine, N-acetyl-3,5-diamino-O-(4-methoxyphenyl)-, ethyl ester were determined:

Table 3                Results of the test item

Endpoint	NOEC	LOEC	EC10	EC50
Growth Rate	< 1.10 mg/L	≤ 1.10 mg/L	53.60 mg/L	n. d.
Yield	< 1.10 mg/L	≤ 1.10 mg/L	1.32 mg/L	77.98 mg/L

1. d. = not determinable due to mathematical reasons or inappropriate data

EC₅₀ and EC₁₀ were determined by regression analysis and are read from the graph toxicity vs. concentration. In contrast, the NOEC was determined by comparing the respective treatment with the blank control using a hypothesis test.

 Because of no statistical significant difference between the blank control and the lowest tested concentration was observed, the NOEC was determined as lower than the lowest concentration.

 

[1] Yield (according to OECD Guideline 201) is defined as the biomass at the end of the exposure period minus the biomass at the start of the exposure period. Calculation see under 8.2 Growth and growth inhibition are quantified from measurements of the algal biomass as a function of time. Algal biomass is defined as the dry weight per volume, e.g. mg algae/L test solution. However, dry weight is difficult to measure and therefore surrogate parameters are used. Of these surrogates, cell counts are most often used.