Escin

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Version / remarks:

17 July 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Version / remarks:

January 1998

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Escin

EC Number:

229-880-6

EC Name:

Escin

Cas Number:

6805-41-0

Molecular formula:

C110H172O48

IUPAC Name:

(2S,3S,4S,5R,6R)-6-{[(3S,4S,4aR,6aR,6bS,8R,8aR,9R,10R,12aS,14aR,14bR)-9-(acetyloxy)-8-hydroxy-4,8a-bis(hydroxymethyl)-4,6a,6b,11,11,14b-hexamethyl-10-[(2-methylbutanoyl)oxy]-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-icosahydropicen-3-yl]oxy}-4-hydroxy-3,5-bis({[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy})oxane-2-carboxylic acid; (2S,3S,4S,5R,6R)-6-{[(3S,4S,4aR,6aR,6bS,8R,8aR,9R,10R,12aS,14aR,14bR)-9-(acetyloxy)-8-hydroxy-4,8a-bis(hydroxymethyl)-4,6a,6b,11,11,14b-hexamethyl-10-{[(2E)-2-methylbut-2-enoyl]oxy}-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-icosahydropicen-3-yl]oxy}-4-hydroxy-3,5-bis({[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy})oxane-2-carboxylic acid

Test material form:

solid: bulk

Specific details on test material used for the study:

Horse-Chestnut dry hydroalcoholic extract 16-22% contained saponin as escin according to Ph. Fr. X Ed.

Study design

Oxygen conditions:

not specified

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Species: Activated sludge, microorganisms from domestic waste water treatment plant.

Preparation of Activated slugfe inoculum: The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in isotonic saline solution with shaking and again centrifuged. This procedure was repeated twice.An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to dry weight determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 5g dry material per litre was mixed with reconstituted water and then aerated under test condictions (for 6 days) until use. The pH of the activated sludge inoculum after preparation was: 7.34, just before use: 6.8. A pH adjustment of activated sludge inoculum was not performed.

Pre-conditioning of activated sludge inoculum: Pre-conditioning consisted of aerating (2L/minute) activate sludge (in mineral medium, reconstituted water) for 6 days at the test temperature. During the aeration the cell count of inoculum was checked as followS: the viability of the cultured sludge was determined by plating0.1 mL of the different, usually 10-2, 10-3, 10-4 and 10-5 dilutions of cultures on nutrient agar plates. The viable cell number of the cultures was determined by these plating experiments by manual colony counting. The approximately cell count of aerated inoculum fell in the range of 108 cells/L; thereforee on the day of the test this inoculum was diluted 1000x with reconstituted water to reach the necessary ca. 105 cells/L cell concentration. After preparation the sludge was filtered through cotton wool. Pre-conditioning improves the precision of the method. The inoculum was not pre-adapted to the test chemical.

Duration of test (contact time):

28 d

Details on study design:

Enviromental ondiction:
The test was carried out in a controlled enviroment room (during the formulation and oxygen measuring) at a temperature of 22+- 2°C according to the giudeline. The test flasks were incubated an a controlled environment room at 22+-2°C, in the dark. temperature was measured continously using min(max thermometer and noticed every day. During pre-conditioning of activated sludge inoculum the temperature was 20.1 - 21.7 °C; during the preparation, aeration and incubation of the reconstituted water preparation of the test bottles (units) the temperature was 20.3 - 21.3 °C. During the incubation (28 days) of the test units the temperature range was the following: 20.1 - 21.4°C. The oxygen concentration of the test water was in the range of 8-9 mg/L. It was measured at the start of the test and found to be 8.73 mf/L. The pH was checked prior study start and found to be 7.24. A pH adjustment was considered as not necessary. The test conditions were measured with suitable instruments and documented in the raw data.

Results and discussion

Preliminary study:

cfr attchment

Test performance:

cfr attchment

% Degradation

Key result

Parameter:

% degradation (test mat. analysis)

Value:

>= 31 - <= 38.8

Sampling time:

28 d

Details on results:

cfr attachment

BOD5 / COD results

BOD5 / COD

Key result

Parameter:

COD

Value:

60 mg O2/g test mat.

Results with reference substance:

CFR attachment

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item was considered to be not ready biodegradable. According to the test guidelines the pass level for biodegradability is 60% of COD.
In This study total oxydised nitrogen (nitrate and nitrite) concentration determination was not performed after each oxygen measurement.
According to the test guidelines the test item can be assumed as not inhibitory on the activated sludge microorganisms because the degradation in the toxicity control group was higher than 25% within 14 days.
The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum