Pregna-1,4,6-triene-3,20-dione, 17-(acetyloxy)-

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Nov 1998

Reliability:

1 (reliable without restriction)

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

GLP compliance:

yes

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

2.41

Temp.:

25 °C

pH:

>= 7

Details on results:

The log Pow value of the test compound is calculated from its log k', slope b and intercept a of the calibration line to be
Iog Pow = 2.41 (95 % confidence limits = 2.16 - 2.67)
This result differs from the result of a preliminary test log Pow = 3.17 (with warning for possible anomalous behaviour), which is obtained by calculation with the computer program CLOGP (version 3.4, Pomona College, Medical Chemistry Project, Claremont, USA). This method is based on the summation of molecular increments to the total log Pow of the substance.

Conclusions:

Iog Pow = 2.41 (95 % confidence limits = 2.16 - 2.67)

Executive summary:

The n-octanol/water partition coefficient of ZK 5560 was determined according to EU Testing Guideline A.8. (HPLC method based on OECD guideline no. 117)

log Pow = 2.41 (95 % confidence limits 2.16 -  2.67).

This method is based on the correlation of the reversed phase retention data of the test compound with those of reference compounds with known log P ow values.

Reference 2

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted calculation method.

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Guideline:

other: REACH guidance QSARs R6, May/July 2008

Principles of method if other than guideline:

Estimation Program Interface EPI-Suite version 4.11: KOWWIN for estimating the logarithmic octanol-water partition coefficient (log Kow).
The Estimation Programs Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).© 2000 - 2012 U.S. Environmental Protection Agency for EPI SuiteTM (Published online in November 2012).

GLP compliance:

no

Type of method:

other: QSAR

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

3.24

Validity of model:

1. Defined Endpoint:Octanol-water partition coefficient

2. Unambiguous algorithm:The molecule is separated into distinct atom/fragments using an Atom/Fragment Contribution method. Based on structure of the molecule, the following fragments were applied:

Fragment	Fragment Description
-CH3	[aliphatic carbon]
-CH2-	[aliphatic carbon]
-CH	[aliphatic carbon]
=CH- or =C<	[olefinc carbon]
-C (=O)-	[carbonyl, aliphatic attach]
-C (=O) O	[ester, aliphatic attach]
-tert Carbon	[3 or more carbon attach]
-C (=O)-	[carbonyl, olefinic attach]

The number of times of the fragments that occurs in the structure of the substance applied by the program is verified.

3. Applicability domain:With a molecular weight of 368.48 g/mole the substance is within the range of the training set (18.02 - 719.92 g/mole) as well as in the range of the validation set (27.03 - 991.15 g/mole).

4. Statistical characteristics:Correlation coefficient of the total training set r² = 0.982; Correlation coefficient of the total validation set r² = 0.943.

5. Mechanistic interpretation:The structural fragments used as descriptors reflect the lipophilic or hydrophobic properties of the substances, and so the octanol-water partition coefficient.

6. Adequacy of prediction:The result for the substance falls within the applicability domain described above and the estimation rules applied for the substance appear appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Conclusions:

The QSAR determination of the logarithmic octanol-water partition coefficient for the substance using the model KOWWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of 3.24 of the substance. The predicted value can be considered reliable yielding a useful result for further assessment.

Executive summary:

The logarithmic octanol-water partition coefficient (log Kow) for the substance was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v 4.11. The log Kow was estimated to be 3.24. The predicted value can be considered reliable yielding a useful result for further assessment.

Description of key information

The log Pow of the substance of 2.41 was determined in a study according to EU Method A.8.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.41

at the temperature of:

25 °C