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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
February 2017
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship (HA-QSAR) based on a holistic approach for predicting physicochemical and ecotoxicological endpoints: Octanol-water partition coefficient

1. SOFTWARE
iSafeRat® toolbox – in Silico Algorithms For Environmental Risk And Toxicity version 2.2

2. MODEL (incl. version number)
iSafeRat® holistic HA-QSAR v1.6

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES codes of the constituents (see attached QPRF of each constituent)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
yes
Remarks:
QSAR model
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
yes
Remarks:
QSAR model
Principles of method if other than guideline:
A Quantitative Structure-Property Relationship (QSPR) model was used to calculate the n-octanol/water partition coefficients of the consituents of the test item (a Natural Complex Substance). This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 107, "Partition Coeficient (n-octanol/water): Shake Flask Method" and No. 123 "Partition Coeficient (n-octanol/water): Slow Stirring Method”. The criterion predicted was the log KOW (also known as log POW).

The determination was performed using a fragment based approach in which the molecule is divided into large and small fragments and each fragment is related to a specific log KOW contribution which may be positive or negative. The final log KOW is determined by simple addition of the fragments. The predicted log KOW values have been validated against high quality experimental studies generally using the shake-flask method but slow-stir values have been used when available. The results are considered to be as accurate as those from a good quality OECD 107 or 123 study.
GLP compliance:
no
Type of method:
other: QSAR
Key result
Type:
log Pow
Partition coefficient:
4.6
Temp.:
25 °C
Remarks on result:
other: Constituent 1
Key result
Type:
log Pow
Partition coefficient:
4.7
Temp.:
25 °C
Remarks on result:
other: Constituent 2
Key result
Type:
log Pow
Partition coefficient:
4.6
Temp.:
25 °C
Remarks on result:
other: Constituent 3
Key result
Type:
log Pow
Partition coefficient:
2.6
Temp.:
25 °C
Remarks on result:
other: Constituent 4
Key result
Type:
log Pow
Partition coefficient:
4.4
Temp.:
25 °C
Remarks on result:
other: Constituent 5
Key result
Type:
log Pow
Partition coefficient:
2.5
Temp.:
25 °C
Remarks on result:
other: Constituent 6
Key result
Type:
log Pow
Partition coefficient:
4.2
Temp.:
25 °C
Remarks on result:
other: Constituent 7
Key result
Type:
log Pow
Partition coefficient:
4.5
Temp.:
25 °C
Remarks on result:
other: Constituent 8
Key result
Type:
log Pow
Partition coefficient:
3.1
Temp.:
25 °C
Remarks on result:
other: Constituent 9
Key result
Type:
log Pow
Partition coefficient:
4.8
Temp.:
25 °C
Remarks on result:
other: Constituent 10
Key result
Type:
log Pow
Partition coefficient:
4.3
Temp.:
25 °C
Remarks on result:
other: Constituent 11

The partition coefficient of the test item was estimated using the recommended QSAR modeliSafeRat®, based on Regression based-Fragment Approach’(RFA) method. The substance is within the applicability domain (MW, descriptors).

The calculated range is between: 2.5 -4.8 at 25°C

The logKOWare calculated as follows:

 

log KOWat 25°C

references

Constituent 1

4.6

See QPRF

Constituent 2

4.7

See QPRF

Constituent 3

4.6

See QPRF

Constituent 4

2.6

See QPRF

Constituent 5

4.4

See QPRF

Constituent 6

2.5

See QPRF

Constituent 7

4.2

See QPRF

Constituent 8

4.5

See QPRF

Constituent 9

3.1

See QPRF

Constituent 10

4.8

See QPRF

Constituent 11

4.3

See QPRF

Conclusions:
The log KoW of 11 major components of the substance (more than 90% of the composition) are predicted to be between 2.5-4.8 at 25°C.
Executive summary:

A Quantitative Structure-Property Relationship (QSPR) model was used to calculate the noctanol/water partition coefficients of the consituents of the test item, a Natural Complex Substance. This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 107, "Partition Coeficient (n-octanol/water): Shake Flask Method" and No. 123 "Partition Coeficient (n-octanol/water): Slow Stirring Method”.

The constituents are within the applicability domain (MW, descriptors).

The calculated log Kow of 11 major constituents of the test item (more than 90% of the composition) are between 2.5 and 4.8 at 25°C.

The log KOW was predicted as follows:

 

log KOWat 25°C

Constituent 1

4.6

Constituent 2

4.7

Constituent 3

4.6

Constituent 4

2.6

Constituent 5

4.4

Constituent 6

2.5

Constituent 7

4.2

Constituent 8

4.5

Constituent 9

3.1

Constituent 10

4.8

Constituent 11

4.3

Description of key information

The partition coefficient of Elemicin was estimated using the QSAR model iSafeRat® holistic HA-QSAR v1.6, based on Regression based-Fragment Approach’(RFA) method. The substance is within the applicability domain.

The calculated log Kow is 2.6 at 25°C.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.6
at the temperature of:
25 °C

Additional information