Registration Dossier
Registration Dossier
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EC number: 208-289-7 | CAS number: 520-27-4
Dissociation constant
Administrative data
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- comparable to guideline study with acceptable restrictions
Data source
Reference
- Reference Type:
- publication
- Title:
- Unnamed
- Year:
- 2 008
- Report date:
- 2008
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The ionisation curve was calculated from the effective mobility of the test item against pH, obtained by capillary electrophoresis. No further details provided on the method.
- GLP compliance:
- not specified
Test material
- Reference substance name:
- Diosmin
- EC Number:
- 208-289-7
- EC Name:
- Diosmin
- Cas Number:
- 520-27-4
- Molecular formula:
- C28H32O15
- IUPAC Name:
- diosmin
- Test material form:
- not specified
Constituent 1
Results and discussion
Dissociation constantopen allclose all
- No.:
- #1
- pKa:
- 10.1
- Remarks on result:
- other: temperature not specified.
- No.:
- #2
- pKa:
- 10.1
- Remarks on result:
- other: temperature not specified.
Any other information on results incl. tables
Table 1. Ionisation constants and absolute mobilities of mono and double charged ions experimentally determined by capillary electrophoresis (Sigmoidal adjustment of CE mobilities against pH, GraphPad Prism 5) and estimated (Marvin Sketch, Chemaxon).
|
Diosmin |
|
Experimental |
Estimated |
|
pKa1 |
10.1 ± 0.2 |
9.39 |
pKa2 |
10.1 ± 0.2 |
10.07 |
Ma2- |
-6.5E-5 |
|
pKa3 - pKa8 |
> 11.50 |
≥ 12.36 |
Applicant's summary and conclusion
- Conclusions:
- The pKa values obtained for the test item were pKa1 = 10.1 ± 0.2 and pKa2 = 10.1± 0.2.
- Executive summary:
The dissociation constant of the test item was calculated from its ionisation curve, which was obtained by non-linear regression fitting of a sigmoidal curve to the effective mobilities of the test compound against pH, determined by capillary electrophoresis. Eight pKa values were expected, considering the number of ionisable OH groups in the molecule (two phenolic OH and six alcoholic OH groups), as estimated using MarvinSketch program. However, since dissociation of the alcoholic OHs occurs only in strongly basic conditions, which are outside of the experimental pH range of this methodology, it was not possible to determine them. The pKa values obtained were pKa1 = 10.1 ± 0.2 and pKa2 = 10.1± 0.2.
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